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SERV1828January 2007

TECHNICAL PRESENTATION

777F (JRP)OFF-HIGHWAY TRUCK

INTRODUCTION

Service Training Meeting Guide(STMG)

GLOBAL SERVICE LEARNING

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777F (JRP) OFF-HIGHWAY TRUCKINTRODUCTION

MEETING GUIDE 828 VISUALS AND SCRIPT

AUDIENCE

Level II - Service personnel who understand the principles of machine system operation,diagnostic equipment, and procedures for testing and adjusting.

CONTENT

This presentation provides basic maintenance information and describes the systems operationof the monitoring system, engine, power train, steering, hoist and brakes for the 777F Off-highway Truck. The Automatic Retarder Control (ARC) and the Traction Control System(TCS) are also discussed. This presentation may also be used for self-paced and self-directedlearning.

OBJECTIVES

After learning the information in this meeting guide, the serviceman will be able to:1. locate and identify the major components in the engine, power train, steering, and

brakes;

2. explain the operation of the major components in the systems; and

3. trace the flow of oil through the systems.

REFERENCES

777F (JRP) Operation and Maintenance Manual SEBU7790777F (JRP) Parts Manual SEBP4305

PREREQUISITES

"Fundamentals of Engines Self Study Course" TEMV3001"Fundamentals of Mobile Hydraulics Self Study Course" TEMV3002"Fundamentals of Power Trains Self Study Course" TEMV3003"Fundamentals of Electrical Systems Self Study Course" TEMV3004

Estimated Time: 24 HoursVisuals: 224Handouts: 30Form: SERV1828Date: 01/07

© 2007 Caterpillar Inc.

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SUPPLEMENTAL MATERIAL

Reference Manuals

Fluid Power Graphic Symbols User's Guide SENR3981Cold Weather Recommendations for Caterpillar Machines SEBU5898Caterpillar Machine Fluids Recommendations SEBU6250

Salesgrams and Product Bulletins

Training Bulletin "Caterpillar Transmission/Drive Train Oil" TEJB1002Product Bulletin "Reporting Particle Count By ISO Code" PEJT5025Salesgram "Caterpillar Extended Life Coolant" TEKQ0072Product Data Sheet "Caterpillar Extended Life Coolant" PEHP4036

Technical Instruction Modules on Legacy DVDs SERV1000-01(These materials can not be ordered separately.)

Automatic Retarder Control System SEGV2593Automatic Electronic Traction Aid SEGV2585769C - 793B Off-highway Trucks--Suspension System SEGV2599Truck Payload Measurement System SEGV2579

Service Training Meeting Guides

STMG 721 "777D Update (AGC) Off-highway Truck" (CD ROM) SERV1721

Video Tapes

Suspension Cylinder Charging TEVN2155TPMS Management/Technical Information AEVN2211TPMS Operating Tips AEVN2212Introduction to the Automatic Electronic Traction Aid SEVN9187Mining Trucks--Cleanliness and Component Life SEVN4142Oil Sampling--The Right Way PEVN4638

Booklets

Know Your Cooling System SEBD0518Diesel Fuels and Your Engine SEBD0717Oil and Your Engine SEBD0640Understanding The S•O•S Report TEJB1015

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SUPPLEMENTAL MATERIAL (Continued)

Special Instructions

Accessing Flash Software for Machines REHS0494Caterpillar Electronic Controls Service Code Information Description List REHS0126Using the 7X1700 Communication Adapter Group SEHS9264Using the 261-3363 Wireless Communications Adapter NEHS0926Use of CE Connector Tools SEHS9065Servicing DT Connectors SEHS9615Parts Listing Of The Deutsch Connectors And Components REHS0148Use of 6V3000 Sure-Seal Repair Kit SMHS7531Use of 8T5200 Signal Generator/Counter Group SEHS8579Suspension Cylinder Servicing SEHS9411777F Assembly Procedure REHS2594

Brochures

Caterpillar Electronic Technician NEHP5614Caterpillar DataView NEHP5622Diesel Engine Oil (CH4) Product Data Sheet PEHP8038How to Take a Good Oil Sample PEHP6001S•O•S Coolant Analysis PEHP5033Air Filter Service Indicator PEHP9013Cat Oil Cooled, Multiple Disc Brakes AECQ5980Caterpillar Automatic Retarder Control AEDK0075Caterpillar "D" Series Truck Cabs AEDK0706Caterpillar Truck Frames AEDK0707Mining Truck Bodies: Selecting The Right Body System For Your Job AEDK0083Caterpillar Truck Production Management System: Answering yourquestions about TPMS AEDK2953

Miscellaneous

Pocket Card "Electronic Diagnostic Codes" NEEG2500Chart "Practical Pressure Conversions" SEES5677"Cleaning Rear Axle Housing Assemblies (785/789)" SEBF8366Training CD-ROM "Caterpillar Electronic Technician (ET)for Off-highway Trucks" SERV7003Training CD-ROM "Truck Production Management System (TPMS)for Off-highway Trucks" SERV7004

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TABLE OF CONTENTS

INTRODUCTION ........................................................................................................................7

MAINTENANCE .......................................................................................................................11

OPERATOR'S STATION............................................................................................................38

MONITORING SYSTEM..........................................................................................................47Messenger Display Module ..................................................................................................52Advisor/VIMS Display .........................................................................................................63

ENGINE......................................................................................................................................83Engine Electronic Control System .......................................................................................84Engine Derates......................................................................................................................94Engine Compression Brake ................................................................................................101Cooling System...................................................................................................................106Lubrication System.............................................................................................................108Fuel System.........................................................................................................................109Air Intake and Exhaust System ..........................................................................................116

POWER TRAIN .......................................................................................................................124Torque Converter Hydraulic System ..................................................................................127Transmission Hydraulic System .........................................................................................138Rear Axle ............................................................................................................................150Transmission/Chassis Electronic Control System ..............................................................152

STEERING SYSTEM ..............................................................................................................163

HOIST SYSTEM......................................................................................................................177

BRAKE SYSTEM ....................................................................................................................197Brake Electronic Control System .......................................................................................224Automatic Retarder Control System...................................................................................229Traction Control System.....................................................................................................231

CONCLUSION.........................................................................................................................238

VISUAL LIST ..........................................................................................................................239

HYDRAULIC SCHEMATIC COLOR CODE.........................................................................242

HANDOUTS.............................................................................................................................243

POSTTEST ...............................................................................................................................268

POSTTEST ANSWERS ...........................................................................................................272

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NOTES

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INTRODUCTION

Shown is the right side of a 777F Truck. The fuel tank is located on the right side of the truck.

The 777F Truck comes standard with oil-cooled multiple disc brakes, front and rear. Frontcaliper type disc brakes are available as an option.

The major features added to the 777F Truck are: the new cab, the Messenger or VIMS Advisormonitoring system, the Tier 2 compliant C32 ACERT™ engine and cooling system, the ECPCtransmission, and the hydraulic brakes.

Some of the specifications of the 777F Truck are:

- Serial No. Prefix: JRP- Empty weight: 73976 kg (163090 lb)- Load carrying capacity: 90.9 tonnes (100 tons)- Gross Machine Weight (GMW): 163293 kg (360000 lb)- Length: 10.5 m (34.5 ft) - Operating Width: 6.5 m (21.3 ft)- Height: 5.2 m (17.0 ft)- Body Up Height: 10.4 m (34.0 ft)- Top speed, loaded: 64.5 km/h (40.1 mph)

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777F (JRP) OFF-HIGHWAY TRUCKINTRODUCTION

© 2006 Caterpillar Inc.

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Shown is the left side of a 777F Truck. The hydraulic tank group is visible. The hydraulic tankgroup consists of two separate tanks: the hoist, brake, and torque converter hydraulic tank(front) and the transmission hydraulic tank (rear). The transmission hydraulic system isseparated from all of the other hydraulic systems.

The Individual Clutch Modulation (ICM) transmission has been replaced with Electronic ClutchPressure Control (ECPC) transmission. The Chassis/Transmission Electronic Control Systemcontrols most of the same functions as on the 777D truck.

The air system has been eliminated on the 777F Truck. The brakes are completely hydraulic.

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Shown is the front of a 777F Truck. The 777F Truck uses a Next Generation Modular Radiator(NGMR). Its modular design, similar to the previous folded core radiator, permits easy removalof a single core without having to remove the entire radiator.

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Shown is the rear of a 777F Truck. Two body options are available for the 777F Truck:

- A dual-slope steel design with a "V" bottom main floor to reduce shock loading, centerthe load, and reduce spills.

- The dual-slope steel body above, with the addition of a rubber liner for increasedresistance to impact and wear.

All internal wear surfaces of the truck body are made with 400 Brinell hardness steel. The steelattachment body liner is also made with 400 Brinell hardness steel. The external components ofthe body are made of steel with a yield strength of 6205 bar (90000 psi). The rubber liner isone-fifth the density of steel, but absorbs impact four times better. The rear suspensioncylinders absorb bending and twisting stresses rather than transmitting them to the main frame.

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MAINTENANCE

Before working on or operating the truck, read the Operation and Maintenance Manualthoroughly for information on safety, maintenance, and operating techniques.

Safety precautions and Warnings are provided in the manual and on the truck. Be sure toidentify and understand all symbols before starting the truck.

The first step to perform when approaching the truck is to make a thorough walk aroundinspection. Look around and under the truck for loose or missing bolts, trash build-up and forcoolant, fuel or oil leaks. Look for indications of cracks. Pay close attention to high stressareas as shown in the Operation and Maintenance Manual.

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The following list identifies the items that must be serviced every 10 Hours or Daily.

- Walk-Around Inspection: Check for loose or missing bolts, leaks, trash build-up, andcracks in frame structures and body support pads.

- Back-up alarm: test- Brakes, indicators, gauges: test- Braking system: test- Coolant level- Differential / final drive oil level- Engine air filter service indicator- Engine oil level- Engine oil level (ORS)

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- Engine oil level: log additions- Fuel filter: drain water separator- Fuel tank: drain water / sediment- Hoist, converter, brake oil level- Seat belt: inspect- Secondary steering: test- Steering system oil level- Transmission oil level

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The front wheel bearing oil level is checked and filled by removing the plug (1) in the center ofthe wheel bearing cover. The oil should be level with the bottom of the plug hole. The fill plugis a magnetic plug. Inspect the fill plug weekly for metal particles. If any metal particles arefound, remove the wheel cover and inspect the bearings for wear. When draining the oil, rotatethe wheel so the drain plug (2) is at its lowest position.

The service interval for changing the front wheel bearing oil is 500 hours.

Use Final Drive and Axle Oil (FDAO) or commercial FD-1. As a substitute, TransmissionDrive Train Oil (TDTO) with a commercial TO-4 may be used.

Check the tire inflation pressure. Operating the truck with the wrong tire inflation pressure cancause heat build-up in the tire and accelerate tire wear. Caterpillar recommends inflating tireswith dry nitrogen instead of air to reduce heat build-up and potential combustion. Nitrogen alsoslows rubber deterioration and rim corrosion.

NOTE: Care must be taken to ensure that fluids are contained while performing anyinspection, maintenance, testing, adjusting, and repair of the machine. Be prepared tocollect the fluid in suitable containers before opening any compartment ordisassembling any component containing fluids. Refer to the "Tools and Shop ProductsGuide" (Form NENG2500) for tools and supplies suitable to collect and contain fluidsin Caterpillar machines. Dispose of fluids according to local regulations and mandates.

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Check the front suspension cylinders for leaks or structural damage. Check the chargecondition of the front suspension cylinders when the truck is empty and on level ground.Measure the charge height of the suspension cylinders and compare the dimension with thedimension that was recorded the last time the cylinders were charged. Recharge the cylinderswith oil and nitrogen if necessary.

A grease outlet fitting (arrow) is located on one side of each front suspension cylinder. Thegrease supply fitting is located on the opposite side of the suspension cylinder. No grease outletfittings should be located on the same side of the suspension cylinder as the grease fill location.Having an outlet fitting on the same side of the suspension cylinder as the grease fill locationwill prevent proper lubrication of the cylinder.

Make sure that grease is flowing from the outlet fittings to verify that the suspension cylindersare being lubricated and that the pressure in the cylinders is not excessive.

NOTE: For more detailed information on servicing the suspension system, refer to theSpecial Instruction "Suspension Cylinder Servicing" (Form SEHS9411).

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If the machine is equipped with the optional caliper type front brakes, inspect the brake linings (1) for wear. The thickness of the brake linings (not including carrier) must not be lessthan 3.15 mm (.125 in). Measure the lining at both ends because one end can wear more thanthe other.

The clearance between the brake carrier guide pins (2) and the brake disc (3) must not be lessthan 1.5 ± 0.5 mm (.06 ± .02 in.).

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The primary fuel filter (1) is mounted between the right front wheel and the engine cooling fan.A reusable fuel/water separator mounts directly to the filter element. Periodically open thevalve (2) under the separator bowl and drain any water into an approved container.

After changing fuel filters, hold the switch (3) upward to activate the electric fuel primingpump to refill the fuel lines and filters with fuel.

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The dual engine oil filters (1) are located on the right front of the engine. Engine oil samplescan be taken at the S•O•S tap (2) located on the front of the oil filter base.

The secondary fuel filter (3) is located at the right front of the engine, in front of the engine oilfilters.

A fuel filter bypass switch (4) is located on the filter base. The bypass switch provides an inputsignal to the Engine ECM indicating if the filters are restricted.

Jacket water coolant samples can be taken at the Scheduled Oil Sampling (S•O•S) coolantanalysis tap (5). The coolant tap is located behind the engine oil filters. The bottom illustrationshows the coolant tap with the filter removed.

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The transmission filters (1) are located behind the fuel tank and under the center tube.

Transmission oil samples can be taken at the S•O•S tap (2).

The oil filter bypass switch (3) provides input signals to the Transmission/Chassis ECM. TheECM sends a signal to the monitoring system in the cab to warn the operator when the filter isrestricted.

A pressure test port (4) is available for monitoring charge pressure for the transmission controlvalves.

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Located in front of the fuel tank on the right side of the truck is the torque converter chargingfilter (1).

Hoist, converter, and brake oil samples can be taken at the S•O•S tap (2) at the base of thefilter.

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The fuel tank is located on the right side of the truck. The fuel level sight gauge (1) is used tocheck the fuel level during the walk around inspection. A fuel level sender is located on thefuel level sight gauge. The fuel level sender provides input signals to the monitoring system,which informs the operator of the fuel level.

Open the drain valve below the tank to remove condensation and sediment from the fuel tank.

Inspect the condition of the fuel tank breather (above tank) and the fuel fill cap (2) at regularintervals.

Fuel can be added at the attachment quick service fuel fill connector (3).

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The rear axles are equipped with planetary-type final drives. Rotate the final drive until thedrain plug (1) is at the lowest position, as shown. The final drive oil level is checked and filledby removing the magnetic plug (2). The oil should be level with the bottom of the plug hole.Fill the rear axle housing with oil before filling the final drives with oil. Allow enough time forthe oil to settle in all of the compartments. This time allowance can be as much as 20 minutesduring cold temperatures. The oil is drained by removing the drain plug.

The magnetic inspection plugs should be removed weekly from the final drives and checked formetal particles. For some conditions, checking the magnetic plugs is the only way to identify aproblem which may exist.

Use FDAO (Final Drive and Axle Oil) or Transmission Drive Train Oil (TDTO) with aspecification of TO-4 or newer. These oils provide:

- Maximum frictional capability required for gears- Increased lubrication capability for bearings

NOTE: The rear axle is a common sump for the differential and both final drives. If afinal drive or the differential fails, the other final drive components must also bechecked for contamination and then flushed. Failure to completely flush the rear axleafter a failure can cause a repeat failure within a short time.

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Check the differential oil level by removing the magnetic inspection plug (1). The oil should belevel with the bottom of the fill plug opening.

Inspect the rear suspension cylinders for leaks or structural damage. Check the chargecondition of the rear suspension cylinders when the truck is empty and on level ground.Measure the charge height of the suspension cylinders, and compare the dimension with thedimension that was recorded the last time the cylinders were charged. Recharge the cylinders ifnecessary.

Inspect the condition of the rear axle breather (2) at regular intervals. The breather preventspressure from building up in the axle housing. Excessive pressure in the axle housing cancause brake cooling oil to leak through the Duo-Cone seals in the wheel brake assemblies.

NOTE: For more detailed information on servicing the suspension system, refer to theSpecial Instruction "Suspension Cylinder Servicing" (Form SEHS9411).

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The body up retaining pins are stored inside a cross-tube (1) in a body support beam directlyabove the retaining bracket (2). When work is to be performed while the body is raised, thebody up retaining pins must be installed through the holes in the body retaining bracket and therear frame support (3) to hold the body in the raised position. The body is shown in thelowered position.

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Shown are the transmission hydraulic tank (1) and the hoist, converter, and brake hydraulic tank (2). Both tanks are equipped with oil level sight gauges.

The oil level of both hydraulic tanks should first be checked with cold oil and the enginestopped. The level should again be checked with warm oil and the engine running.

The lower sight gauge (3) on the hoist, converter, and brake hydraulic tank can be used tocheck the tank level when the hoist cylinders are in the RAISED position. When the hoistcylinders are lowered, the hydraulic oil level will increase. After the hoist cylinders arelowered, check the hydraulic tank oil level with the upper sight gauge (4).

Check lower transmission oil sight gauge (5) with the engine off and oil cold. Use the uppergauge (6) with engine at idle and oil warm.

Inspect the hoist, converter, and brake hydraulic tank breather for plugging. The breather islocated on the frame rail above the hydraulic tank.

Inspect the condition of both hydraulic tank fill cap vents (located on top of the tank) at regularintervals.

When filling the hydraulic tanks after an oil change, fill the tanks with oil to the FULL COLDmark on the sight gauge. Turn on the engine manual shutdown switch so the engine will notstart. Crank the engine for approximately 15 seconds. The oil level will decrease as oil fills thehydraulic systems. Add more oil to the tanks to raise the oil level to the FULL COLD mark.Crank the engine for an additional 15 seconds. Repeat this step as required until the oil levelstabilizes at the FULL COLD mark.

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Turn off the engine manual shutdown switch and start the engine. Warm the hydraulic oil. Addmore oil to the tank as required to raise the oil level to the FULL WARM mark.

In both tanks, use only Transmission Drive Train Oil (TDTO) with a specification of TO-4 ornewer.

TDTO TO-4 oil has the following features:

- Provides maximum frictional capability required for clutch discs used in the transmission,torque converter and brakes.

- Increases rimpull because of reduced slippage.

- Increases brake holding capability by reducing brake slippage.

- Controls brake chatter.

- Provides maximum frictional capability required for gears.

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Before climbing the truck ladder, make sure that the manual engine shutdown switch (1) isOFF. The switch is located below the cab at the base of the left stairway.

The engine will not start if the manual shutdown switch is ON. If necessary, the switch can beused to stop the engine from the ground level.

The access light switch (2) is used to turn on or turn off the lighting in the area around thestairs. There is a second access light switch on the left side of the dash in the cab.

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While climbing the ladder, make a thorough inspection of the radiator. Be sure that no debrisor dirt is trapped in the radiator cores.

The battery disconnect switch is located under a cover (1) on the front bumper near the rightaccess ladder. If the machine is being parked for an extended period (overnight, etc.) turn offthe disconnect switch and remove the key.

The machine lockout and engine lockout switches are located behind an access cover (2)between the radiator cowling and the right stairway.

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This illustration shows the engine disconnect switch (1) and the auxiliary start receptacle (2).

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The engine lockout control switch (1) allows the engine to be safely locked out while service isperformed. The engine must be stopped to activate the engine lockout mode. When the enginelockout mode is activated, the following conditions exist:

- The engine starter is disabled.

- The secondary steering is disabled.

- The prelube function is disabled.

The following conditions must be met before the engine lockout mode will activate:

- The transmission control must be in the PARK position.

- The engine must be OFF.

When the switch is activated, one of the following results will occur:

- The indicator lamp (2) will illuminate continuously to indicate that the machine is in theengine lockout mode.

- The indicator lamp will flash to indicate that the engine lockout mode will not activateuntil the transmission control is in the PARK position and the engine is OFF.

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The machine lockout control switch (3) allows the machine to be safely locked out whileservice is performed. When the machine lockout mode is activated, the following conditionsexist:

- The engine will start.

- The transmission is disabled.

- The hoist is disabled.

- The steering is disabled.

- The machine lockout mode indicator (4) will illuminate after the key start switch isturned on.

NOTE: The lockout mode indicator on the dash panel will illuminate when the enginelockout control or the machine lockout control is activated.

Also located near the lockout switches are the following circuit breakers:

- 90 Amp Alternator (5)

- 15 Amp Engine (6)

- 80 Amp Starter Solenoid (7)

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The batteries are located inside the front bumper, at the base of the radiator cowling (1).Inspect the battery connections for corrosion or damage. Keep the battery terminals clean andcoated with petroleum jelly.

Inspect the electrolyte level in each battery cell, except maintenance free batteries. Maintainthe level to the bottom of the fill openings with distilled water.

The coolant level on the 777F is checked with the jacket water coolant sight gauge (2) locatedbelow the cab on the side of the front cowling. Coolant is added by removing the radiator cap (3) located inside an access door on the upper deck.

The water used in the cooling system is critical for good cooling system performance. Usedistilled or deionized water whenever possible to prevent acids or scale deposits in the coolingsystem. Acids and scale deposits result from contaminants that are found in most commonwater sources.

Never use water alone. All water is corrosive at engine operating temperatures without coolantadditives. Also, water alone has none of the lubrication properties that are required for waterpump seals.

Cat trucks are filled at the factory with Extended Life Coolant (ELC). If ELC is maintained inthe radiator, it is not necessary to use a supplemental coolant additive. Do not use aconventional coolant to top-off a system filled with Cat ELC.

An acceptable substitute for ELC is a Cat DEAC (Diesel Engine AntiFreeze/Coolant) or acommercial heavy-duty coolant/antifreeze that meets ASTM D4985 or ASTM D6210specifications.

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The steering system hydraulic tank is located on the right platform.

Check the steering system oil level at the sight gauge (1), on the side of the tank.

The steering system oil filter (2) cleans the oil before it enters the hydraulic tank.

The steering system uses a pressure compensated piston-type pump mounted to the rear of theengine. Case drain oil from the steering pump returns to the steering tank through a case drainfilter (3).

Before removing the fill cap (4) to add oil to the steering system, depress the pressure releasebutton (5) on top of the breather to release any pressure from the tank.

The steering system filter base and the case drain filter base have bypass valves that allow thesteering oil to bypass the filters if they are plugged.

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Shown are the air intake system components. Check the air filter restriction indicator (1). Ifthe yellow piston is in the red zone, the air filters are restricted and must be serviced.

The air filter housing covers serve as the precleaner assemblies. When servicing the filterelements, clean the precleaners (2) and dust valves (3) using air or water pressure, or detergentwash.

The dust valve is OPEN when the engine is OFF and closes when the engine is running. Thedust valve must be flexible and closed when the engine is running or the precleaner will notfunction properly and the air filters will have a shortened life.

Two filter elements are installed in the filter housings. The large element is the primaryelement and the small element is the secondary element.

Air intake system tips:

- The primary element can be cleaned a maximum of six times.

- Never clean the secondary element for reuse. Always replace the secondary element.

- Air filter restriction causes black exhaust smoke and low power.

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The engine oil level dipstick (1) and the engine oil fill tube (2) are located inside the accesscover for the air filters. Check the engine oil level with the dipstick and add engine oil at thefill tube.

Caterpillar recommends multigrade Diesel Engine Oil (DEO) with a specification of ECF-1.API CH-4, CI-4, and CI-4 Plus oils are only acceptable if they meet ECF-1 specifications.

DEO oils with a CG-4 specification are acceptable, but should be limited to 250-hour oilchange intervals. CF and older oils should not be used in Caterpillar diesel engines.

Cat ECF-1 Specification was established by Caterpillar in 2003 and requires excellent sootdispersion, wear control, and piston deposit control.

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To check the fluid level of the windshield washer reservoir, open the access door located at theleft rear of the cab, behind the cab door. Open the filler cap (1) to check the fluid level and fillas necessary.

To the left of the filler spout is the air conditioner filter (2). Clean or replace the filter elementwhen a reduction of circulation in the cab is noticed.

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The remaining 10 Hours or Daily checks are performed in the operator's compartment:

- Brakes: Check operation

- Indicators and gauges: Test operation

- Seat belt: Inspect

- Back-up alarm: Test operation

- Secondary steering: Test operation

The service brakes are checked by depressing the pedal (1) and placing the shift lever in FIRSTFORWARD. Accelerate the engine until the truck moves. The truck must not move below1200 rpm. This procedure should be repeated to test the secondary brakes by depressing thesecondary brake pedal (2).

The cab air filter (3) is located inside the cab door, in the left-rear corner behind the trainer seat.Clean or replace the cab fresh air filter when necessary.

NOTE: Refer to the Operation and Maintenance Manual for information on theremaining tests performed in the cab.

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This illustration shows the cab air filter (1) located behind the trainer seat (2).

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OPERATOR'S STATION

Shown is a view of the 777F operator compartment. The operator's station for the 777F hasbeen changed to improve operator comfort and ergonomics. The operator seat (1) is centered inthe cab with the trainer's seat (2) positioned to the left.

The hoist control lever (3) is now on the right console next to the transmission control lever (4).

The 777F is equipped with a standard Messenger Monitoring System or optional VIMS/AdvisorMonitoring System (shown).

The optional Caterpillar Work Area Vision System (WAVS) is a closed circuit video monitoringsystem. WAVS consists of a 178mm (7 inch) LCD color display (5) and may include one, two,or three cameras. The display is mounted in the machine cab. The cameras are mounted on theframe of the machine. The location of the camera(s) is dependent on the machine type.

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The Truck Production Management System (TPMS) on the 777F is controlled by a TPMS ECMif the machine is equipped with Messenger or a VIMS ECM if the machine is equipped withVIMS/Advisor. There are two sets of TPMS external loading lamps on the truck. One set oflamps is on the left side of the cab (arrow) and the other set is on the right platform. The lampsare green and red. The lamps inform the loader operator of the loading progress toward a targetpayload weight. The lamps are active only during the loading cycle and are off at all othertimes.

During loading, the green (continue loading) lamps will be ON until the payload is 95% of thetarget weight setting. Then, the red (stop loading) lamp will light. A "last pass" indication canbe programmed into the system. With last pass indication, the TPMS calculates an averageloader pass size and predicts payload weight. If the predicted weight after the NEXT loaderpass will be above 95% of the target weight setting, the red lamps FLASH. The red lamps willbe ON continuously after the last pass (when fully loaded). A minimum of three loader passesare required for the "last pass" indication option to function correctly. The actual measuredweight of the material in the truck body is displayed on the Messenger display or theVIMS/Advisor display.

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Located on the left side of the front panel are:

- Telescopic/tilt steering column adjustment lever (1): Push for telescoping and pull for tilt.

- Intermittent wiper/washer, turn signal control, and dimmer switch (2).

- Steering wheel mounted electric horn control (3).

- Light switches and hazard warning switch (4).

The instrument panel (5) includes a tachometer, four gauges, and several indicators that displaythe machine systems status. An LCD screen displays the service hour meter, machine groundspeed, actual gear, and direction.

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Located on the right side of the steering column is the retarder lever (1). The retarder lever isused to modulate engagement of the service brakes. The retarder lever engages the front andrear brakes on trucks with the standard oil-cooled front brakes but engages but only the rearbrakes on trucks with the optional caliper disc front brakes. The retarder lever can control themodulation of the service brakes more precisely than the service brake pedal located on the cabfloor.

Located on the dash to the right of the retarder lever are the key start switch (2), fan speedswitch (3), temperature variable knob (4), air conditioner switch (5), and cigarette lighter (6).Above the HVAC controls is the optional VIMS/Advisor display (7).

Switches to the left of the VIMS/Advisor display are the ARC ON/OFF switch (8), compressionbrake switch (9), and front brake switch (10) (if equipped).

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To the right of the operator's seat is the shift console which contains the transmission shift lever (1) and the hoist control lever (2). The 777F truck has SEVEN speeds FORWARD andONE REVERSE.

The top gear limit and body up gear limit are programmable through the Transmission/ChassisECM. The top gear limit can be changed from THIRD to SEVENTH. The body up gear limitcan be changed from FIRST to THIRD.

The 777F truck hoist system is electronically controlled. The hoist control lever activates thefour positions of the hoist control valve. The four positions are: RAISE, HOLD, FLOAT, andLOWER.

A fifth position of the hoist valve is called the SNUB position. The operator does not havecontrol over the SNUB position. The body up switch controls the SNUB position of the hoistvalve. When the body is lowered, just before the body contacts the frame, theTransmission/Chassis ECM signals the hoist solenoids to move the hoist valve spool to theSNUB position. In the SNUB position, the body float speed is reduced to prevent hard contactof the body with the frame.

The truck should normally be operated with the hoist lever in the FLOAT position. Travelingwith the hoist in the FLOAT position will make sure the weight of the body is on the frame andbody pads and not on the hoist cylinders. The hoist valve will actually be in the SNUBposition.

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If the transmission is in REVERSE when the body is being raised, the hoist lever sensor is usedto shift the transmission to NEUTRAL. The transmission will remain in NEUTRAL until:

1. the hoist lever is moved into the HOLD or FLOAT position; and

2. the shift lever has been cycled into and out of NEUTRAL.

The hoist lever is also used to start a new TPMS cycle.

NOTE: If the truck is started with the body raised and the hoist lever in FLOAT, thelever must be moved into HOLD and then FLOAT before the body will lower.

The throttle backup and throttle lock switch (3), the WAVS alternate camera system switch (4)(if equipped), and a 12V power port (5) are also located on the shift console.

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The overhead console can be equipped with four switches. The optional heated mirrors switch (1) controls the heated mirrors.

The TCS test switch (2) is used to perform the TCS test when the switch is held.

The brake release/secondary steering switch (3) manually activates the brake release andsecondary steering pump when the switch is held.

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Located on the floor of the cab are:

- Secondary brake pedal (1): Used to modulate application of the parking brakes on therear wheels. A position sensor is attached to the secondary brake pedal that providesinput signals to the Brake ECM.

- Service brake pedal (2): The service brake pedal is used to modulate engagement of theservice brakes on all four wheels if the front brake ON/OFF switch is in the ON position.A position sensor is attached to the service brake pedal that provides input signals to theBrake ECM.

- Throttle pedal (3): A throttle position sensor is attached to the throttle pedal. The throttleposition sensor provides the throttle position input signals to the Engine ECM.

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Located behind the trainer's seat are the fuse panels (1), the Cat ET service port (2), the TPMSor VIMS service port (3), the Product Link service port (4), a 12V power receptacle (5), and the 20 amp heater/air conditioner fan circuit breaker (6).

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MONITORING SYSTEM

The monitoring system on the 777F Off-highway Trucks monitors various machine systems andthen conveys the machine status to the operator. The 777F can be equipped with the standardmonitoring system which includes a Messenger display module, or the optional monitoringsystem which includes a VIMS/Advisor display module.

Both monitoring systems include an instrument cluster. The instrument cluster is a cab displaythat shows the operator the status of various machine parameters and alerts the operator ofspecific machine conditions.

The ECMs and monitor display modules communicate over the Cat Data Link. The displaymodules communicate with the instrument cluster over the Can Data Link.

The monitoring system receives information from machine switches and sensors via the ECMsshown in this illustration of the Machine Electronic Control System.

The 777F can also have the following attachments: Minestar, RAC, Product Link,Inclinometer, Telemetry antenna, and GPS antenna.

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The instrument cluster (1) and optional VIMS/Advisor display panel (2) are shown is thisillustration. The standard Messenger module (not shown) is installed in the same location asthe VIMS/Advisor display panel.

Problems from the machine systems are classified into four warning categories (1, 2, 2S, and 3)similar to other Caterpillar monitoring systems.

During the normal operation mode and the menu mode, the Messenger or VIMS/Advisordisplay may be interrupted by a warning message. Warning messages are displayed whenimportant instructions or information need to be displayed.

The Messenger or VIMS/Advisor provides three Warning Categories. The first categoryrequires only operator awareness. The second category states that the operation of the machineand the maintenance procedure of the machine must be changed. The third Warning Categorystates that the machine must be safely shut down immediately.

Warning Category 1For a Category 1 Warning, an indicator light will illuminate or a gauge will be in the red zone.The indicator that illuminates or the gauge that is in the red zone identifies the machine systemthat needs attention. The "OK" key on the Messenger or VIMS/Advisor panel can be used toacknowledge the warning. Some warnings will be silenced for a predetermined period. Afterthis time period, if the abnormal condition is still present, the warning will reappear.

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Warning Category 2For a Category 2 Warning, an indicator will illuminate or a gauge will indicate in the red zone,the action light will flash, and a popup screen appears on the Messenger or VIMS/Advisordisplay screen. A Category 2 warning alerts the operator that a change in machine operation isrequired to avoid possible damage to the indicated system. The "OK" key on the Messenger orVIMS/Advisor panel can be used to acknowledge the warning. Some warnings will be silencedfor a predetermined period. After this time period, if the abnormal condition is still present, thewarning will reappear.

Warning Category 2-SFor a Category 2-S Warning, an indicator will illuminate or a gauge will indicate in the redzone, the action light will flash, a popup screen appears on the Messenger or VIMS/Advisordisplay screen, and an action alarm will sound continuously. The 2-S Warning indicates aSEVERE Category 2 Warning. A Category 2-S Warning alerts the operator to immediatelychange the operation of the machine to avoid possible damage to the indicated system. Whenthe change in operation is made to an acceptable condition, the action alarm will turn off.

Warning Category 3For a Category 3 Warning, an indicator will illuminate or a gauge will indicate in the red zone,the action light will flash, a popup screen appears on the Messenger or VIMS/Advisor displayscreen, and an action alarm will sound intermittently. A Category 3 Warning alerts the operatorthat the machine must be safely shut down immediately to avoid damage to the machine orprevent personal injury. Some Category 3 Warnings cannot be stopped by pressing the "OK"key.

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Shown is the Instrument Cluster located in the center of the front dash panel. The InstrumentCluster includes 18 dash indicators, five analog gauges, and an LCD digital display (1). TheLCD display window in the lower center of the dash includes the truck speed, gear, anddirection on the top of the display and the service hour meter on the bottom of the display.

The five parameters monitored by the analog gauges are:

- Brake oil temperature (2)

- Engine coolant temperature (3)

- Engine speed (4)

- Torque Converter oil temperature (5)

- Fuel Level (6)

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The indicator lamps and gauges are shown in this illustration.

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Messenger Display Module

Shown is the standard Messenger display module, which is located in the right side of the frontdash. The purpose of the Messenger is to display relevant machine information to the operatoror service personnel. The Messenger display is used in conjunction with the instrument clusterto act as the monitoring system for the machine.

The Messenger has a menu structure that allows the user to access the desired machineinformation. The default screen will display under normal machine operating conditionswithout any intervention from the operator or service personnel.

This illustration shows the default screen of the Messenger module that shows the shift leverand the gear position. The default screen is displayed at machine start up and until the operatoror the technician navigates to another screen.

The Messenger consists of the display and four navigation buttons that are used to navigatethrough the menu structure. The button functions from left to right are as follows:

Back: Used to navigate to the previous screen that was accessed in the Messenger.

Left/Up: Allows the user to scroll left or up. Scroll direction is dependent on the specificdata that is being displayed on the screen.

Right/Down: Allows the user to scroll right or down. Scroll direction is dependent on thespecific data that is being displayed on the screen.

OK: Acts as a confirmation function for the Messenger.

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The Messenger Menu Screen is divided into three sections. The top section identifies the nameof the current menu. If the current name is split by a colon ":" then this indicates that the nameafter the colon ":" is the current menu and the name before the colon ":" is the parent menu ofthe current menu. The center section displays the current menu option that can be selected bypressing the OK button. The arrows at the left of the screen indicate whether you can scroll tothe next screen to see further menu options.

There are a total of five main menus that are available for navigation. Only one menu can bedisplayed at a time. The menus are accessed from the default menu by pressing the back arrowbutton. The five menus are:

- Performance

- Totals

- Settings

- Service

- Service mode

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This illustration of a performance screen submenu shows the engine coolant temperature andshift lever position.

A typical Messenger information screen normally displays the information in pairs. Theheaders at the top of the screen identify the information. The current values are displayedbelow the headers. The arrows at the left of the screen indicate whether you can scroll to thenext screen to see additional information.

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The Performance menu allows the operator or technician to view two pages of information.These pages of information monitor vital machine system data during machine operation. Thisinformation can only be viewed. The Performance menu uses two screens to show the real timestatus of the information listed above on the right side of the illustration.

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The Totals main menu allows the operator or the technician to access information about themachine systems. The totals data can be used to determine when scheduled maintenance isrequired.

The Totals menu shows accumulated values and includes two submenus. The two submenusare Payload and Machine.

The Payload and Machine submenus display the information listed on the right side of theabove illustration.

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Parameters are normally adjusted for specific operating conditions, operator preferences, andmachine operating efficiency. The machine setup affects the parameters that are displayed. Theattachments that are on the machine determine the software that is contained in the ECMs.Messenger looks at the software versions to determine the parameters that will be displayed andthe parameters that will be variable.

NOTE: Cat ET can also be used to access the parameters.

The Settings menu allows the user to adjust the parameters for the following:

- Messenger Display

- Machine Identification

- Transmission Operation

- Brake Operation

- Payload Operation

- Engine Operation

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The Messenger Display parameters relate to the operator’s preferences for the Messengerdisplay. The following parameters may be adjusted:

- Language: Six standard languages (other languages available).

- Units: Metric or English.

- Contrast: Screen contrast.

- Headlights On: Screen brightness with headlights ON.

- Headlights Off: Screen brightness with headlights OFF.

The Machine settings allow the user to set the machine serial number. The followingparameters may be adjusted:

- Product ID: Allows the user to set the machine serial number (password protected).

- Equipment ID: Allows the name of the truck to be changed (password protected).

The Transmission setting allows the following parameters to be adjusted:

- Top Gear Limit: Allows the user to set the highest gear performance level.

- Body Up Gear Limit: Adjusts the gear limit during truck operation when the body israised.

- Machine Speed Limit: Sets the highest truck speed.

- Fuel Economy Mode: Allows the fuel usage to be changed.

- Machine Overload Speed Limit: Limits transmission gear and engine speed whenexcessive payloads are detected (if machine is equipped with TPMS).

The Brake setting allows the user to set the desired ARC speed and is password protected.

The Payload menu allows the configuration of the Payload settings and is password protected.The Payload settings include the following:

- Target Payload: Read and program the truck target payload.

- Overload Limit: Read and program the percent overload.

- Green TPMS Lamp: Read and program the installation of the green TPMS lamp.

- Red TPMS Lamp: Read and program the installation of the red TPMS lamp.

- Last Pass Enabled: Read and program the installation of the Last Pass indicator. TheLast Pass indicator informs the shovel operator of the last load before the payload is overthe rated load.

The Engine setting allows the user to change the ether solenoid configuration to "No EtherSolenoid Installed" or "Continuous Flow" and is password protected.

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The Service menu allows the technician to access the machine parameters. The technician mayalso make selections for viewing or clearing logged events or codes.

The Service menu will allow the technician to view data for the following systems: the brake,the steering, the implement, and the power train. The status of electronic components in themachine’s major systems can also be viewed. The Service menu option is displayed byselecting Service from the Main Menu. Press the Left/Up arrow button or the Right/Downarrow button until Service is displayed. Then press the OK button. The Service menu containsthe following six submenus:

- Diagnostic Events: Displays a complete list of all active and inactive event codes anddiagnostic codes.

- System Parameters: Allows the technician to view the status of system components.

- Calibrations: Allows the technician to perform a payload calibration. The payloadsystem must be calibrated if new TPMS software is installed or the suspension is charged.

- System Tests: Allows the user to perform a transmission stall test or a system self test onthe machine.

- Systems Information: Allows the user to display information on all of the ECMs installedon the machine, such as ECM Part Number, etc.

- Tattletale: The Messenger display module records the extreme value for each conditionof the machine that is monitored.

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These illustrations show the information available within the Diagnostic Events menu.

From the Service menu, use the appropriate arrow button to highlight the Diagnostic Eventsoption and press the OK button to access the Diagnostic Events. Select the View Diagnosticsdisplay by pressing the OK button. The View Diagnostics option will display a complete list ofcodes (bottom left illustration). Each line on the list will show the following information:

- SRC (Source ID)

- CODE

- OCC (Number of occurrences of the event or code)

- ACT (if the code is active or inactive).

Use the appropriate arrow button to highlight a diagnostic code or an event code on the list.Press the OK button to display the codes Detailed View (bottom right illustration). TheDetailed View will display a text message that shows the following information: reportingECM, failed component code, and explanation of the event.

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The technician can clear logged codes one at a time. Active codes are indicated with a markunder the "ACT" column. Active codes cannot be cleared until the faults have been corrected.To clear a code, access the Detailed View of the code, press the OK button and follow theprompts and directions.

NOTE: Only Level I and Level II codes may be cleared with Messenger. When a codeis cleared from Messenger, the memory from the reporting ECM is cleared. The code isnot cleared from the Messenger ECM. Once the code has been cleared from thereporting ECM, Messenger will update the code list. Messenger is an interface betweenthe technician and the machine ECMs.

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The Service Mode Password menu is used to enter the Service mode. The Service ModePassword protects certain features from access by the operator. Features that need to beprotected from the operator can be enabled or disabled with a password.

NOTE: For more information on the Messenger Monitoring System, refer to the 773F,775F, 777F Off-highway Truck Monitoring Systems Operation, Troubleshooting, Testing,and Adjusting Service Manual module (RENR8344).

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Advisor/VIMS Display

Shown above is the Advisor/VIMS graphical display module. It is located on the right side ofthe dash. It is the operator and technician’s interface with the Advisor Monitoring System,including VIMS. Information is displayed on a backlit LCD display screen.

The top portion of the screen is called the "Top Banner" and it displays vital machineinformation at all times. The Top Banner may display different information from machine tomachine, depending on the model and the attachments that are installed.

At the right of the display screen is a column of five user interface buttons. These buttons areused to navigate through the numerous Advisor screens, to make menu selections, or to enterdata. The five buttons, from top to bottom, are:

- LEFT/UP Arrow Button (1) - This button is used for screen navigation or data entry. It can beused:

• to scroll up a vertical list or scroll left across a horizontal list;

• to decrease a setting value, such as decreasing brightness/contrast.

- DOWN/RIGHT Arrow Button (2) - This button is also used for screen navigation or dataentry. It can be used:

• to scroll down a vertical list or scroll right across a horizontal list;

• to increase a setting value, such as increasing brightness/contrast.

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- BACK Button (3) - This button is used:

• to go up one level in a stair-step (hierarchical) menu structure, or to return to theprevious screen;

• as a backspace, or cancel key when the operator or technician wishes to delete enteredcharacters.

- HOME Button (4) - This button is used to return to the home menu screen, regardless of whatscreen is currently displayed.

- OK Button (5) - This button is used:

• to make selections from a screen;

• to confirm an entry, such as a password, or for saving an operator profile entry.

Navigation through the menus and sub-menus is accomplished by using the ARROW Buttonsto highlight the desired selection, then pressing the OK Button. The ARROW Buttons are alsoused to highlight a mode or to set a parameter. Pressing the OK Button selects that option.

NOTE: The left buttons are used to display a screen without scrolling. If a screen isselected and one of the left buttons is pressed and held for at least three seconds, thescreen is saved (programmed). Whenever the button is pressed again the "saved"screen will appear.

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Upon machine start-up (key ON), an introduction screen appears as shown in the topillustration and Advisor performs a self-test routine. After a few seconds the main screen willappear as shown in the bottom illustration.

NOTE: The time and date is set with VIMSpc software.

Also displayed to the right of the time and date is the inclinometer value.

53

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The illustration above shows a "pop-up" warning screen generated by the Transmission/ChassisECM and reported by Advisor. There may be more warning screens if there are any otheractive faults or events reported to Advisor by the Transmission/Chassis ECM, or any otherECM on the machine. Advisor will scroll through all of the warning screens generated by all ofthe active faults and events. Each of these warning screens must be individually acknowledgedby pressing the "OK" button.

Each of these warning screens contains the following information:

- The reporting ECM (in text)

- The reporting MID (module identifier, or ECM code)

- The ID (Component ID and Failure Mode Identifier)

- A text message stating the failed component

- A text message stating the failure mode of the component

- A prompt for the operator to acknowledge the warning

Acknowledging these warnings does not clear them from the reporting ECM's memory, butonly clears them from the screen, or "snoozes" them. The warnings remain an active event orfault until the problem is resolved. Advisor will display the message again after a pre-determined amount of time, depending on the severity of the event.

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56

Advisor’s menu structure is arranged in a stair-step, or hierarchical list format. When theoperator or technician selects an option from a menu or list, the resulting screen is one leveldown from that selection. More selections, or options, may be available from that screen aswell. There may also be more than one page of information or options to be displayed fromany level. This is indicated by the "More Options" icon, which may point left, right, up, ordown, depending upon how the data or list is arranged.

The illustration above shows the options that are available from Advisor's Home Menu screen.The Home Menu screen and its options will be displayed upon pressing the HOME button fromany screen within Advisor.

SERV1828 - 67 - Text Reference01/07

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The Operator menu allows the user to perform the following:

- Select a profile

- Create a profile

- Delete a profile

- View/save a current profile

- Factory Set (recalls default settings)

The profile of an operator is a saved set of preferences that is identified by a name. Once theprofile is created, the operator may associate various display settings and settings for the powertrain to that profile. After all of the parameters have been adjusted to the operator's preference,the operator may then save the parameters for future use.

57

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This illustration shows the options within the Operator Menu.

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The Service menu contains six submenus. The following is a list of the submenus:

- Diagnostics

- Calibrations

- System Information

- Tattletale

- System Tests

- Service Parameters

60

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This illustration shows the diagnostics submenu within the service menu.

The Active Events menu option shows the ECM and the service hours for each event. Thefollowing is a list of information that is displayed for the active event:

- Electronic Control Module

- Event Code

- Date of occurrence

- Time of occurrence

- Warning Level

- Number of occurrences

The Logged Events menu option shows the list of events and diagnostic codes that have beenrecorded. Logged events can only be cleared by downloading and resetting the VIMS ECMwith VIMSpc.

The Trigger Snapshot menu option allows the user to manually initiate a snapshot of the systemin addition to the snapshots that are already programmed. The snapshot will remain active untilthe time has elapsed.

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The Data Logger Start menu option allows the user to initiate the data logger. If theinformation for the data logger is being downloaded from the machine, the data logger cannotbe started. The operator can initiate and stop the data logger numerous times until the totaltime for logging the data is thirty minutes.

The Data Logger Reset menu option allows the user to reset the data logger, which clears all ofthe logged information. Thirty minutes will be available after the data logger has been reset.

NOTE: The Data Logger is the only onboard file that can be reset through the Advisordisplay. The Advisor must be either in the Service Mode or Cat ET must be connectedto the data link to reset the data logger. The VIMSpc software is not needed to reset thedata logger.

SERV1828 - 72 - Text Reference01/07

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SERV1828 - 73 - Text Reference01/07

These illustrations show four of the submenus within the service menu.

The Calibrations option consists of the Truck Payload and Inclinometer calibrations.

The System Information menu option allows the user to view the information for the followingmachine ECMs:

- Advisor

- Engine

- Transmission/Chassis

- Brake

- VIMS

The ECM information contains the following:

- ECM serial number

- Software part number

- Software release date

- Software description

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The following options are available under the tattletale menu:

- Active

- Brake Oil Temperature

- Engine Coolant Temperature

- Engine Speed

- Torque Converter Temperature

- Fuel Level

The Active option will display the tattletale value for each gauge. The five specific options willdisplay the tattletale value for the gauge that is specified.

NOTE: The tattletale is password protected. The value for each gauge is protectedfrom being cleared.

The System Tests option will allow the technician to perform the Stall Diagnostic Test or theSelf Test.

The instrument cluster will initiate a self test when the key start switch is moved to the STARTposition. The gauge needles will move to the maximum right position for 0.5 seconds and thenreturn to the minimum left position. This action prevents the gauge needles from circling to thebottom side of the gauge if the display is inverted.

SERV1828 - 74 - Text Reference01/07

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This illustration shows the Service Parameters submenu within the service menu.

The following Service Parameters options will be displayed:

- Sort By ECM

- Sort By Type

- All parameters

The Sort By ECM menu option allows the user to view the parameters that are associated witheach ECM. All of the parameters for the specific ECM are listed. The following ECMs can beselected:

- Advisor

- Engine

- Transmission/Chassis

- Brake

- VIMS

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The Sort By Type menu option allows the user to view the parameters that are associated withdifferent components. The following types of parameters can be chosen:

- Temperatures

- Pressures

- Speeds

- Filter Switches

- Operator Inputs

- Sensor Duty Cycles

- Totals

The All Parameters menu option allows the user to view the entire list of parameters.

SERV1828 - 76 - Text Reference01/07

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The Settings menu allows the user to view the parameters for the following the same as theMessenger Settings menu:

- Display Setup

- Machine

- Transmission/Chassis

- Brake

- VIMS (same as Messenger Payload submenu)

- Engine

65

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The Display Setup parameters relate to the operator’s preferences for the Advisor display. Thefollowing parameters may be adjusted:

- Language (same as Messenger)

- Units (same as Messenger)

- Contrast (same as Messenger)

- Headlights On (same as Messenger)

- Headlights Off (same as Messenger)

- Date format: (Advisor only)

- Time format: (Advisor only)

The Machine setting allows the user to set the machine serial number. The followingparameters may be adjusted and are the same as the Messenger Display:

- Product ID

- Equipment ID

The Transmission/Chassis setting allows the following parameters to be adjusted:

- Top Gear Limit (same as Messenger)

- Body Up Gear Limit (same as Messenger)

- Machine Speed Limit (same as Messenger)

- Fuel Economy Mode (same as Messenger)

- Machine Overload Speed Limit (same as Messenger)

- Load Count (Advisor only)

The Brake setting is the same as the Messenger display.

The VIMS/Payload menu allows the configuration of the Payload settings and is passwordprotected. The following payload settings are the same as the Messenger Display:

- Target Payload

- Overload Limit

- Green TPMS Lamp

- Red TPMS Lamp

- Last Pass Enabled

The Engine setting allows the user to change the ether solenoid configuration to "No EtherSolenoid Installed" or "Continuous Flow" and is the same as the Messenger Display.

SERV1828 - 78 - Text Reference01/07

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The Payload menu option is entered by selecting Payload from the Main menu. The Payloadmenu option allows the user to view the information for the payload. The user can view thefollowing information:

- Target for the payload

- Calculated gauge for the payload

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The Monitor menu option allows the user to view four parameters. The navigation button isused to select the parameter or view a different parameter. Press the OK button to obtain a listof available parameters.

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The Grade menu option allows the user to view the grade of the hill. The user can view thefollowing information:

- Percentage of the grade value

- Image of the truck that represents the grade

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The Service Mode menu option allows the user to enable and disable the service mode. Thepassword entry screen will appear if the password has been entered in Cat ET. The Advisorwill enter the service mode after the password has been entered correctly.

NOTE: For more information on the Advisor/VIMS Monitoring System, refer to the773F, 775F, 777F Off-highway Truck Vital Information Management System (VIMS)Systems Operation, Troubleshooting, Testing, and Adjusting Service Manual module(KENR5955).

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ENGINE

Shown is the C32 engine with ACERT™ Technology used in the 777F Off-highway Truck.

The engine performance specifications for the 777F Truck are:

- Serial No. Prefix: LJW- Performance spec: 0K5981- Gross power: 758 kW (1016 hp)- Full load rpm: 1750- High idle rpm: 1938 ± 10- Low idle rpm: 650- Overspeed rpm: 2800

This V-12 engine uses twin turbochargers, Air to Air AfterCooler (ATAAC) and MechanicalElectronic Unit Injection (MEUI) for power, reliability, and fuel economy. The C32 iscompliant with U.S. EPA Tier 2 and European Union Stage II emissions regulations.

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Engine Electronic Control System

Shown is the electronic control system component diagram for the C32 engine used in the 777FTruck. Fuel injection is controlled by the Engine Electronic Control Module (ECM).

Many electronic signals are sent to the Engine ECM by sensors, switches, and senders. TheEngine ECM analyzes these signals and sends signals to various output components. Outputcomponents can be relays, lamps, other controls, or solenoids.

For example, based on the various input signals, the Engine ECM determines when and for howlong to energize the injector solenoids. When the injector solenoids are energized determinesthe timing of the engine. How long the solenoids are energized determines the engine speed.

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Fuel injection and some other systems are controlled by the Engine ECM (1) located at thefront of the engine. Other systems controlled by the Engine ECM are: ether injection, enginestart function, engine oil pre-lubrication, variable speed Rockford fan, engine retarding, andengine derate.

The Engine ECM has two main connectors for diagnostics. The larger 120-pin connector (2)known as J2 connects to the engine harness. The smaller 70-pin connector (3) is identified onschematics as J1 and connects to the machine harness.

A 2-pin timing calibration connector is located to the right of the ECM. If the engine requirestiming calibration, a timing calibration sensor (magnetic pickup) is installed in the flywheelhousing and connected to the timing calibration connector.

Using the Caterpillar ET (Cat ET) service tool, timing calibration is performed automaticallyfor the speed/timing sensors. This step is performed to avoid instability and ensures that nobacklash is present in the timing gears during the calibration process. Timing calibrationimproves fuel injection accuracy by correcting for any slight tolerances between the crankshaft,timing gears, and timing wheel. Timing calibration is normally performed after ECMreplacement, cam or crank sensor replacement, or timing wheel replacement.

Occasionally, Caterpillar will make changes to the internal software that controls theperformance of the engine. These changes can be performed by using the WinFlash program inCat ET. Cat ET is used to diagnose and program the electronic controls used in Off-highwayTrucks. If using the WinFlash program, a "flash" file must be obtained from Caterpillar anduploaded to the ECM.

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The left intake air temperature sensor (1) and right intake air temperature sensor (2) are locatedon top of the engine. The intake air temperature sensors produce an analog signal that ismonitored by the Engine ECM. The ECM monitors intake air temperature for derating theengine at high temperatures, for engine shutdown at high temperatures, and for signaling themonitoring system in the event of a problem.

NOTE: If a high temperature event is severe enough, the monitoring system will issue aLevel 3 warning. The operator must park the machine as soon as possible. When theEngine ECM determines that the ground speed is zero and the transmission is in PARK,the engine will automatically shut down.

The coolant temperature sensor (3) is located on top of the engine toward the front left side.The coolant temperature sensor is an analog sensor that is monitored by the Engine ECM.When the coolant temperature is too high, the Engine ECM will signal the monitoring system todisplay a warning.

The Engine ECM also uses the coolant temperature sensor information for cold mode functionssuch as timing changes, elevated idle, cold cylinder cut-out, and ether injection.

The left turbo outlet pressure sensor (4) and right turbo outlet pressure sensor (5) are used forcalculating boost.

The atmospheric pressure sensor (6) is located on top of the engine toward the front right side.The atmospheric pressure sensor is an analog sensor that is monitored by the Engine ECM.The ECM monitors atmospheric pressure for the following: altitude derate, air inlet restrictionderate, and calibration reference for other sensors.

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The crankshaft speed/timing sensor (1) is located on the lower left of the engine toward thefront side. The crank sensor measures engine speed and timing for control of the timing anddelivery of fuel to each of the engine's cylinders. Sensing engine speed allows engine speedgoverning, fuel limiting, and fuel injection timing. If the crank speed/timing sensor fails, thecam speed/timing sensor allows for continuous operation.

The oil pressure sensor (2) is located on the left side of the engine. The oil pressure sensor isan analog sensor that is monitored by the Engine ECM. When the oil pressure is too low, theEngine ECM will signal the monitoring system to display a warning. The ECM will also log anevent that requires a factory password to clear.

The oil level switch (3) monitors the oil level in the pan.

The C32 engine in the 777F Truck can be equipped with an optional Oil Renewal System(ORS). The ORS increases the oil change interval and decreases the amount of used oil in needof disposal. The life of the engine is not shortened and the availability of the machine isincreased.

The ORS meters engine oil that has been filtered into the fuel supply. The metered oil isconsumed in the engine during the normal combustion process. The Engine ECM controls theamount of oil that is metered based on the actual load factor or on the fuel that is consumed bythe engine.

Whenever the old oil from the oil pan is injected into the return fuel line, new oil from amakeup tank is added to the oil pan. Regular additions of new oil will allow the oil changelevel to be extended. Reviewing the reports of the S•O•S Oil Analysis will determine if aproblem has occurred and if the oil needs to be changed.

79

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The cam speed/timing sensor (arrow) is located on the right side of the engine in the rear of thetiming gear housing behind the primary fuel filter. The cam sensor is used as a back-up for thecrank speed/timing sensor. If the crank speed/timing sensor fails, the cam speed/timing sensorallows for continuous operation.

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81

The engine will start and run when only one sensor signal is present from either the crank orcam sensor. During engine operation, if both speed/timing sensors fail, the Engine ECM willstop fuel injection and the engine will shut down. During start-up, the loss of both sensors willprevent the engine from starting.

If the engine is running and the signal from the crank speed/timing sensor is lost, a slightchange in engine performance will be noticed when the Engine ECM performs the changeoverto the cam speed/timing sensor. If the signal from the crank speed/timing sensor is not presentduring start up, the engine will start normally.

Loss of the cam speed/timing sensor during engine operation will not result in any noticeablechange in engine performance. However, if the signal from the cam speed/timing sensor is notpresent during start up, the engine may require a slightly longer period of time to start and mayrun rough for a few seconds until the ECM determines the proper firing order by using only thecrank engine speed/timing sensor.

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The teeth configuration in the crankshaft timing wheel are not the same as the camshaft timingwheel. The camshaft timing wheel includes 37 timing teeth with 36 of the teeth spaced equallyat 10° apart. One tooth is spaced 5° apart from the other teeth.

There are only 35 teeth on the crankshaft gear spaced equally at 10° apart. Two of the teeth arespaced at 20° apart, which creates a "gap" in the gear teeth.

When the Engine ECM uses the cam speed sensor to determine timing for engine starting, theECM knows exactly what cylinder is at TDC. The following cylinders are at TDC at the sametime (one cylinder bank only):

- Cylinder No. 1 (compression stroke) and No. 6 (exhaust stroke)

- Cylinder No. 2 (compression stroke) and No. 5 (exhaust stroke)

- Cylinder No. 3 (compression stroke) and No. 4 (exhaust stroke)

When the Engine ECM uses the crank speed sensor to determine timing for engine starting, theECM does not know which of the two cylinders is at TDC. As an example, the Engine ECMwill attempt to fire Cylinder No. 1 and check if there is any increase in the engine RPM. Ifthere is no increase in rpm, the ECM determines that the TDC timing position at that firingmoment is Cylinder No. 6. This action may result in a longer engine start time.

SERV1828 - 90 - Text Reference01/07

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Located behind the right pedal, the throttle position sensor (arrow) provides the desired throttleposition to the Engine ECM. If the Engine ECM detects a fault in the throttle position sensor,the throttle back-up switch in the cab can be used to increase the engine speed to 1300 rpm.

The throttle position sensor receives a regulated 8.0 ± 0.5 Volts from the Engine ECM. Thethrottle position sensor output signal is a Pulse Width Modulated (PWM) signal that varies withthrottle position and is expressed as a percentage between 0 and 100%.

To check the output signal of the throttle position sensor, connect a multimeter between Pins Band C of the throttle position sensor connector. Set the meter to read "Duty Cycle." The dutycycle output of the throttle position sensor should be:

- Low Idle: 16 ± 6%

- High Idle: 85 ± 4%

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The pre-lubrication (QuickEvac) pump (1) is located on the end of the secondary steering/brakerelease pump and motor assembly (2). The pump and motor assembly is now located on thefront of the front frame crossmember.

The engine oil pre-lubrication QuickEvac pump is controlled by the Transmission/ChassisECM. The Transmission/Chassis ECM energizes the pre-lubrication pump relay located behindthe cab. The relay behind the cab then energizes the pre-lube relay on the left frame.

The QuickEvac mode is used to allow the technician to quickly evacuate the oil for an oilchange. The QuickEvac mode can only be performed when the engine lockout is activated.

Engine starting and pre-lubrication functions are also inhibited when the engine lockout isactivated.

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If the truck is equipped with an ether start system, the Engine ECM will automatically injectether from the ether valve (arrow) and ether cylinder during cranking. The amount of automaticether injection depends on the engine oil or jacket water coolant temperature. The Engine ECMsends a duty cycle signal to the ether injection relay. The maximum duty cycle is 50%. A 50%duty cycle will pulse the ether relay ON three seconds and OFF three seconds. The maximumether delivery is ten 3-second shots per minute. Each shot delivers 6 ml (0.2 oz) of ether.

The Engine ECM will energize the ether injection relay only if:

- Engine intake manifold air temperature is below a certain temperature.- Engine coolant temperature is below a certain temperature.

Cat ET can be connected to the machine to turn the ether injection system ON or OFF.

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85

Engine Derates

The coolant temperature sensor measures the temperature of the coolant.

When the temperature of the coolant exceeds 110° C (230° F), the Engine ECM will initiate aLevel 1 Warning.

When the temperature of the coolant exceeds 111° C (231° F), the Engine ECM will initiate aLevel 2 Warning. At 111° C (231° F) the Engine ECM will initiate a 25% derate. Refer to theillustration for the remainder of the high engine coolant temperature derates. At 100% derate,the engine available power will be approximately 50%.

SERV1828 - 94 - Text Reference01/07

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Page 95: Serv1828 Txt

86

The intake manifold air temperature sensor measures the temperature of the air that is flowingto the intake manifold. The sensor is used to initiate warning levels and engine derates.

After the engine is running for at least 3 minutes and if the intake manifold air temperature goesabove 82° C (180° F), the Engine ECM will initiate a Level 1 Warning.

After the engine is running for at least 3 minutes and if the intake manifold air temperature goesabove 86° C (187° F), the Engine ECM will initiate a Level 2 Warning. With the Level 2Warning, the Engine ECM signals the engine to initiate a 3% derate. This derate will have a20% upper limit.

SERV1828 - 95 - Text Reference01/07

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Page 96: Serv1828 Txt

87

The exhaust temperature sensors measure the temperature of the exhaust air flowing out of theexhaust manifolds. The sensors are used to initiate warning levels and engine derates.

After the engine is running for over 4 minutes and if the exhaust manifold air temperature goesabove 760° C (1400° F), the Engine ECM will initiate a Level 1 Warning.

After the engine is running for over 4 minutes and if the exhaust manifold air temperature goesabove 805° C (1481° F), the Engine ECM will initiate a Level 2 Warning. With the Level 2Warning, the Engine ECM signals the engine to initiate a derate. This derate will have a 75%upper limit.

SERV1828 - 96 - Text Reference01/07

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Page 97: Serv1828 Txt

88

This illustration shows a graph with the two different warning levels for low oil pressure andthe low oil pressure derate.

When the oil pressure is below the blue line (154 kPa @ 1600 rpm) (22 psi @ 1600 rpm), theEngine ECM will enable the low oil pressure Level 1 Warning. Change machine operation orperform maintenance to the system in the event of a warning.

When the oil pressure is below the red line (104 kPa @ 1600 rpm)(15 psi @ 1600 rpm), theEngine ECM will enable the low oil pressure Level 3 Warning. The operator shouldimmediately perform a safe engine shutdown in the event of a Level 3 warning.

Also, with the Level 3 Warning the Engine ECM initiates a 35% engine derate.

If the signal between the Engine ECM and the oil pressure sensor is lost or disabled, the EngineECM will initiate a low engine oil pressure Level 1 Warning.

SERV1828 - 97 - Text Reference01/07

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Page 98: Serv1828 Txt

89

The air inlet restriction is the pressure difference between the turbo inlet pressure sensor and theatmospheric sensor. The turbo inlet pressure sensor measures the air inlet pressure at theturbocharger compressor housing.

As the air restriction increases, the pressure difference will increase. If the engine has beenrunning for over 4 minutes and the air inlet restriction is 7.5 kPa (30 in. of water) for 30seconds, the Engine ECM will initiate a Level 1 Warning. If the air restriction increases to 9.0 kPa (36 in. of water) for 30 seconds or the turbo inlet pressure sensor fails, then a Level 2Warning will occur and the engine will enter the air inlet restriction derate.

When the pressure difference between the turbo inlet pressure sensor and the atmosphericsensor reach a difference of 10.0 kPa (40 in. of water), the Engine ECM will derate the engineapproximately 2%. The Engine ECM will then derate the engine 2% more for every 1 kPa (2 in. of water) difference up to 20%.

SERV1828 - 98 - Text Reference01/07

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Page 99: Serv1828 Txt

90

This illustration shows the graph for the warning and the derates map for the fuel temperature.When the fuel temperature exceeds 90° C (194° F), the Engine ECM will activate a Level 1Warning. When the fuel temperature increases to 91.0° (196° F) a Level 2 Warning will beinitiated by the Engine ECM. At the same time, the engine will derate to 12.5%. If the fueltemperature exceeds 92° C (198° F), the engine will be derated to 25%.

A fuel temperature sensor open circuit will derate the engine to 12.5%.

Excessive fuel temperature will cause injector wear.

SERV1828 - 99 - Text Reference01/07

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Page 100: Serv1828 Txt

91

When the differential pressure switch recognizes a fuel pressure of 138 kPa (20 psi) for 1 hour,the Engine ECM will initiate a Level 1 Warning.

When the differential pressure switch recognizes 138 kPa (20 psi) across the filter for 4 hours,the Engine ECM will initiate a Level 2 Warning. With the Level 2 Warning initiated, a 35 %derate is applied to the engine.

This feature will be disabled when the fuel temperature is below 30° C (86° F).

SERV1828 - 100 - Text Reference01/07

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Page 101: Serv1828 Txt

Engine Compression Brake

The 777F Truck can be equipped with the optional engine compression brake. Thecompression brake provides higher downhill travel speeds and reduces brake wear in additionto the Automatic Retarder Control (ARC) system. The compression brake uses a master/slavehydraulic actuation system to open exhaust valves on the compression stroke which releasespressurized air and creates a net braking force at the flywheel.

The compression brake assembly, as shown in this illustration, controls two cylinders. Thecompression brake assembly is mounted to the rocker arm shaft supports below the enginevalve covers. The compression brake is pressurized with engine oil from the rocker arm shaftand uses a solenoid valve to control oil flow in the brake housing.

The compression brake is activated by a signal from the Engine ECM to the solenoid valve (1).As the fuel injector rocker arm pushes up on the master piston (2), the corresponding slavepiston (3) is pressurized to push down on the exhaust valve bridge, decompressing the cylinderand preventing the normal power stroke.

On the C32 engine, up to six brake assemblies are used. The control circuit for thecompression brake permits the operation of either two, four, or all six of the compression brakeassemblies which provides progressive braking capabilities with the retarding effect of four, six,or all 12 of the engine cylinders.

Compression brake system service consists of only periodic valve lash checks.

92

SERV1828 - 101 - Text Reference01/07

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Page 102: Serv1828 Txt

93

This illustration shows the oil flow in the C32 engine compression brake. Oil from the engineoil pump flows through the rocker arm shaft oil passage. The compression brake solenoidvalve controls the oil flow in the compression brake hydraulic circuit.

When the Engine ECM energizes the solenoid, oil flows through the check valves to the slavepistons and the master pistons.

Oil pressure overcomes spring force and the master piston moves down and contacts the fuelinjector rocker arm. The master piston will follow the movement of the fuel injector rockerarm. As the fuel injector rocker arm moves up the master piston moves up and causes the oil toclose the check valve.

With the check valve closed, oil pressure increases in the compression brake hydraulic circuitand the slave piston is forced down. The slave piston makes contact with the exhaust valverocker arm and causes the exhaust valve to open. As the exhaust valve opens, the enginecylinder pressure is relieved through the open exhaust valve, which creates a net braking forceat the flywheel.

SERV1828 - 102 - Text Reference01/07

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Page 103: Serv1828 Txt

When the fuel injector rocker arm moves down, the master piston moves down and thehydraulic pressure decreases. The exhaust valves are returned to the closed position by theexhaust rocker arm. The check valve opens and relieves the oil pressure.

When the Engine ECM de-energizes the compression brake solenoid, oil is drained from theslave and master pistons to the tank. The exhaust valves close and the slave piston returns tothe starting position.

SERV1828 - 103 - Text Reference01/07

Page 104: Serv1828 Txt

94

This illustration shows the wiring and components of the engine compression brake.

When the compression brake switch in the cab is activated, the Brake ECM sends a signal tothe Engine ECM via the Cat Data Link. The Engine ECM controls the compression brakesolenoids to slow the machine.

The Engine ECM provides three levels of braking: LOW, MEDIUM, and HIGH.

When the ECM commands a LOW braking level, two solenoids (one on each valve bank) willactivate the compression brake for four cylinders (5, 7, 6, and 8).

When the ECM commands a MEDIUM braking level, four solenoids (two on each valve bank)will activate the compression brake for eight cylinders (5, 7, 6, 8, 9, 11, 2, and 4).

When the ECM commands a HIGH braking level, six solenoids (three on each valve bank) willactivate the compression brake for all 12 cylinders.

SERV1828 - 104 - Text Reference01/07

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Page 105: Serv1828 Txt

95

This chart shows an example of the ARC and engine compression brake levels in a one minuteperiod during a drive cycle.

When the machine speed exceeds a pre-determined speed, the ARC system is activated to slowthe machine. If further braking is required, the Engine ECM will command the enginecompression brake to the LOW, MEDIUM, or HIGH brake level setting as necessary to slowthe machine.

SERV1828 - 105 - Text Reference01/07

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Page 106: Serv1828 Txt

Cooling System

The jacket water cooling system on the 777F uses a Next Generation Modular Radiator(NGMR). The NGMR (1) is a single-pass flow design, replacing the two-pass flow folded coresystem.

The coolant enters at the top left and flows out at the bottom right, similar to an automotivedesign. Being modular, individual cores may be removed for service while the radiator remainsin place.

The aftercooler cooling system in the 777F Trucks is now an ATAAC system. The ATAACcores (2) are located in front of the radiator. Intake air is cooled after being compressed by theturbocharger before being routed to the engine combustion chamber.

Also visible in this illustration is the air conditioning condenser (3).

96

SERV1828 - 106 - Text Reference01/07

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Page 107: Serv1828 Txt

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Jacket water coolant flows from the water pump (1) through the engine oil cooler (2), throughthe two brake oil coolers (3), and the transmission oil cooler (4) to both sides of the enginecylinder block. Coolant flows through the engine block to the cylinder heads. From thecylinder heads, the coolant flows to the two temperature regulators and, based on coolanttemperature, either flows to the radiator (if hot) or through the bypass tube (5) to the waterpump (if cold) to recirculate until the engine reaches operating temperature.

The thermostats are located in the thermostat housing (6) at the top of the bypass tube.

The bottom illustration shows a schematic of the coolant flow.

97

98

SERV1828 - 107 - Text Reference01/07

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Page 108: Serv1828 Txt

99

Lubrication System

The engine oil pump draws oil from the oil pan through a screen.

Oil flows from the pump through an engine oil cooler bypass valve to the engine oil cooler.The bypass valve for the engine oil cooler permits oil flow to the system during cold startswhen the oil is thick or if the cooler is plugged.

Oil flows from the engine oil cooler to the oil filters. The oil flows through the filters andenters the engine cylinder block to clean, cool, and lubricate the internal components and theturbochargers.

SERV1828 - 108 - Text Reference01/07

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Page 109: Serv1828 Txt

Fuel System

The fuel tank is located on the right side of the truck. Fuel is pulled from the tank through theprimary fuel filter by the fuel transfer pump.

Priming is now done electrically using a switch (arrow) located above the primary fuel filter. Areusable fuel/water separator mounts directly to the bottom of the fuel filter.

100

SERV1828 - 109 - Text Reference01/07

Page 110: Serv1828 Txt

The fuel transfer pump (arrow) is located at the top rear of the engine. The fuel transfer pumpcontains a bypass valve to protect the fuel system components from excessive pressure. Thebypass valve setting is higher than the setting of the fuel pressure regulator. Fuel flows fromthe transfer pump to the secondary fuel filter located on the right side of the engine.

101

SERV1828 - 110 - Text Reference01/07

Page 111: Serv1828 Txt

The differential fuel pressure switch (1) is located in the top of the secondary fuel filter housingon the right side of the engine. This switch will indicate a restriction in the fuel filter. Awarning will be sent by the Engine ECM to the monitoring system.

The fuel pressure sensor (2) is located in the top of the secondary fuel filter housing, directlybehind the differential pressure switch. This sensor is used to monitor fuel pressure.

The engine fuel temperature sensor (3) is located in the top of the secondary fuel filter housing,behind the other two sensors. The Engine ECM uses the fuel temperature measurement tomake corrections to the fuel rate and maintain power regardless of fuel temperature (withincertain parameters). This feature is called "Fuel Temperature Compensation."

102

SERV1828 - 111 - Text Reference01/07

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Fuel flows from the fuel filter base through the steel tubes (1) to the MEUI fuel injectors.Return fuel from the injectors flows through the fuel pressure regulator (2) before returning tothe fuel tank. Fuel pressure is controlled by the fuel pressure regulator.

Fuel pressure should be between 420 and 840 kPa (61 and 122 psi) at Full Load rpm.

103

SERV1828 - 112 - Text Reference01/07

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104

Fuel is pulled from the tank through the primary fuel filter by the fuel transfer pump. Fuelflows from the transfer pump to the secondary fuel filter.

Fuel flows from the secondary fuel filter base through the fuel injectors in the cylinder heads.Return fuel from the injectors flows through the fuel pressure regulator before returning to thetank.

The electric fuel priming pump is used to fill the filters after they are changed.

SERV1828 - 113 - Text Reference01/07

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Page 114: Serv1828 Txt

105

When an injector is replaced, the injector trim codes must be retrieved and installed in theEngine ECM. The trim code files are located on a CD that comes with the new injector or canbe obtained from the Service Information System (SIS).

Access the trim code files from the Cat ET Service menu as shown in the illustration.

SERV1828 - 114 - Text Reference01/07

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106

Select the injector trim file from either the CD or from the appropriate directory on thecomputer if the trim file was obtained from SIS.

SERV1828 - 115 - Text Reference01/07

Page 116: Serv1828 Txt

Air Intake and Exhaust System

Shown are the air intake system components. Check the air filter restriction indicator (1). Ifthe yellow piston is in the red zone, the air filters are restricted and must be serviced.

The air filter housing covers serve as the precleaner assemblies. When servicing the filterelements, clean the precleaners (2) and dust valves (3) using air or water pressure, or detergentwash.

The dust valve is OPEN when the engine is OFF and closes when the engine is running. Thedust valve must be flexible and closed when the engine is running or the precleaner will notfunction properly and the air filters will have a shortened life.

Two filter elements are installed in the filter housings. The large element is the primaryelement and the small element is the secondary element.

Air intake system tips:

- The primary element can be cleaned a maximum of six times.

- Never clean the secondary element for reuse. Always replace the secondary element.

- Air filter restriction causes black exhaust smoke and low power.

107

SERV1828 - 116 - Text Reference01/07

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There is a turbocharger inlet pressure sensor (arrow) located in the tube between the air filtersand the turbochargers. This illustration shows one of the inlet pressure sensors. The EngineECM uses the turbocharger inlet pressure sensor in combination with the atmospheric pressuresensor to determine air filter restriction. The ECM provides the input signal to the monitoringsystem, which informs the operator of the air filter restriction.

As the air restriction increases, the pressure difference will increase. If the engine has beenrunning for over 4 minutes and the air inlet restriction is 7.5 kPa (30 in. of water) for 30seconds, the Engine ECM will initiate a Level 1 Warning. If the air restriction increases to 9.0 kPa (36 in. of water) for 30 seconds or the turbo inlet pressure sensor fails, then a Level 2Warning will occur and the engine will enter the air inlet restriction derate.

When the pressure difference between the turbo inlet pressure sensor and the atmosphericsensor reach a difference of 10.0 kPa (40 in. of water), the Engine ECM will derate the engineapproximately 2%. The Engine ECM will then derate the engine 2% more for every 1 kPa (2in. of water) difference up to 20%.

108

SERV1828 - 117 - Text Reference01/07

Page 118: Serv1828 Txt

The C32 engine is equipped with two turbochargers, one on each side. Each turbocharger isdriven by the exhaust gas from the cylinders which enters the turbine side (1) of theturbocharger from the exhaust manifold. The exhaust gas flows through the turbocharger,spinning the turbine wheel, then exits to the exhaust piping and muffler.

The clean air from the filters enters the compressor side (2) of the turbocharger where it iscompressed by the spinning turbine and picks up heat. The compressed air from theturbocharger then flows out the top of the turbocharger to the aftercooler. After the air is cooledby the aftercooler, the air flows to the cylinders and combines with the fuel for combustion.

109

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12

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The compressed air that was heated at the turbochargers is routed through finned Air to AirAfterCooler (ATAAC) cores (arrows) mounted in front of the radiator. Outside air passesthrough the ATAAC cores and the radiator to cool both the intake air and the engine coolant.The cooled, compressed air exits the aftercoolers and is piped to the intake manifolds.

110

SERV1828 - 119 - Text Reference01/07

Page 120: Serv1828 Txt

Two exhaust temperature sensors (arrows) are located in each exhaust manifold. The exhausttemperature sensors send a signal to the Engine ECM indicating exhaust temperature.

When the engine runs at low idle, the temperature of an exhaust manifold port can indicate thecondition of a fuel injection nozzle. A low temperature indicates that no fuel is flowing to thecylinder. An inoperative fuel injection nozzle or a problem with the fuel injection pump couldcause this low temperature.

A very high temperature can indicate that too much fuel is flowing to the cylinder. Amalfunctioning fuel injection nozzle, plugged air filters, or a restriction in the turbochargers orthe muffler could cause this very high temperature.

111

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Page 121: Serv1828 Txt

Shown are the turbocharger outlet pressure sensors (1). The turbocharger outlet pressuresensors send an input signal to the Engine ECM. The Engine ECM compares the value of theturbo outlet pressure sensor with the value of the atmospheric pressure sensor (2) and calculatesboost pressure.

The best way to check for a power problem is to compare the truck performance with therimpull charts in the Caterpillar Performance Handbook or the 777F Specalog. The truckshould be able to climb a grade in the same gear as specified in these two publications.

If an engine power problem is suspected, check boost pressure at full load rpm. If boostpressure is correct at full load rpm, the engine is not the problem and other systems such as thetorque converter should be checked.

To check boost pressure at full load rpm, the truck must be operated in FIRST GEAR with thethrottle at MAXIMUM and the retarder gradually engaged. Traveling up a grade is best as longas the engine rpm does not fall below the full load rpm specification during the test. Graduallyengage the retarder until the full load rpm is displayed. When the full load rpm is displayed,record the boost pressure. If boost pressure is within the specifications at full load rpm, theengine is operating correctly.

NOTE: The monitoring system includes a transmission stall test that can be used tocheck boost at full load. Cat ET should be used to view the status while running thetransmission stall test.

112

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12

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Use Cat ET or the monitoring system display panel to view the engine rpm and boost pressure.

Generally, Torque Converter (TC) stall speed (in gear, full throttle, zero ground speed) is usedto determine if the engine power is low or a torque converter problem exists. For example, ifthe engine power is within specification and the stall speed is high, the torque converter mayhave a problem (low internal oil pressure, poor internal tolerances or damaged components).

NOTE: The 777F has a torque limiting function and engine speed is always limited to1831 rpm during the stall test.

SERV1828 - 122 - Text Reference01/07

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This schematic shows the flow through the air induction and exhaust system.

The turbochargers are driven by the exhaust gas from the cylinders which enters the turbineside of the turbochargers. The exhaust gas flows through the turbochargers, the exhaust piping,and the mufflers.

The clean air from the filters enters the compressor side of the turbochargers. The compressedair from the turbochargers flows to the ATAAC. After the air is cooled by the ATAAC, the airflows to the cylinders and combines with the fuel for combustion.

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Page 124: Serv1828 Txt

114

POWER TRAIN

The 777F Off-highway Truck power train is electronically controlled. TheTransmission/Chassis ECM controls the ECPC transmission shifting and the torque converterlockup clutch operation. The transmission has seven forward speeds and one reverse speed.

Power flows from the engine to the rear wheels through the power train. The main power traincomponents are:

- Torque converter (1)

- Drive shaft (2)

- Transfer gears (3)

- Transmission (4)

- Differential (5)

- Final drives (6)

Other power train components visible in this illustration are the transmission charge filters (7),torque converter charging filter (8), and two-section hydraulic tank (9).

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These illustrations show the location of the main electronic components in the power train. TheTransmission/Chassis ECM (1) is located behind the cab seat and is accessed by removing apanel at the rear of the cab. The transmission modulating valves (2) are located on top of thetransmission planetary gears and are accessed by removing a cover plate. The torque converterlockup clutch solenoid valve (3) is located on the rear of the torque converter.

NOTE: The Transmission/Chassis ECM receives input signals from severalcomponents located on the machine to control transmission shifting and the torqueconverter lockup clutch operation. The electronic components will be covered later inthe presentation.

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116

Shown is the transmission and torque converter hydraulic system for the 777F. A five sectionpump is located at the rear of the torque converter housing. The first section (attached to pumpdrive at rear of torque converter) scavenges oil from the bottom of the torque converter caseand returns the oil to the hoist, torque converter, and brake hydraulic tank. The second sectionpumps charge oil through the torque converter filter to the torque converter. The third sectionsends oil through the lockup clutch filter and provides pilot oil to the following circuits:

- Lockup clutch valve

- Variable speed fan clutch control

- Hoist pilot signal resolver

- Traction control valve

The fourth section scavenges oil from the transmission sump and sends oil to the transmissionoil cooler and the transmission hydraulic tank.

The fifth section sends charge oil through the transmission oil filters to the transmission controlvalves.

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117

Torque Converter Hydraulic System

This schematic shows the oil flow from the torque converter pump through the torque converterhydraulic system.

The scavenge pump section pulls oil through a screen from the torque converter housing andsends the oil to the hoist, torque converter, and brake hydraulic tank.

The torque converter charging pump section sends oil through the torque converter chargingfilter to the torque converter inlet relief valve. Oil flows from the inlet relief valve through thetorque converter to the outlet relief valve. Oil flows from the outlet relief valve to the brake oilcooling circuit.

The lockup clutch valve pump section sends oil through the lockup clutch valve filter to thetorque converter lockup clutch valve. When oil pressure in the lockup clutch valve circuit istoo high, the lockup clutch relief valve allows oil to flow to the brake cooling circuit.

Oil from the lockup clutch valve pump section also flows to the TCS valve, variable speedclutch control and hoist pilot signal resolver.

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The five sections of the power train pump (from the front to the rear) are:

- Torque converter scavenge (1)

- Torque converter charging (2)

- Lockup clutch valve, hoist pilot circuit, TCS valve, and variable speed fan clutch (3)

- Transmission scavenge (4)

- Transmission charging (5)

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SERV1828 - 128 - Text Reference01/07

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In DIRECT DRIVE, the lockup clutch is engaged by hydraulic pressure and locks the turbine tothe impeller. The housing, impeller, turbine, and output shaft then rotate as a unit at enginerpm. The stator, which is mounted on a one-way clutch, is driven by the force of the oil in thehousing. The one-way clutch permits the stator to turn freely in DIRECT DRIVE when torquemultiplication is not required.

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This sectional view shows a torque converter in CONVERTER DRIVE. The lockup clutch(yellow piston and blue discs) is not engaged. During operation, the rotating housing andimpeller (red) can rotate faster than the turbine (blue). The stator (green) remains stationaryand multiplies the torque transfer between the impeller and the turbine. The output shaft rotatesslower than the engine crankshaft, but with increased torque.

Page 130: Serv1828 Txt

The five section power train pump (1) is located at the bottom rear of the torque converter.

The inlet relief valve (2) limits the maximum pressure of the supply oil to the torque converter.The torque converter inlet relief pressure can be checked by removing a plug and installing apressure tap. Normally, the inlet relief pressure will be slightly higher than the outlet reliefvalve pressure.

Oil flows through the inlet relief valve and enters the torque converter. Some of the oil willleak through the torque converter to the bottom of the housing to be scavenged. Most of the oilin the torque converter is used to provide a fluid coupling and flows through the torqueconverter outlet relief valve (3).

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The outlet relief valve maintains the minimum pressure inside the torque converter. The mainfunction of the outlet relief valve is to keep the torque converter full of oil to preventcavitation. The outlet relief pressure can be measured at the tap (4) on the outlet relief valve.

The torque converter lockup clutch valve (5) directs oil to engage the torque converter lockupclutch. The torque converter lockup clutch pressure can be checked at the tap (6) on top of thelockup clutch valve.

Excess oil that accumulates in the bottom of the torque converter is scavenged by the firstsection of the pump through a screen behind the access cover (7) and returned to the hoist,torque converter, and brake hydraulic tank.

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123

The torque converter lockup clutch modulating valve contains a proportional solenoid thatreceives a signal from the Transmission/Chassis ECM to engage and release the torqueconverter lockup clutch.

In this illustration, the lockup clutch modulating valve is shown with no current signal appliedto the solenoid (TORQUE CONVERTER DRIVE or NEUTRAL). The Transmission/ChassisECM controls the rate of oil flow through the lockup clutch modulating valve to the lockupclutch by changing the signal current strength to the solenoid. With no current signal applied tothe solenoid, the transmission modulating valve is DE-ENERGIZED and oil flow to the clutchis blocked.

Pump oil flows into the valve body around the valve spool and into a drilled passage in thecenter of the valve spool. The oil flows through the drilled passage and orifice to the left sideof the valve spool to a drain orifice. Since there is no force acting on the pin assembly to holdthe ball against the drain orifice, the oil flows through the spool and the drain orifice past theball to the tank.

The spring located on the right side of the spool in this view holds the valve spool to the left.The valve spool opens the passage between the clutch passage and the tank passage and blocksthe passage between the clutch passage and the pump supply port. Oil flow to the clutch isblocked. Oil from the clutch drains to the tank preventing clutch engagement.

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124

In this illustration, the modulating valve is shown with a maximum current signal commandedto the solenoid. When the modulation cycle stops, the Transmission/Chassis ECM sends themaximum specified current signal to fully engage the lockup clutch (DIRECT DRIVE).

The constant current signal pushes the pin firmly against the ball in the solenoid valve. The pinforce against the ball blocks more oil from flowing through the drain orifice. This restrictioncauses an increase in pressure on the left side of the valve spool. The valve spool moves to theright to allow pump flow to fully engage the clutch.

In a short period of time, maximum pressure is felt at both ends of the proportional solenoidvalve spool. This pressure along with the spring force on the right end of the spool cause thevalve spool to move to the left until the forces on the right end and the left end of the valvespool are balanced.

The valve spool movement to the left (balanced) position reduces the flow of oil to the engagedclutch. The Transmission/Chassis ECM sends a constant maximum specified current signal tothe solenoid to maintain the desired clutch pressure.

NOTE: The lockup clutch valve is calibrated with Cat ET.

SERV1828 - 133 - Text Reference01/07

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Page 134: Serv1828 Txt

A torque converter outlet temperature sensor (arrow) provides an input signal to theTransmission/Chassis ECM, which sends a signal to the monitoring system to inform theoperator of the torque converter outlet temperature.

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The filter has a bypass switch (3) which provides an input signal to the monitoring system, viathe Transmission/Chassis ECM, to inform the operator if the filter is restricted. The filterhousing has an S•O•S tap (4) and a lockup clutch circuit pressure tap (5).

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Oil from the lockup clutch valve pump section flows to the lockup valve oil filter (1) and thento the lockup clutch modulating valve (2). The filter is located inside of the left frame rail.

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The lockup clutch relief valve (1) is located inside the left frame rail in front of the lockupclutch filter (2). This view is looking up from the bottom of the truck. When oil pressure inthe lockup clutch valve circuit is too high, the lockup clutch relief valve allows oil to flow tothe brake cooling circuit.

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The torque converter filter includes an S•O•S port (2) located on the bottom of the filter.

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The torque converter charging filter (1) is located on the right frame rail, behind the right fronttire. Oil from the torque converter charging pump section flows through the torque converterfilter to the torque converter inlet relief valve.

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131

Transmission Hydraulic System

The transmission scavenge pump section pulls oil from the bottom of the transmission casethrough a magnetic screen and sends the oil through the transmission oil cooler to thetransmission tank. The magnetic screen should always be checked for debris if a problem withthe transmission is suspected.

The transmission charging pump section pulls oil from the transmission hydraulic tank.Charging oil flows from the pump through two transmission charging filters to the transmissionmain relief valve and seven modulating valves.

The main relief valve regulates the supply pressure inside the transmission hydraulic system.Oil unseats the check ball and forces the spool to the right if the transmission system pressurebecomes greater than the spring force on the right of the spool. Excess oil will flow to thelubrication circuit and the lube relief valve. The lubrication circuit oil and oil from the luberelief valve flows to the transmission sump. The relief valve is adjustable by turning theadjusting screw on the right end of the valve.

SERV1828 - 138 - Text Reference01/07

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The clutch modulating valves control the engagement of the transmission clutches. Thesolenoids are controlled by a pulse width modulated (PWM) signal from theTransmission/Chassis ECM. Supply oil flows into the clutch modulating valves and through apassage in the center of the spool. Oil then flows to the tank if the solenoid is not energized.Oil flow is blocked by a ball and seat if the solenoid is energized. The spool will shift downand the clutch will begin to fill. The signal from the Transmission/Chassis ECM determineshow long it takes to fill each clutch.

The transmission lubrication relief valve limits the transmission lubrication oil pressure.

SERV1828 - 139 - Text Reference01/07

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The transmission scavenge pump section (1) pulls oil from the bottom of the transmission casethrough a magnetic screen and sends the oil through the transmission oil cooler (2) to thetransmission tank. The oil cooler is located on the right side of the engine.

The transmission charging pump section (3) pulls oil from the bottom of the transmissionhydraulic tank through a magnetic screen and sends the oil through the transmission filters tothe transmission hydraulic controls.

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Oil from the transmission charging pump section is sent to the transmission charge oil filters (1) located on the cross member on the right side of the machine.

The rear filter housing has an S•O•S tap (2) and a charge pressure tap (3). The rear filterhousing also has a bypass switch (4) which provides an input signal to the monitoring system,via the Transmission/Chassis ECM, to inform the operator if the filter is restricted.

The ECPC transmission hydraulic controls can be accessed by removing a cover plate (5) ontop of the transmission. The transmission input speed sensor (6) is located on top of thetransfer gear housing. The transmission input speed sensor sends an input to theTransmission/Chassis ECM which checks the speed of the drive shaft to the speed of theengine.

The transmission has pressure taps located on the outside of the transmission which aids inpreventing contamination from entering the transmission as well as saving time when checkingthe pressures on the 777F transmission.

Shown in the lower right illustration are the transmission control valve pressure taps. Theconverter inlet pressure tap (7) and the transmission hydraulic system pressure tap (8) arelocated toward the rear of the transmission. Oil pressure for the seven clutches can be checkedat the remaining seven taps (9) on the transmission.

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135

The transmission modulating valves control the oil to corresponding transmission clutches. Thesolenoid valves are:

- Clutch No. 1 Solenoid valve (1)- Clutch No. 2 Solenoid valve (2)- Clutch No. 3 Solenoid valve (3)- Clutch No. 4 Solenoid valve (4)- Clutch No. 5 Solenoid valve (5)- Clutch No. 6 Solenoid valve (6)- Clutch No. 7 Solenoid valve (7)

The main relief valve (8) controls the transmission hydraulic pressure, and the lubrication reliefvalve (not visible) controls the lubrication pressure. The lubrication relief valve is locatedbelow the main relief valve.

Also located on the transmission hydraulic control valve is the transmission hydraulic oiltemperature sensor (9). The temperature sensor sends a signal to the Transmission/ChassisECM indicating transmission oil temperature.

SERV1828 - 142 - Text Reference01/07

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The table in this illustration lists the solenoids that are energized and clutches that are engagedfor each transmission speed. This table can be useful for transmission diagnosis.

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In this illustration, the transmission modulating valve is shown with no current signal applied tothe solenoid. The Transmission/Chassis ECM controls the rate of oil flow through thetransmission modulating valves to the clutches by changing the signal current strength to thesolenoid. With no current signal applied to the solenoid, the transmission modulating valve isDE-ENERGIZED and oil flow to the clutch is blocked.

Pump oil flows into the valve body around the valve spool and into a drilled passage in thecenter of the valve spool. The oil flows through the drilled passage and orifice to the left sideof the valve spool to a drain orifice. Since there is no force acting on the pin assembly to holdthe ball against the drain orifice, the oil flows through the spool and the drain orifice past theball to the tank.

The spring located on the right side of the spool in this view holds the valve spool to the left.The valve spool opens the passage between the clutch passage and the tank passage and blocksthe passage between the clutch passage and the pump supply port. Oil flow to the clutch isblocked. Oil from the clutch drains to the tank preventing clutch engagement.

SERV1828 - 144 - Text Reference01/07

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In this illustration, the modulating valve is shown with a signal to the solenoid that is below themaximum current. Clutch engagement begins when the Transmission/Chassis ECM sends aninitial current signal to ENERGIZE the solenoid. The amount of commanded current signal isproportional to the desired pressure that is applied to the clutch during each stage of theengagement and disengagement cycle.

The start of clutch engagement begins when the current signal to the solenoid creates amagnetic field around the pin. The magnetic force moves the pin against the ball in proportionto the strength of the current signal from the Transmission/Chassis ECM.

The position of the ball against the orifice begins to block the drain passage of the oil flow fromthe left side of the valve spool to the tank. This partial restriction causes the pressure at the leftend of the valve spool to increase. The oil pressure moves the valve spool to the right againstthe spring. As the pressure on the right side of the valve spool overrides the force of the spring,the valve spool shifts to the right.

The valve spool movement starts to open a passage on the right end of the valve spool for pumpsupply oil to fill the clutch. Oil also begins to fill the spring chamber on on the right end of thespool.

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Page 146: Serv1828 Txt

In the initial clutch filling stage, the Transmission/Chassis ECM commands a high current pulseto quickly move the valve spool to start filling the clutch. During this short period of time, theclutch piston moves to remove the clearances between the clutch discs and plates to minimizethe amount of time required to fill the clutch. The ECM then reduces the current signal whichreduces the pressure setting of the proportional solenoid valve. The change in current signalreduces the flow of oil to the clutch. The point where the clutch plates and discs start to touchis called TOUCH-UP.

Once TOUCH-UP is obtained, the Transmission/Chassis ECM begins a controlled increase ofthe current signal to start the MODULATION cycle. The increase in the current signal causesthe ball and pin to further restrict oil through the drain orifice to tank causing a controlledmovement of the spool to the right. The spool movement allows the pressure in the clutch toincrease.

During the MODULATION cycle, the valve spool working with the variable commandedcurrent signal from the Transmission/Chassis ECM acts as a variable pressure reducing valve.

The sequence of partial engagement is called desired slippage. The desired slippage iscontrolled by the application program stored in the Transmission/Chassis ECM.

SERV1828 - 146 - Text Reference01/07

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139

In this illustration, the modulating valve is shown with a maximum current signal commandedto the solenoid. When the modulation cycle stops, the Transmission/Chassis ECM sends themaximum specified current signal to fully engage the clutch.

The constant current signal pushes the pin firmly against the ball in the solenoid valve. The pinforce against the ball blocks more oil from flowing through the drain orifice. This restrictioncauses an increase in pressure on the left side of the valve spool. The valve spool moves to theright to allow pump flow to fully engage the clutch.

In a short period of time, maximum pressure is felt at both ends of the proportional solenoidvalve spool. This pressure, along with the spring force on the right end of the spool, causes thevalve spool to move to the left until the forces on the right end and the left end of the valvespool are balanced.

The valve spool movement to the left (balanced) position reduces the flow of oil to the engagedclutch. The Transmission/Chassis ECM sends a constant maximum specified current signal tothe solenoid to maintain the desired clutch pressure.

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Page 148: Serv1828 Txt

The different maximum specified pressures for each clutch is caused by different maximumcurrent signals being sent by the Transmission/Chassis ECM to each individual modulatingvalve. The different maximum signal causes a difference in the force pushing the pin againstthe ball to block leakage through the drain orifice in each solenoid valve. The different rate ofleakage through the spool drain orifice provides different balance positions for the proportionalsolenoid valve spool. Changing the valve spool position changes the flow of oil to the clutchand the resulting maximum clutch pressure.

The operation of the proportional solenoid to control the engaging and releasing of clutches isnot a simple on and off cycle. The Transmission/Chassis ECM varies the strength of thecurrent signal through a programmed cycle to control movement of the valve spool.

The clutch pressures can be changed using Caterpillar Electronic Technician (ET) during thecalibration procedure.

SERV1828 - 148 - Text Reference01/07

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140

The transmission hydraulic control relief valve is used to regulate the pressure to the maincomponents in the transmission.

Oil enters the relief valve at the supply port. The pressure of the oil unseats the ball and movesthe spool toward the right. Oil flows past the spool and to the tank to regulate transmission oilpressure.

The adjustment screw alters the preload on the spring to adjust the relief pressure.

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Rear Axle

Check the differential oil level by removing the magnetic inspection plug (1). The oil shouldbe level with the bottom of the fill plug opening. The magnetic inspection plug should beremoved at regular intervals and checked for metal particles. The plug (2) at the bottom of thedifferential housing is used to drain the oil.

The optional remote grease fittings (3) are located on top of the differential.

Inspect the condition of the rear axle breather (4) at regular intervals. The breather preventspressure from building up in the axle housing. Excessive pressure in the axle housing cancause brake cooling oil to leak through the Duo-Cone seals in the wheel brake assemblies. Theparking brake oil pressure can be checked at the pressure taps (5) on top of the axle.

A differential carrier thrust pin is located behind the small cover (6). The thrust pin preventsmovement of the differential carrier during high thrust load conditions.

The backup alarm (7) is located on top of the rear frame. When the machine is in reverse, theTransmission/Chassis ECM sends a signal to sound the back-up alarm.

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Shown is the differential removed from the rear axle housing. The differential is located in therear axle housing behind the transmission. Power flows from the transmission to thedifferential. The differential divides the power to the right and left axle shafts. Torque istransmitted equally from the differential through the two axle shafts to the final drives. Thedifferential adjusts the speed of the axle shafts for vehicle cornering, therefore, the powerdelivered to the axle shafts is unequal during cornering.

The differential thrust pin contacts the differential carrier at the location shown (arrow). Whenhigh thrust loads are transmitted from the differential pinion to the differential ring gear, thecarrier tries to move away from the pinion. The thrust pin prevents movement of thedifferential carrier during high thrust load conditions.

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143

Transmission/Chassis Electronic Control System

Shown in this illustration are the transmission/chassis electronic control system inputs andoutputs for the 777F trucks.

The main purpose of the Transmission/Chassis ECM is to determine the desired transmissiongear and energize the appropriate solenoids to shift the transmission up or down as requiredbased on information from both the operator and machine. The Transmission/Chassis ECMalso controls all the hoist functions, the steering disable function, and other functions asdescribed in this presentation.

The Transmission/Chassis ECM receives information from various input components such asthe shift lever switch and the transmission output speed sensors.

Based on the input information, the Transmission/Chassis ECM determines whether thetransmission should upshift, downshift, engage the lockup clutch, or limit the transmission gear.These actions are accomplished by sending signals to various output components.

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Page 153: Serv1828 Txt

Power train output components include the transmission modulating valve solenoids and lockupclutch solenoid. Several other Transmission/Chassis ECM output components are coveredthroughout the presentation.

The Engine ECM, the monitoring system, the Transmission/Chassis ECM, and the Brake ECMall communicate with each other through the CAT Data Link. Communication between theelectronic control modules allows the sensors of each system to be shared. Many additionalbenefits are provided, such as Controlled Throttle Shifting (CTS). CTS occurs when theTransmission/Chassis ECM tells the Engine ECM to reduce or increase engine fuel during ashift to lower stress to the power train.

The Electronic Technician (ET) Service Tool can be used to perform several diagnostic andprogramming functions.

NOTE: Some of the Transmission/Chassis ECM input and output components areshown during the discussion of other systems.

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The Transmission/Chassis ECM (arrow) is located in the compartment at the rear of the cab.The Transmission/Chassis ECM performs the transmission control functions, plus some othermachine functions (hoist and secondary steering control). Because of the functionality of thecontrol, it is referred to as the Transmission/Chassis ECM.

The Transmission/Chassis ECM is an A4M1 module with two 70-pin connectors. TheTransmission/Chassis ECM communicates with the Engine ECM, Brake ECM, and monitoringsystem over the CAT Data Link and can communicate with some attachments over the CANDatalink.

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At the base of the shift lever (1) is a position sensor (2) which provides input signals to theTransmission/Chassis ECM when the operator moves the lever. The shift lever position sensoris a Hall effect position sensor. The shift lever is connected to a device which contains twomagnets. One magnet (3) is visible in the bottom left view.

As the lever is moved, the magnets pass over the Hall Cell (4) and the change in the magneticfield produces a signal. The internal electronics (5) of the sensor process the signal and send aPWM signal to the ECM.

The lever position sensor receives 24 VDC from the machine electrical system. The sensorcontains a fourth pin that is used for calibration on some machine applications.

The following measurements would be typical for the position sensor with the sensor connectedto the Transmission/Chassis ECM and the key switch turned ON:

• Pin 1 to Pin 2 -- Supply Voltage

• Pin 3 to Pin 2 -- .7 - 6.9 DCV on DC volts scale

• Pin 3 to Pin 2 -- 4.5 - 5.5 KHz on the KHz scale

• Pin 3 to Pin 2 -- 5% - 95% duty cycle on the % scale

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Also shown in the top right illustration is the drive gear UP switch (6) and the drive gearDOWN switch (7). The drive gear switches are toggle switches that send a signal to theTransmission/Chassis ECM. When the drive gear UP switch is pressed, the high gear limit canbe increased up to seventh gear. When the drive gear DOWN switch is pressed, the high gearlimit can be decreased down to third gear.

The transmission shift lever lock button (8) unlocks the transmission shift lever when pressed.

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The transmission output speed sensors are located on the transfer gear housing on the input endof the transmission behind a cover (arrow). Although the sensors are physically located nearthe input end of the transmission, the sensors are measuring the speed of the transmissionoutput shaft. The sensors are two wire passive sensors. The passive speed sensor uses thepassing teeth of the output shaft to provide a frequency signal. The signal from the sensor isused for automatic shifting of the transmission. The signal is also used to drive thespeedometer and as an input to other electronic controls.

The Transmission/Chassis ECM also performs a check between the two measured transmissionoutput speeds and the transmission input speed to ensure that the ECM calculates an accuratetransmission speed. This check also uses the speeds to determine the direction of motion of themachine.

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The engine speed sensor (arrow) is located at the rear of the engine on the left side of the gearhousing. The engine speed sensor sends a frequency signal to the Transmission/Chassis ECMindicating engine speed. The Transmission/Chassis ECM uses the engine speed signal input todetermine actual engine speed. The actual engine speed is one of the parameters used todetermine the proper transmission shift points.

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The transmission oil level switch (arrow), located near the bottom of the transmission tank,sends a signal to the Transmission/Chassis ECM indicating the hydraulic oil level in thetransmission tank.

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The body up switch (1) is located on the frame near the body pivot pin. This magnetic switchis normally open. When the body is raised, a magnet (2) mounted on the body passes theswitch and causes the switch to close. The resulting ground signal is sent to theTransmission/Chassis ECM. This signal is used to limit the top gear into which thetransmission will shift when the body is up.

The body up top gear value is programmable from FIRST to THIRD utilizing the Cat ETService Tool. The ECM comes from the factory with this value set to FIRST gear. Whendriving away from a dump site, the transmission will not shift past FIRST gear until the body isdown. If the transmission is already above the set limit gear when the body is raised, nolimiting action will take place.

The body up switch signal is also used to control the SNUB position of the hoist control valve.As the body is lowered and the magnet passes the body up switch, the Transmission/ChassisECM signals the hoist lower solenoid to move the hoist valve spool to the SNUB position. Inthe SNUB position, the body float speed is reduced to prevent the body from making hardcontact with the frame.

The body up switch input provides the following functions:

- Body up gear limiting

- Illuminates the backup lights

- Hoist snubbing

- Lights the body up dash lamp

- Signals a new load count (after 10 seconds in the RAISE position)

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A diagnostic code occurs if the Transmission/Chassis ECM does not receive a closed (ground)signal from the switch within four hours of operation time or an open signal from the switchwithin one hour of operation time. The body up switch must be adjusted properly for all of thefunctions to operate correctly.

Two LEDs are located on the body up switch. The green LED indicates that battery power ispresent. The amber LED indicates that the switch is closed (grounded).

The body position switch can be raised or lowered slightly in the bracket notches to start theSNUB feature sooner or later.

NOTE: The snub feature can also be adjusted in the Cat ET hoist configuration screenby selecting the "Hoist lower valve adjustment status."

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Besides controlling the Transmission Shifting and Torque Converter Lockup, theTransmission/Chassis ECM also controls other functions as shown above, such as ControlThrottle Shifting (CTS), Directional Shift Management, and Top Gear Limit.

There are several programmable parameters available with the Transmission/Chassis ECM.

NOTE: Refer to the Transmission/Chassis Electronic Control System Operation,Troubleshooting, Testing, and Adjusting manual (RENR8342) for more information onthe additional Transmission/Chassis ECM functions and programmable parameters.

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151

STEERING SYSTEM

The steering system on the 777F is similar to the 777D except a steering disable solenoid valvehas been added and some of the component locations have changed.

When energized, the steering disable solenoid valve stops the oil flow coming from the steeringpump. This prevents the front wheels from turning to allow servicing to be conducted safely inthe front wheel area.

The steering system uses a load sensing, pressure compensated pump. Minimal horsepower isused by the steering system when the truck is traveling in a straight path. Steering hydraulichorsepower requirements depend on the amount of steering pressure and flow required by thesteering cylinders.

This illustration shows the following main steering components:

- Steering pump (1)

- Steering disable valve andsteering valve (2)

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- HMU (3)

- Steering tank (4)

- Secondary steering pump (5)

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The steering system tank is located on the right platform

Check the steering system oil level at the sight gauge (1).

The steering system oil filter (2) is located on the side of the steering tank.

The steering system uses a pressure compensated piston type pump. Case drain oil from thesteering pump returns to the hydraulic tank through a case drain filter (3) on the side of thesteering tank.

Before removing the cap to add oil to the steering system, depress the pressure release button (4) on the breather to release any remaining pressure from the tank.

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The steering system filter base and the case drain filter base have bypass valves that allow thesteering oil to bypass the filters if they are plugged.

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The 777F Trucks are equipped with a load sensing, pressure compensated, piston-type pump.The steering pump operates only when the engine is running and provides the necessary flow ofoil for steering system operation. The steering pump contains a load sensing controller withtwo valves. The high pressure cutoff valve (1) functions as the primary steering system reliefvalve.

The flow compensator valve (2) is used to adjust the low pressure standby setting. When thetruck is traveling in a straight path, virtually no flow or pressure is sent to the steeringcylinders, and the pump destrokes to low pressure standby.

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When the truck is traveling in a straight path, the steering cylinders require virtually no flow orpressure. The HMU provides a very low pressure load sensing signal to the flow compensatorin the load sensing controller.

Pump oil (at low pressure standby) flows to the swashplate piston and past the lower end of thedisplaced flow compensator spool to the actuator piston. The actuator piston has a largersurface area than the swashplate piston. The oil pressure at the actuator piston overcomes thespring force and the oil pressure in the swashplate piston and moves the swashplate to destrokethe pump. The pump is then at minimum flow, low pressure standby.

Pump output pressure is equal to the setting of the flow compensator plus the pressure requiredto compensate for system leakage.

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During a turn, when steering pressure and flow are required, pressure increases in the HMUload sensing signal line. The pressure in the signal line is equal to the pressure in the steeringcylinders. The pump load sensing controller is spring biased to vent the actuator pistonpressure to drain. Venting pressure from the load sensing controller and the actuator pistonpositions the spring biased swashplate to maximum displacement (maximum flow).

As pressure increases in the HMU load sensing signal line, pump supply pressure is sensed onboth ends of the flow compensator. When pressure is present on both ends of the flowcompensator, the swashplate is kept at maximum angle by the force of the spring in the pumphousing and pump discharge pressure on the swashplate piston. The pistons reciprocate in andout of the barrel and maximum flow is provided through the outlet port. Since the pump isdriven by the engine, engine rpm also affects pump output.

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The steering disable valve (1) is located behind the shock on the right frame rail.

When the steering disable solenoid valve (2) is energized, oil flow from the steering pump tothe steering valve is blocked by the steering disable valve, which allows servicing behind thefront wheels with the machine running.

When the machine lockout switch, located under a panel on the left stairway, is toggled, asignal is sent to the Transmission/Chassis ECM. The Transmission/Chassis ECM energizes thesteering disable solenoid allowing service to be performed behind the front wheels safely.

Also located on the steering disable valve is a pressure tap (3) for checking the load sensingsignal to the pump, and an S•O•S tap (4).

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Steering oil flows from the pump through the steering disable valve to the steering valve (1)located on the frame behind the right front suspension cylinder. The primary steering pressureswitch (2) monitors the output of the steering pump. The steering pressure switch providesinput signals to the Transmission/Chassis ECM which sends a signal to the monitoring systemto inform the operator of the steering system condition. A steering system warning is displayedif the pressure is too low.

The steering pressure switch cannot tolerate high steering system pressures. A pressurereducing valve (not visible) reduces the steering system pressure to the steering pressure switch.

Two relief valves are located on the front of the steering valve. The secondary steering back-uprelief valve protects the secondary steering system if the relief valve on the secondary steeringpump malfunctions. The primary steering back-up relief valve protects the primary steeringsystem if the high pressure cutoff valve on the steering pump malfunctions. Primary steeringpressure is first controlled by the high pressure cutoff valve located on the steering pump.

Steering system pressures can be measured at the steering system pressure tap located on thefront of the steering valve.

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This illustration shows the location of the HMU (arrow) for the 777F. Serviceability hasimproved for the HMU on the 777F due to the redesigned walkways. The HMU is connectedto the steering wheel and controlled by the operator.

The HMU meters the amount of oil sent to the steering cylinders by the speed at which thesteering wheel is turned. The faster the HMU is turned, the higher the flow sent to the steeringcylinders, and the faster the wheels will change direction.

The steering system is referred to as "Q-amp" which means flow amplification. During asudden steering change (steering wheel speed greater than 10 rpm), additional steering pump oilflow will bypass the gerotor pump in the HMU and flow directly to the steering cylinders.Steering oil flow to the cylinders is equal to the gerotor pump oil flow plus the bypass oil flowfrom the steering pump. The steering oil flow is amplified up to 1.6 to 1. The purpose of theflow amplification is to provide quick steering response when sudden steering changes areneeded.

Two crossover relief valves are installed in the top of the HMU. The crossover relief valves areinstalled in series with the left and right turn ports. If an outside force is applied to the frontwheels while the steering wheel is stationary, the crossover relief valves provide circuitprotection for the steering lines between the steering cylinders and the HMU. The crossoverrelief valves allow oil to transfer from one end of the steering cylinders to the opposite end ofthe cylinders.

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To test the right crossover relief valve, install two tees with pressure taps in the right turnsteering hose at the steering cylinders. Steer the truck completely to the right against the stops,and shut off the engine. An external pump supply must be connected to one of the pressuretaps on the right turn hose. Connect a pressure gauge to the other pressure tap on the right turnhose. Pressurize the steering system, and the reading on the gauge will be the setting of theright crossover relief valve.

To test the left crossover relief valve, install two tees with pressure taps in the left turn steeringhose at the steering cylinders. Steer the truck completely to the left against the stops, and shutoff the engine. An external pump supply must be connected to one of the pressure taps on theleft turn hose. Connect a pressure gauge to the other pressure tap on the left turn hose.Pressurize the steering system, and the reading on the gauge will be the setting of the leftcrossover relief valve.

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The electric secondary steering pump (1) and motor (2) on the 777F are the same as the 777D,however the location has changed. The pump and motor are now located on the front of thefront frame crossmember. The pump and motor assembly also includes the brake release pumpsection (3) and the pre-lubrication (QuickEvac) pump section (4).

The secondary pressure switch (5) is also mounted next to the secondary steering pump. Thepressure switch detects if the wheels are being turned via the steering wheel when secondarysteering is activated. When the wheel is turned in a secondary steering condition, the pressureswitch will signal the Transmission/Chassis ECM.

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If the primary steering pressure switch signals the Transmission/Chassis ECM that the steeringsystem pressure is low, the ECM will energize the secondary steering relay located behind thecab. The secondary steering relay will then energize a second larger relay located on the leftframe, which will then energize the secondary steering motor.

The primary relief valve for the secondary steering is accessible through the small allen headplug (6). To check the setting of the secondary steering primary relief valve, do not start thetruck. Turn ON the key start switch and depress the secondary steering switch in the cab. Turnthe steering wheel hard to the left or right while the secondary steering pump is running.Secondary steering system pressures can be measured at the steering system pressure tap.

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Shown is a schematic of the steering hydraulic system in the HOLD position. The primarysteering pump pulls oil from the steering tank. All piston-type pumps produce a small amountof leakage to the case drain circuit for lubrication and cooling. The case drain oil flows to thesteering tank through a case drain filter.

Steering oil flows from the pump to the steering disable valve. When the steering disable valveis energized, oil is allowed to flow to the steering valve.

In the steering valve, a steering pressure switch monitors the output of the steering pump. Thesteering pressure switch cannot tolerate high steering system pressures. A pressure reducingvalve lowers the steering system pressure to the steering pressure switch.

If the steering pressure switch signals the Transmission/Chassis ECM that the steering systempressure is low, the ECM will then energize the secondary steering motor. Secondary steeringsupply oil will flow to the steering valve.

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Two relief valves are installed in the steering valve. The secondary steering back-up reliefvalve protects the secondary steering system if the relief valve on the secondary steering pumpmalfunctions. The primary steering back-up relief valve protects the primary steering system ifthe high pressure cutoff valve on the steering pump malfunctions.

Two check valves are located on the steering valve. The check valves are used to separate theprimary and secondary steering systems.

Steering supply oil flows to the HMU from the steering valve. Return oil from the HMU flowsthrough the steering valve and the steering filter to the steering tank.

The HMU meters the amount of oil sent to the steering cylinders by the speed at which thesteering wheel is turned. The faster the HMU is turned, the higher the flow sent to the steeringcylinders, and the faster the wheels will change direction.

Two crossover relief valves are installed in the top of the HMU. The crossover relief valves areinstalled in series with the left and right turn ports. If an outside force is applied to the frontwheels while the steering wheel is stationary, the crossover relief valves provide circuitprotection for the steering lines between the steering cylinders and the HMU. The crossoverrelief valves allow oil to transfer from one end of the steering cylinders to the opposite end ofthe cylinders.

When the Transmission/Chassis ECM energizes the secondary steering motor, load sensingsignal oil will flow from the secondary steering load sensing valve through the load sensingresolver to the HMU. The load sensing valve uses the load sensing signal pressure to controlthe amount of flow from the secondary steering pump to the steering valve.

The 777F Trucks use a dynamic load sensing steering system the same as the late model "D Series" Trucks. In a dynamic system, there is load sensing pressure and flow between theHMU and the steering pumps.

A load sensing pilot signal resolver valve is located in the steering disable valve. The resolvervalve allows load sensing signal oil to flow between the HMU and the primary steering pumpor the secondary steering pump. In the NO STEER position, oil flows to the HMU. In a LEFTor RIGHT STEER position, oil also flows from the HMU to the resolver valve.

Normally, the secondary steering pump is OFF and the resolver is closed from the HMU to thesecondary steering pump. The flow from the primary steering pump holds the resolver openand load sensing pilot signal pressure is present between the HMU and the piston pump flowcompensator.

The load sensing signal flow from the primary steering pump is also used for "thermal bleed"through the HMU. The "thermal bleed" is used to keep the HMU temperature the same as therest of the steering system. Keeping the HMU the same temperature prevents sticking.

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HOIST SYSTEM

The hoist system on the 777F Update trucks is electronically controlled by theTransmission/Chassis ECM. The hoist control system operates similar to the 777D trucks.

The main components in the hoist system are:

- Hoist control lever and position sensor (in cab)

- Hoist pump (1)

- Hoist control valve (2)

- Hoist cylinders (3)

- Hydraulic oil tank (4)

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The operator controls the hoist lever (arrow). The four positions of the hoist lever are RAISE,HOLD, FLOAT, and LOWER. The hoist valve has a fifth position referred to as the SNUBposition. The operator is unaware of the SNUB position because a corresponding lever positionis not provided. When the body is being lowered, just before the body contacts the frame, theTransmission/Chassis ECM signals the hoist lower solenoid to move the hoist valve spool to theSNUB position. In the SNUB position, the body float speed is reduced to prevent the bodyfrom making hard contact with the frame.

The hoist system can be enabled or disabled using ET. All trucks shipped from the factorywithout bodies installed are set at the DISABLED mode. The DISABLED mode is a test modeonly and will prevent the hoist cylinders from accidentally being activated. After the body isinstalled, change the hoist system to the ENABLED mode for the hoist system to functionproperly.

The truck should normally be operated with the hoist lever in the FLOAT position. Travelingwith the hoist in the FLOAT position will make sure the weight of the body is on the frame andbody pads and not on the hoist cylinders. The hoist control valve will actually be in the SNUBposition.

If the transmission is in REVERSE when the body is being raised, the hoist lever sensor is usedto shift the transmission to NEUTRAL. The transmission will remain in NEUTRAL until thehoist lever is moved into the HOLD or FLOAT position and the shift lever has been cycled intoand out of NEUTRAL.

NOTE: If the truck is started with the body raised and the hoist lever in FLOAT, thelever must be moved into HOLD and then FLOAT before the body will lower.

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The hoist lever (1) controls a position sensor (2). The PWM sensor sends duty cycle inputsignals to the Transmission/Chassis ECM. The hoist lever position sensor is a Hall effectposition sensor and operates the same as the transmission shift lever sensor (3) previouslydescribed. Depending on the position of the sensor and the corresponding duty cycle, one ofthe two solenoids located on the hoist valve is energized.

The four positions of the hoist lever are RAISE, HOLD, FLOAT, and LOWER, but since thesensor provides a duty cycle signal that changes for all positions of the hoist lever, the operatorcan modulate the speed of the hoist cylinders.

The hoist lever sensor performs three functions:

- Raises and lowers the body

- Neutralizes the transmission in REVERSE

- Starts a new TPMS cycle

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Shown is the hoist, converter, and brake hydraulic tank. The oil level is checked by openingthe small door (1) and looking at the sight gauge. The oil level should first be checked withcold oil and the engine stopped. The level should again be checked with warm oil and theengine running.

The lower sight gauge (2) can be used to fill the tank when the hoist cylinders are in theRAISED position. When the hoist cylinders are lowered, the hydraulic oil level will increase.After the hoist cylinders are lowered, check the hydraulic tank oil level with the upper sightgauge as explained above.

Check the hoist, converter, and brake hydraulic tank breather (3) for restriction. Clean the filterif it is restricted.

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Shown is the rear of the hoist, converter, and brake hydraulic tank. The hoist pump pulls oilfrom the tank through the suction screen (1) located in the rear of the tank. Oil returns from thehoist valve through the port (2).

Brake cooling oil returns to the hydraulic tank through the three upper ports (3).

Other ports located on the hydraulic tank are:

- Transmission charging pump suction (4)

- Transmission return (5)

- Torque converter pump suction (6)

- Brake cooling pump suction (7)

- Torque converter inlet relief valve return (8)

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The hoist pump (1) is a gear type pump that is attached to the drive gear at the rear of theengine. Mounted to the hoist pump is the brake cooling pump and the brake charging pump.Oil flows from the hoist pump to the hoist control valve.

The hoist system relief pressures are different in the RAISE and LOWER positions.

The body up switch must be in the RAISE position before the LOWER relief valve setting canbe tested. Move a magnet past the body up switch until the body up alert indicator on the dashturns ON. If the body up switch is in the LOWER position, the Transmission/Chassis ECMwill hold the hoist valve in the SNUB position and the LOWER relief valve will not open.

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In the HOLD, FLOAT and SNUB positions, the gauge will show the brake cooling systempressure, which is a result of the restriction in the coolers, brakes and hoses (normally muchlower than the actual oil cooler relief valve setting). The maximum pressure is limited by theoil cooler relief valve.

Hoist pump pressure can be checked at the pressure tap (2) on the pump.

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The hoist control valve (1) is located behind the engine on the right side of the frame. Thehoist valve is the same as the hoist control valve on the 777D.

The hoist valve uses torque converter lockup clutch pump oil as the pilot oil to shift thedirectional spool inside the hoist valve. Lockup clutch pump oil enters the hydraulic actuators (2) on both ends of the hoist valve.

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Pilot oil pressure is always present at both ends of the directional spool. Two solenoid valvesare used to drain the pilot oil from the ends of the directional spool, which then allows thespool to move. The solenoid on the right is the RAISE solenoid valve (1), and the solenoid onthe left is the LOWER solenoid valve (2).

The left pressure tap (3) is used to check the pilot pressure of the hoist lower solenoid. Theright pressure tap (4) is used to check the pilot pressure of the raise solenoid.

When the Transmission/Chassis ECM receives an input signal from the hoist lever sensor, theECM sends an output signal current between 0 and 1.9 amps to one of the solenoids. Theamount of current sent to the solenoid determines how much pilot oil is drained from the end ofthe directional spool and, therefore, how far the directional spool travels toward the solenoid.

An oil cooler relief valve is located in the hoist control valve behind the large plug (5). Therelief valve limits the brake oil cooling pressure when the hoist valve is in the HOLD, FLOAT,or SNUB position.

The hoist system relief pressures are controlled by the two relief valves located on top of thehoist valve. The RAISE relief valve (6) limits the pressure in the hoist system during RAISE.The LOWER relief valve (7) limits the pressure in the hoist system during LOWER.

NOTE: The hoist valve LOWER position (snub adjustment) is an adjustable parameterin the Transmission/Chassis ECM using Cat ET. The slight adjustment provides ameans to compensate for valve differences. This is the snub adjustment.

171

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Page 186: Serv1828 Txt

The hoist cylinder lower circuit pressure tap (1) and raise circuit pressure tap (2) are located onthe bottom of the hoist control valve (3).

The relief valve pressure setting is tested with the engine at HIGH IDLE and the hoist valve inthe RAISE or LOWER position.

The body up switch at the frame near the body pivot pin must be in the RAISE position beforethe LOWER relief valve setting can be tested. Move a magnet past the body up switch until thebody up alert indicator on the dash turns ON. If the body up switch is in the LOWER position,the Transmission/Chassis ECM will hold the hoist valve in the SNUB position and the LOWERrelief valve will not open.

An orifice plate is installed between the upper hose and the rod end port on both hoistcylinders. The orifice plate restricts the flow of oil from the rod end of the hoist cylinders.

The orifice plate also prevents cavitation of the cylinders when the body raises faster than thepump can supply oil to the cylinders (caused by a sudden shift of the load).

NOTE: If the snub feature is not adjusted correctly, residual pressure will exist in thehead side of the cylinders and the body will not rest on the frame. The raise circuitpressure tap should be used to ensure there is no residual pressure in the head side ofthe cylinders.

Otherwise, when checking the raise (high) circuit pressure, the pressure tap on the hoist pumpis easier to access.

172

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This illustration shows a sectional view of the hoist control valve in the HOLD position. Pilotoil pressure is present at both ends of the directional spool. The spool is held in the centeredposition by the centering springs and the pilot oil. Passages in the directional spool vent thedual stage relief valve signal stem to the tank. All the hoist pump oil flows through the brakeoil coolers to the rear brakes.

The position of the directional spool blocks the oil in the head end and rod end of the hoistcylinders.

A gauge connected to a pressure tap at the pump while the hoist valve is in the HOLD positionwill show the brake cooling system pressure, which is a result of the restriction in the coolers,brakes and hoses. The maximum pressure in the circuit should correspond to the setting of thebrake oil cooler relief valve.

SERV1828 - 187 - Text Reference01/07

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Page 188: Serv1828 Txt

174

In the RAISE position, the raise solenoid is ENERGIZED and drains pilot oil from the upperend of the directional spool. The directional spool moves up. Pump oil flows past the loadcheck valve and the directional spool to the head end of the hoist cylinders.

When the directional spool is initially shifted, the load check valve remains closed until thesupply pressure is higher than the pressure in the hoist cylinders. The load check valveprevents the body from dropping before the RAISE pressure increases.

The directional spool also sends hoist cylinder raise pressure to the dual stage relief valvesignal stem. The dual stage relief valve signal stem moves down and blocks the supplypressure from opening the low pressure relief valve.

Oil flowing from the rod end of the hoist cylinders flows freely through the brake oil cooler tothe brakes.

If the pressure in the head end of the hoist cylinders exceeds the relief valve settings, the highpressure relief valve will open. When the high pressure relief valve opens, the dump valvemoves to the left and pump oil flows to the tank.

SERV1828 - 188 - Text Reference01/07

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The high pressure hoist relief valve setting is checked at the hoist pump pressure tap or thehead end pressure tap. Check the relief pressure with the hoist lever in the RAISE position andthe engine at HIGH IDLE.

SERV1828 - 189 - Text Reference01/07

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175

In the LOWER (power down) position, the LOWER solenoid is energized and drains pilot oilfrom the lower end of the directional spool. The directional spool moves down.

Supply oil from the pump flows past the load check valve and the directional spool to the rodend of the hoist cylinders. Oil in the head end of the hoist cylinders flows to the tank throughholes in the directional spool. The supply oil in the rod end of the cylinders and the weight ofthe body move the cylinders to their retracted positions.

Just before the body contacts the frame, the body up switch sends a signal to theTransmission/Chassis ECM to move the directional spool to the SNUB position. In the SNUBposition, the directional spool moves slightly to restrict the flow of head end oil through onlysome of the holes in the spool which allows the body to lower gradually.

The directional spool also vents the passage to the dual stage relief valve signal stem. The dualstage relief valve signal stem allows supply pressure to be limited by the low pressure reliefvalve.

If the pressure in the rod end of the hoist cylinders is too high, the low pressure relief valve willopen. When the low pressure relief valve opens, the dump valve moves to the left and pump oilflows to the tank.

SERV1828 - 190 - Text Reference01/07

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Page 191: Serv1828 Txt

The low pressure hoist relief valve setting is checked at the rod end pressure tap. Check therelief pressures with the hoist lever in the LOWER position and the engine at HIGH IDLE.

The body up switch must be in the RAISE position before the LOWER relief valve setting canbe tested. Move a magnet past the body up switch until the body up alert indicator on the dashturns ON. If the body up switch is in the LOWER position, the Transmission/Chassis ECMwill hold the hoist valve in the SNUB position and the LOWER relief valve will not open.

SERV1828 - 191 - Text Reference01/07

Page 192: Serv1828 Txt

176

In the FLOAT position, the LOWER solenoid is partially energized and drains some of the pilotoil at the lower end of the directional spool to the tank. The directional spool moves down.Because the pilot oil is only partially drained, the directional spool does not move down as faras during LOWER (power down).

Pump supply oil flows past the load check valve and the directional spool to the rod end of thehoist cylinders. Oil in the head end of the hoist cylinders flows to the tank. The position of thedirectional spool permits the pressure of the oil flowing to the brake oil cooler to be felt at therod end of the hoist cylinders.

The truck should normally be operated with the hoist lever in the FLOAT position. Travelingwith the hoist in the FLOAT position will make sure the weight of the body is on the frame andbody pads and not on the hoist cylinders. The hoist valve will actually be in the SNUBposition.

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In the SNUB position as the body is lowered, just before the body contacts the frame, the bodyup switch sends a signal to the Transmission/Chassis ECM to move the directional spool to theSNUB position. In the SNUB position, the directional spool moves slightly to a positionbetween HOLD and FLOAT. The SNUB position restricts the flow of oil and lowers the bodygradually.

The operator does not control the SNUB position. When the hoist lever is in the LOWER orFLOAT position and the body up switch is in the DOWN position, the hoist control valve is inthe SNUB position.

A gauge connected to the rod end pressure tap while the hoist control valve is in the SNUBposition will show the brake cooling system pressure, which is a result of the restriction in thecoolers, brakes, and hoses. The maximum pressure in the circuit should correspond to thesetting of the brake oil cooler relief valve.

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Two-stage hoist cylinders (1) are used to raise the body. Oil flows from the hoist control valveto the two hoist cylinders when the directional spool in the hoist control valve is not in HOLD.

Check the condition of the body pads (2) for wear or damage.

Hoist pilot pressure is required to lower the body with a dead engine. The towing pump can beused to provide the hoist pilot oil.

To lower the body with a dead engine:

1. Move towing valve to TOW position.

2. Turn key ON.

3. Hold hoist lever in RAISE for 15 seconds.

4. Move hoist lever to HOLD and then FLOAT.

5. Press secondary steering switch and body will lower.

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This illustration shows the hoist hydraulic system in the HOLD position. The hoist pump pullsoil from the hydraulic tank through the suction screen located in the rear of the tank. Oil flowsfrom the hoist pump to the hoist control valve.

When the hoist control valve is in the HOLD, FLOAT, or SNUB position, all the hoist pump oilflows through the brake oil coolers located on the right side of the engine. Oil flows from theoil coolers, through the brakes, and returns to the hydraulic tank.

NOTE: If the truck is equipped with the optional caliper type front brake system, thebrake cooling pump is not installed and oil from the hoist pump will flow to only therear brakes.

A brake cooling relief valve is located in the hoist control valve. The relief valve limits thebrake oil cooling pressure when the hoist control valve is in the HOLD, FLOAT, or SNUBposition.

The hoist valve uses torque converter lockup clutch pump oil as the pilot oil to shift thedirectional spool inside the hoist control valve. Oil flows from the lockup clutch pump to bothends of the hoist control valve.

SERV1828 - 195 - Text Reference01/07

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Page 196: Serv1828 Txt

Pilot pressure is always present at both ends of the directional spool. Two solenoid valves areused to drain the pilot oil from the ends of the directional spool, which then allows thecentering springs and the pressure on the opposite end of the spool to move the spool. Whenthe RAISE solenoid is energized, the directional spool will move toward the RAISE solenoid.

The RAISE and LOWER solenoid valves constantly receive approximately 300 millivolts at afrequency of 80 Hz from the Transmission/Chassis ECM when they are in any position exceptHOLD. The excitation, referred to as "dither," is used to keep the solenoids in a ready state forquick response.

When the Transmission/Chassis ECM receives an input signal from the hoist lever sensor, theECM sends an output signal current between 0 and 1.9 amps to one of the solenoids. Theamount of current sent to the solenoid determines how much pilot oil is drained from the end ofthe directional spool and, therefore, the distance that the directional spool travels.

The truck should normally be operated with the hoist lever in the FLOAT position. Travelingwith the hoist in the FLOAT position will make sure the weight of the body is on the frame andbody pads and not on the hoist cylinders. The hoist valve will actually be in the SNUBposition.

When the hoist control valve is in the RAISE position, pump supply oil flows to the head endof the hoist cylinders. Pump supply oil also flows to the dual stage signal spool and moves thespool to the left. When the dual stage signal spool moves to the left, pump supply oil isblocked from the LOWER relief valve, and the RAISE relief valve will limit the hoist systempressure.

When the hoist control valve is in the LOWER (power down), FLOAT, or SNUB position,pump supply oil flows to the rod end of the hoist cylinders. Pump supply oil is blocked fromthe dual stage signal spool and the spring holds the spool in the right position. When the dualstage signal spool is in the right position, pump supply oil can flow to the LOWER relief valve,and hoist system pressure is controlled by the LOWER relief valve.

An orifice plate is installed between the upper hose and the rod end port on both hoistcylinders. The orifice plate prevents cavitation of the cylinders when the body raises fasterthan the pump can supply oil to the cylinders (caused by a sudden shift of the load).

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BRAKE SYSTEM

Two separate brake systems are used on the 777F. The two brake systems are theservice/retarder brake system and the parking/secondary brake system. The parking/secondarybrakes are spring engaged and hydraulically released. The service/retarder brakes arehydraulically engaged and spring released.

The braking system is also equipped with a Brake ECM that controls the braking systemfunctions, including the Automatic Retarder Control (ARC) and the Traction Control System (TCS).

The air system on the previous model trucks has been completely removed.

The main components in the braking system are:

- Brake charging pump (1)

- Brake cooling pump (standard oilcooled front brakes) (2)

- Accumulator charging valve (3)

- Brake accumulators (4)

SERV1828 - 197 - Text Reference01/07

- Cab brake manifold (5)

- Service brake valve (6)

- Brake oil filter (7)

- Front slack adjuster (8)

- Brake accumulator check valve (9)

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Page 198: Serv1828 Txt

The rear brakes on the 777F Trucks are oil cooled. Shown is a cutaway illustration of an oilcooled brake assembly. The brakes are environmentally sealed and adjustment free. Oilcontinually flows through the brake discs for cooling. Duo-Cone seals prevent the cooling oilfrom leaking to the ground or transferring into the axle housing. The wheel bearing adjustmentmust be maintained to keep the Duo-Cone seals from leaking.

The smaller piston (yellow) is used to engage the secondary and parking brakes. The parkingbrakes are spring engaged and hydraulically released.

The larger piston (purple) is used to engage the service and retarder brakes. The service andretarder brakes are engaged hydraulically and released by spring force.

181

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The standard oil cooled front brakes are also environmentally sealed and adjustment free. Thepiston (yellow) is used to ENGAGE the service/retarder brakes. The front brakes do not have asecond piston for the parking/secondary brakes.

When the wheel is removed for service, the small plug at the lower left must be removed (thebrake assembly is equipped with two similar plugs). Two 3/8 inch bolts must be installed at theplug locations to hold the brake discs and plates in position during wheel removal. The boltsensure proper alignment of the teeth on the discs and plates during installation.

182

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With the optional disc and caliper design brakes, the brake caliper assemblies are fastened tothe spindle and do not rotate. The brake disc is fastened to the wheel and rotates with thewheel. Air can be bled from the front brakes through the bleed valves.

During brake application, hydraulic oil from the brake cylinders forces the brake pistons againstthe brake carrier linings (brake pads). The brake linings are forced against the disc to stop therotation of the wheel.

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The brake charging pump (1), the brake oil cooling pump (2), and the hoist pump (3) aremounted to the pump drive gear on the left rear side of the engine. The 777F brake systemaccumulators are charged by the brake charging pump, which supplies oil to the accumulatorcharging valve. The oil cooling pump sends oil to the oil coolers before the oil flows to thefront and rear brakes for brake cooling.

NOTE: The brake oil cooling pump is not installed on trucks with the optional calipertype front brakes.

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The brake system filter (1) is located on the left outer rear frame next to the left rear strutmount. The brake filter includes a filter bypass switch (2), which sends a signal to the BrakeECM if the filter is restricted. The Brake ECM sends a signal to the monitoring system, whichilluminates the brake system-check indicator lamp. Brake system pressure can be checked atthe tap (3) located in the hydraulic line to the accumulator charging valve.

186

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The accumulator charging valve (1) is located on the left side of the frame near the brakeaccumulators. The accumulator charging valve directs oil to the brake accumulators, brake oilcoolers, and the tank. Once the accumulators are charged, the excess oil flow is sent to cool thebrakes before returning to the tank.

The Brake ECM monitors the pressure in the service brake accumulators with the brakeaccumulator pressure switch (2). If the pressure in the service brake accumulators is low, theBrake ECM will signal the monitoring system to turn on the brake system-check indicatorlamp. A relief (3) valve limits the pressure in the brake charging circuit.

The pressure tap (5) on the charging valve is used to check the oil pressure in the service brakeaccumulators.

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The accumulator charging valve maintains the pressure in the accumulators at a constant ratewhile the engine is running. If the machine has lost power or the hydraulic pump has failed, thepressure in the accumulators will permit several applications of the service brakes.

This illustration shows the accumulator charging valve in the CUT-IN position. When theaccumulator oil pressure decreases below a certain point, the accumulator charging valvereaches the cut-in pressure setting. The pressure decrease allows spring force to move the cut-in/cut-out spool to the left and oil flows to the right end of the unloading valve. The orificein the unloading valve restricts the pump flow to the brake cooling system. Oil flow to thebrake accumulators increases and the accumulators are charged.

The accumulator oil pressure switch sends a signal to the Brake ECM to alert the operator whenthe brake oil pressure drops below the minimum operating pressure.

SERV1828 - 204 - Text Reference01/07

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Page 205: Serv1828 Txt

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This illustration shows the accumulator charging valve in the CUT-OUT position. When theaccumulator oil pressure increases to the cut-out pressure setting, the increased pressure causesthe cut-in/cut-out spool to move right against spring force. Oil at the right end of the unloadingvalve flows to the tank. Oil pressure on the left end of the unloading spool overcomes thedecreased oil pressure on the right end of the spool and spring force. Most of the brakecharging pump oil now flows to the brake cooling system.

The check valve prevents high accumulator oil pressure from flowing to the brake coolingsystem.

The accumulator charging valve remains in the CUT-OUT position until the pressure in theaccumulators decreases to the cut-in pressure setting.

The pressure relief valve regulates the oil pressure in the brake circuit. Any excess oil that isnot required by the brake cooling system or the brake circuit is diverted back to the hydraulicoil tank.

The pressure relief valve is set much higher than cut-out pressure and is used as a backup reliefvalve.

SERV1828 - 205 - Text Reference01/07

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Page 206: Serv1828 Txt

There are the three brake accumulators for the 777F located on the left side of the frame. Theservice brake accumulators (1) and parking brake accumulator (2) are charged by the brakecharging pump and supply the required oil flow to engage the front and rear service brakes andrelease the rear parking brakes.

A check valve in the circuit between the parking brake accumulator and the service brakeaccumulators allows only the parking brake accumulator to be charged when using the electricbrake release pump.

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Page 207: Serv1828 Txt

The cab brake manifold (1) is mounted below the cab on the left upper frame. The cab brakemanifold contains the ARC control solenoid (2) and the front service brake solenoid (3).

The ARC control solenoid is part of the ARC system. The ARC system uses the rear servicebrakes and the front oil cooled brakes to automatically control the speed of the truck.

The service brake pressure switch (4) is located near the cab brake manifold toward the front ofthe machine. The service brake pressure switch sends a signal to the Brake ECM when theservice brakes are engaged. The Brake ECM will use the signal from the pressure switch toenergize the stop lamp relay (located in cab) and turn on the brake lights. In a low pressuresituation, the Brake ECM will signal the monitoring system to activate the brake system-checkindicator.

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The service brake valve (1) is mounted below the floor of the operator’s cab. When the servicebrake pedal (2) is depressed, an internal spool directs oil flow from the service brakeaccumulators to the rear service brakes.

The amount of oil flow to the front service brakes is determined by the Brake ECM based on asignal from the service brake pedal position sensor (3). The Brake ECM allows some oil fromthe brake accumulators to flow to the front brakes by controlling the position of the front brakesolenoid located in the cab brake manifold.

NOTE: If the front brake switch (optional front caliper type brakes only) is activated,the Brake ECM will command all oil to flow to the rear brakes.

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When the manual retarder lever (1) is activated, a PWM signal is sent to the Brake ECM. TheBrake ECM sends a signal to the ARC solenoid and the front brake solenoid. The solenoidscontrol the amount of oil flow to the service brakes based on the position of the retarder lever.

If the ARC switch (2) is activated, the Brake ECM sends a signal to the ARC solenoid and thefront brake solenoid. The solenoids control the amount of oil flow to the service brakes basedupon the input signals that the Brake ECM receives from the engine speed sensor.

NOTE: If the truck is equipped with the optional front caliper type brakes, the BrakeECM will command all oil to flow to the rear brakes when the retarder lever is movedor the ARC switch is activated.

The optional engine brake switch (3) is also an input to the Brake ECM. The Brake ECMcommunicates the status of the brake switch to the Engine ECM via the Cat Data Link. TheEngine ECM controls the compression brake application (if equipped).

The front brake switch (4) is installed on machines with caliper type front brakes. Whenactivated, the front brake switch sends a signal to the Brake ECM which allows the front brakesto be engaged when the brake pedal is depressed. When the front brake switch is in the OFFposition, only the rear brakes will be engaged when the brake pedal is depressed.

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The 777F has two slack adjusters. The top illustration shows the rear slack adjuster (1). Therear slack adjuster is located above the rear differential. The bottom illustration shows the frontslack adjuster (2). The front slack adjuster is located on the left strut frame support.

The slack adjusters compensate for brake disc wear by allowing a small volume of oil to flowthrough the slack adjuster and remain between the slack adjuster and the brake piston underlow pressure. The slack adjusters maintain a slight pressure on the brake piston at all times.

Brake cooling oil pressure maintains a small clearance between the brake discs.

The service brake oil pressure can be tested at the taps (3) located on top of the slack adjusters.

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This illustration shows sectional views of the slack adjuster when the brakes are RELEASEDand ENGAGED.

When the brakes are ENGAGED, oil from the brake cylinder enters the slack adjuster and thetwo large pistons move outward. Each large piston supplies oil to one wheel brake. The largepistons pressurize the oil to the service brake pistons and ENGAGE the brakes.

Normally, the service brakes are FULLY ENGAGED before the large pistons in the slackadjuster reach the end of their stroke. As the brake discs wear, the service brake piston willtravel farther to FULLY ENGAGE the brakes. When the service brake piston travels farther,the large piston in the slack adjuster moves farther out and contacts the end cover. The pressurein the slack adjuster increases until the small piston moves and allows makeup oil from thebrake cylinder to flow to the service brake piston.

When the brakes are RELEASED, the springs in the service brakes push the service brakepistons away from the brake discs. The oil from the service brake pistons pushes the largepistons in the slack adjuster to the center of the slack adjuster. Makeup oil that was used toENGAGE the brakes is replenished at the brake cylinder from the makeup tank.

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The spring behind the large piston causes some oil pressure to be felt on the service brakepiston when the brakes are RELEASED. Keeping some pressure on the brake piston providesrapid brake engagement with a minimum amount of brake cylinder piston travel.

The slack adjusters can be checked for correct operation by opening the service brake bleedscrew with the brakes RELEASED. A small amount of oil should flow from the bleed screwwhen the screw is opened. The small flow of oil verifies that the spring behind the large pistonin the slack adjuster is maintaining some pressure on the service brake piston.

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The service brake bleed screw (1) is identified by an "S" on the brake anchor plate casting nextto the screw. The parking brake bleed screw (2) is identified by a "P" on the casting.

Another check to verify correct slack adjuster operation is to connect a gauge to the pressuretap on top of the slack adjuster and another gauge at the service brake bleed screw location onthe brake anchor plate casting.

With the service brake pedal depressed, the pressure reading on both gauges should beapproximately the same. When the brakes are RELEASED, the pressure at the slack adjustershould return to zero. The pressure at the service brake bleed screw location should return tothe residual pressure held on the brakes by the slack adjuster piston.

If the slack adjuster residual pressure is too low, it could indicate a failed slack adjuster. Highresidual pressure may indicate a failed slack adjuster or warped brake discs. To check forwarped brake discs, rotate the wheel to see if the pressure fluctuates. If the pressure fluctuateswhile rotating the wheel, the brake discs are probably warped and should be replaced.

To check for brake cooling oil leakage, block the brake cooling ports and pressurize each brakeassembly to a maximum of 138 kPa (20 psi). Close off the air supply source and observe thepressure trapped in the brake assembly for five minutes. The trapped pressure should notdecrease.

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The parking brake valve (1) is located on the inside left frame rail behind the center crossmember. The parking valve receives oil flow from the parking brake accumulator. Containedwithin the valve is a parking brake solenoid valve (2) and a purge solenoid valve (3).

When the parking brake solenoid is energized by the Brake ECM, the parking brake valvedirects oil flow through the TCS valve to release the rear parking brakes. There are no parkingbrakes on the front wheels. When the transmission shift lever is moved to PARK a signal issent to the Brake ECM to engage the parking brakes. There is not a separate parking brakecontrol switch. The secondary brake pressure switch (4) sends a signal to inform theTransmission/Chassis ECM that the secondary/parking brake is engaged.

When the machine is shut down, the purge solenoid is energized by the Transmission/ChassisECM and the purge valve drains the brake accumulators to tank.

202

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The parking brake pressure can be checked at the left parking brake tap (1) and at the rightparking brake tap (2).

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The secondary brake pedal position sensor (arrow) is located on the back of the secondarybrake pedal. The position sensor sends a signal to the Brake ECM indicating the position of thesecondary brake pedal. The Brake ECM sends a signal to the parking brake solenoid whichcontrols the secondary brake application at the rear brakes.

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The secondary steering/brake release/QuickEvac pump and motor are located on the front of thefront frame crossmember as previously shown. The brake retract pump section (arrow)provides oil to release the parking brakes and hoist pilot oil for lowering the body on truckswith a dead engine.

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The diverter (towing) valve (arrow) is located on the left hoist cylinder frame support. Thediverter valve is used to unlock the brakes for towing and must be manually shifted beforetowing.

Once the valve is shifted, oil flow from the electric secondary steering/brake retract pump isdirected to the parking brake valve to release the parking brake.

To release the parking brakes for service work or towing, the electric motor on the pump isenergized by the brake release switch located in the cab.

When the key start switch is turned ON, the secondary steering system is energized for threeseconds to check the system. Since the towing pump is driven by the same electric motor asthe secondary steering pump, the diverter valve allows the towing pump oil to flow directly tothe hydraulic tank during the secondary steering test.

To shift the diverter valve, loosen the two diverter valve clamp bolts and slide the plate and thespool to the left. After the spool is shifted, tighten the diverter valve clamp bolts. When theelectric motor is energized, supply oil can flow from the towing pump, through the divertervalve, to the parking brake valve.

The brake release pump is also used to provide pilot oil to lower the body when the engine isoff.

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208

This schematic shows the oil flow through the brake cooling system on the 777F Trucks withstandard oil cooled front brakes. The brake cooling pump supplies oil to the brake coolers andthe front and rear brakes. The brake cooling system also receives oil from the followingcomponents:

- Hoist valve (in the HOLD, FLOAT, and SNUB positions)

- Accumulator charging valve

- Torque converter lockup clutch relief valve

- Torque converter outlet relief valve

The pressure in the brake cooling system is limited by a relief valve located in the hoist valve.The relief valve is usually needed only when the brake cooling oil is cold. When brake coolingoil is at operating temperature, the brake cooling oil pressure is usually much lower than thesetting of the oil cooling relief valve.

NOTE: On trucks equipped with the optional caliper type front brakes, the brakecooling system oil flows only to the rear brakes.

SERV1828 - 219 - Text Reference01/07

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The brake oil coolers (arrows) are located on the right side of the engine. Engine coolant fromthe water pump flows around the brake oil coolers and back to the cylinder block. The enginecoolant transfers the heat from the brake oil system to the engine coolant.

Oil from the brake cooling pump flows through screens (not shown) before flowing through thebrake oil coolers.

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The brake cooling pump (1) is a gear-type pump that is attached to the drive gear at the rear ofthe engine. The brake cooling pump is located between the hoist pump (2) and the brakecharging pump (3). Oil flows from the brake cooling pump to the brake oil coolers.

NOTE: The brake oil cooling pump is not installed on trucks with the optional calipertype front brakes.

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Shown is the left rear brake housing. Brake cooling oil pressure can be tested at the two taps (arrows) located in the brake cooling oil tubes. One tap is located on the brake coolinginlet tube and another tap is located on the brake cooling outlet tube. The pressure measured atthe brake inlet tube (from the oil coolers) will always be higher than the pressure measured atthe brake outlet tube.

A brake oil temperature sensor is located in a brake oil cooling tube on the truck. The brake oiltemperature sensor sends a signal to the Brake ECM indicating brake oil temperature. TheBrake ECM will send a signal over the Cat Data Link, which informs the monitoring system todisplay the temperature on the brake temperature gauge.

The most common cause of high brake cooling oil temperature is operating the truck in a gearrange which is too high for the grade and not maintaining a high enough engine speed. Theengine speed should be maintained at approximately 1900 rpm during long downhill hauls.

Make sure the oil cooling relief valve is not stuck open. Also, make sure the pistons in theslack adjuster are not stuck and holding too much pressure on the brakes.

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212

This schematic shows the major components of the brake system with the standard oil cooledfront brakes. The front slack adjuster is not included on the optional caliper type front brakesystem.

Oil is drawn from the hydraulic tank by the brake charging pump. Oil flows through the brakefilter to the accumulator charging valve. The accumulator charging valve directs supply oil tothe brake accumulators. The accumulator charging valve also controls the cut-in and cut-outpressure. When the accumulators are charged, the charging valve will direct excess pump flowto the brake cooling system.

The service brake accumulators provide oil flow through the cab manifold to the service brakecontrol valve. Oil flowing into the cab manifold also flows to the ARC control solenoid andfront brake solenoid. When the operator depresses the service brake pedal, the service brakecontrol valve directs pump flow to the rear service brakes to stop the truck.

The front brakes are only engaged when the Brake ECM energizes the front brake solenoid.With the standard oil cooled front brakes, the Brake ECM determines when to energize thefront brake solenoid when the service brake pedal is depressed. With the optional caliper typefront brakes, the Brake ECM will energize the front brake solenoid when the front brakelockout switch in the cab is activated.

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The Brake ECM controls the modulation of the ARC solenoid and front brake solenoid, whichcontrols truck braking when the ARC system is ON.

Oil from the parking brake accumulator flows to the parking brake valve and the towingdiverter valve. When the parking brake is activated, the supply oil for releasing the parkingbrakes is directed to the tank and the parking brakes are engaged by spring force. When theparking brake solenoid is energized (parking brake de-activated), the parking brake valvedirects oil to the TCS valve. The pressure reducing valves in the TCS valve direct oil to releasethe parking brakes.

The diverter valve, under normal operation, is closed and blocks the oil flow from the electricbrake retract pump. If the truck is to be towed with a dead engine, the diverter valve must beshifted manually. When manually shifted, the diverter valve directs oil flow from the electricbrake retract pump to the parking brake valve to release the rear brakes.

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213

Brake Electronic Control System

The 777F Trucks are equipped with a Brake ECM for controlling the parking brake and frontservice brake applications, the ARC system, and the TCS. The following two possiblearrangements can be installed on a truck:

- ARC only

- ARC and TCS

The Brake ECM receives information from various input components such as the engine speedsensor, the service brake pedal position sensor, the ARC switch, and the wheel speed sensors.

Based on the input information, the Brake ECM controls the front service brake applicationwhen the service brake pedal is depressed or the front and rear service brake application whenthe ARC system is activated. The Brake ECM also controls when the parking brakes shouldengage for the TCS and parking brake application when the parking brake is manuallyactivated.

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Output components include the ARC solenoid, the front service brake solenoid, the TCSselector and proportional solenoids, and the parking brake solenoid.

The compression brake switch is also an input to the Brake ECM. When the compressionbrake switch is activated, the Brake ECM sends a signal over the Cat Data Link to the EngineECM. The Engine ECM controls the engine compression brake, which was covered earlier inthe presentation.

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The Brake ECM (arrow) is located in the compartment at the rear of the cab. The Brake ECMperforms the brake control functions, and controls the ARC system and TCS.

The Brake ECM is an A4M1 module with two 70-pin connectors. The Brake ECMcommunicates with the Engine ECM, Transmission/Chassis ECM, and monitoring system overthe CAT Data Link and can communicate with some attachments over the CAN Datalink.

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215

When the service brake pedal is depressed, the service brake valve directs oil from the servicebrake accumulators to the rear brakes and sends a PWM signal to the Brake ECM via theservice brake pedal position sensor. The Brake ECM then determines what signal to send to thefront service brake solenoid based on the following conditions:

1. If the truck is equipped with the standard oil cooled front brakes, the Brake ECMsignals the front service brake solenoid to direct oil from the service brake accumulatorsto the front and rear brakes.

2. If the truck is equipped with the optional caliper type front brakes, the Brake ECMreceives a signal from the front brake lockout switch in the cab. If the lockout switch isOFF, the Brake ECM signals the front service brake solenoid to direct oil from theservice brake accumulators to the front and rear brakes the same as the oil cooled frontbrakes.

NOTE: Oil flow to the front and rear brakes may not be proportional. When the pedalis initially depressed, more oil is directed to the rear brakes. As the pedal is depressedfarther more oil is sent to the front brakes in proportion to the rear until full front brakepressure is present at full pedal travel.

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3. If the truck is equipped with the optional caliper type front brakes, and the lockoutswitch is ON, the Brake ECM de-energizes the front service brake solenoid. Oil flow tothe front brakes is blocked and only the rear brakes are used to stop the truck.

The Brake ECM also de-energizes the ARC solenoid when the ARC switch in the cab is OFFand the manual retarder lever is in the NEUTRAL position. The manual retarder lever alsocontrols the service brake application using the front brake solenoid and the ARC solenoid.

When the retarder lever is moved, a PWM signal is sent to the Brake ECM. The Brake ECMthen determines what signal to send to the ARC solenoid and front service brake solenoid basedon the following conditions:

1. If the truck is equipped with the standard oil cooled front brakes, the Brake ECMsignals the ARC solenoid and the front service brake solenoid to divide the oil flowfrom the service brake accumulators between the front and rear brakes.

2. If the truck is equipped with the optional caliper type front brakes, the Brake ECM de-energizes the front service brake solenoid. Oil flow to the front brakes is blockedand only the rear brakes are used to stop the truck with the retarder lever.

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216

Automatic Retarder Control (ARC)

The ARC system receives signals from several switches and sensors. The main inputs to theBrake ECM for the ARC system are the ARC switch and engine speed sensor. The Brake ECManalyzes the various input signals and sends output signals to the ARC solenoid and frontservice brake solenoid.

NOTE: If the truck is equipped with the optional front caliper type brakes, the BrakeECM will de-energize the front service brake solenoid when the ARC system isactivated.

The ARC system function is to modulate truck braking (retarding) when descending a longgrade to maintain a constant engine speed. The ARC system engages the rear service brakesand the front oil cooled service brakes. If the ARC switch is moved to the ON position, theARC system will be activated if the throttle pedal is not depressed and the parking/secondarybrakes are RELEASED. The ARC system is disabled when the throttle is depressed or whenthe parking/secondary brakes are ENGAGED.

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The ARC is set at the factory to maintain a constant engine speed of 1938 (engine speed isprogrammable from 1838 to 1938 rpm). When the ARC initially takes control of retarding, theengine speed may oscillate out of the ± 50 rpm target, but the engine speed should stabilizewithin a few seconds.

For proper operation of the ARC system, the operator needs only to activate the control withthe ARC switch and select the correct gear for the grade, load, and ground conditions. TheARC system is designed to allow the transmission to upshift to the gear selected by the shiftlever. After the transmission shifts to the gear selected by the operator and the engine speedexceeds 2285 rpm, the ARC system will apply the retarder as needed to maintain a constantengine speed.

The ARC system also provides engine overspeed protection. If an unsafe engine speed isreached, the ARC will engage the brakes, even if the ARC switch is in the OFF position and thethrottle is depressed.

Trucks approaching an overspeed condition will sound a horn and activate a light. If theoperator ignores the light and horn, the ARC will engage the retarder. If the engine speedcontinues to increase, the Transmission/Chassis ECM will either upshift (one gear only aboveshift lever position) or unlock the torque converter (if the shift lever is in the top gear position).

The ARC also provides service personnel with enhanced diagnostic capabilities through the useof onboard memory, which stores possible faults, solenoid cycle counts and other serviceinformation for retrieval at the time of service.

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217

Traction Control System (TCS)

The Traction Control System (TCS) uses the rear parking/secondary brakes (spring engaged andhydraulically released) to decrease the revolutions of a spinning wheel. The TCS allows the tirewith better underfoot conditions to receive an increased amount of torque. The system iscontrolled by the Brake ECM and operates the same as the 777D TCS.

The Brake ECM monitors the drive wheels through four input signals: one at each drive axle,and two at the transmission output shaft. When a spinning drive wheel is detected, the BrakeECM sends a signal to the selector and proportional valves which ENGAGE the brake of theaffected wheel. When the condition has improved and the ratio between the right and left axlesreturns to 1:1, the Brake ECM sends a signal to RELEASE the brake.

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The service brake pressure switch provides an input signal to the Brake ECM from theTransmission/Chassis ECM through the CAT Data Link and performs the following twofunctions:

1. When the service brakes or retarder are ENGAGED, the TCS function is stopped.

2. The service brake pressure switch provides the input signal needed to perform adiagnostic test. When the TCS test switch and the retarder lever are ENGAGEDsimultaneously, the TCS will engage each rear brake independently. Install twopressure gauges on the TCS valve, and observe the pressure readings during the testcycle. The left brake pressure will decrease and increase. After a short pause, the rightbrake pressure will decrease and increase. The test will repeat as long as the TCS testswitch and the retarder lever are ENGAGED.

The TCS valve has left and right brake release pressure taps. When the proportional solenoid isENERGIZED, Cat ET will show 68% when the brake is FULLY ENGAGED.

NOTE: During the diagnostic test, the parking/secondary brakes must be released.

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Shown is the right rear wheel speed sensor (arrow) looking toward the rear of the truck. TheTCS monitors the drive wheels through four input speed signals: one at each drive axle, andtwo at the transmission output shaft.

The transmission output speed sensors monitor the ground speed of the machine and provideinput signals to the Brake ECM through the CAT Data Link. The TCS uses the transmissionoutput speed sensors to disable the TCS when ground speed is above 19.3 km/h (12 mph).

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The TCS valve is mounted inside the left frame rail toward the rear of the machine. Twosolenoids are mounted on the valve.

Electrical signals from the Brake ECM cause the selector solenoid valve (1) to shift and selecteither the left or right parking brake. If the selector valve shifts to the left parking brakehydraulic circuit, the control oil is drained. The left reducing spool of the control valve can thenshift and engage the parking brake.

The proportional solenoid valve (2) controls the volume of oil being drained from the selectedparking brake control circuit. The rate of flow is controlled by a signal from the Brake ECM.

The pressure taps (3) can be used to test the left and right brake release pressures whenperforming diagnostic tests on the TCS. At HIGH IDLE, the pressure at the taps in the TCSvalve will be approximately 138 kPa (20 psi) less than the brake release pressure tested at thewheels.

The pressure taps are also used to provide parking brake dragging information to the servicetechnician. If the parking brakes are released, as sensed by the secondary brake pressure switchon the parking brake control valve, and parking brake pressure is below 3445 kPa (500 psi), aparking brake dragging event will be logged in the Brake ECM. The event can be viewed withCat ET.

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This illustration shows the TCS valve with the engine running and the brakes RELEASED.

With the engine running, oil flows from the brake charging pump to the parking brake valve.When the operator moves the transmission lever out of the PARK position, the Brake ECMenergizes the parking brake solenoid which directs oil flow to the TCS valve.

In the TCS valve, oil flows through a screen and orifices to the selector solenoid and the brakereducing valves. When the TCS is not activated, the oil is blocked at the selector solenoid. Oilpressure moves the brake reducing solenoids to the left and oil from the brake charging pump isdirected to the parking brakes. The parking brakes are RELEASED.

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This illustration shows the TCS valve with the engine running and the left brake ENGAGED.

When signals from the sensors indicate that the left wheel is spinning 60% faster than the rightwheel, the Brake ECM sends a signal to the selector solenoid valve and the proportionalsolenoid valve. The selector solenoid valve shifts up to open a passage between the right endof the left brake pressure reducing valve and the proportional solenoid valve.

The torque converter lockup pump oil provides signal oil to the drain ball check which allowsoil from the TCS valve to return to the tank.

The proportional solenoid valve opens a passage from the selector solenoid valve to drainthrough the drain ball check. The proportional solenoid valve also controls the rate at whichthe oil is allowed to drain. Control circuit oil drains through the selector valve and enters theproportional valve.

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The reducing valve spool for the left parking brake shifts and blocks oil flow to the parkingbrake. Oil in the left parking brake control circuit begins to drain and the left parking brakebegins to ENGAGE. The left brake orifice restricts the flow of oil from the parking brakevalve.

When the signals from the sensors indicate that the left wheel is no longer spinning, the BrakeECM stops sending signals to the selector solenoid and the proportional solenoid. The selectorsolenoid valve and proportional solenoid valve block the passage to drain and allow the controlcircuit pressure to increase.

The left brake reducing valve spool shifts to the left and blocks the passage to drain. Parkingbrake oil is directed to the left parking brake and the brake is RELEASED.

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CONCLUSION

This presentation has provided a basic introduction to the Caterpillar 777F Off-highway Truck.All the major component locations were identified and the major systems were discussed.When used in conjunction with the service manual, the information in this package shouldpermit the technician to analyze problems in any of the major systems on these trucks.

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Page 239: Serv1828 Txt

SERV1828 - 239 - Text Reference01/07

1. Right side of 777F Truck2. Left side of 777F truck3. Front of 777F truck4. Rear of 777F truck5. Walk around inspection6. 10 hour daily maintenance checks7. Front wheel bearing oil level8. Suspension cylinder grease fitting9. Caliper disk brake linings

10. Primary fuel filter11. Dual engine oil filters12. Scheduled Oil Sampling (SOS) coolant

analysis tap13. Transmission filters14. Torque converter charging filter15. Fuel tank16. Final drive drain plug17. Differential18. Body up retaining pins19. Hydraulic tank20. Manual engine shutdown switch21. Battery disconnect switch22. Battery disconnect switch and auxiliary

start receptacle23. Engine lockout control switch24. Battery and coolant sight glass location25. Steering system oil tank26. Air intake system components27. Engine oil level dipstick28. Windshield washer fluid level29. Operator's station30. Cab air filter31. 777F operator compartment32. Truck Production Management System

(TPMS)33. Left side dash panel controls and

switches34. Right side dash panel controls and

switches35. Transmission shift lever36. Overhead console switches37. Brake pedals and throttle pedal38. Fuse panels39. Electronic system block diagram40. Instrument cluster

41. Instrument cluster in front dash panel42. Indicator lamps and gauges43. Messenger display module44. Main menu selection45. Performance screen submenu46. Performance menu selection47. Totals menu selections48. Settings menu selection49. Service menu selection50. Service menu diagnostic events51. Service mode52. VIMS/advisor display53. Advisor introduction screen54. Advisor main screen55. Warning screens56. Advisor operator menu57. Advisor operator profile58. Advisor home menu selections59. Advisor operator menu selection60. Service menu submenus61. Advisor calibrations screen62. Advisor service menu - Diagnostics

submenu63. Service menu - calibrations submenu64. Service menu - service parameters

submenu65. Settings menu66. Settings menu - display setup67. Payload menu option68. Payload target and calculated gauge

information69. Monitor menu option - four parameters70. Monitor: Parameter Screen 171. Grade menu option72. Grade value and truck image information73. Service mode option74. Service mode disabled option75. C32 engine with ACERT Technology76. Engine ECM system diagram77. Engine ECM78. Left intake air temperature sensor79. Crankshaft speed/timing sensor80. Cam speed/timing sensor

VISUAL LIST

Page 240: Serv1828 Txt

SERV1828 - 240 - Text Reference01/07

81. Loss of engine speed/timing signal82. Throttle position sensor83. Pre-lubrication (Quick Evac) pump84. Ether start system85. High coolant temperature derate86. C11-C32 engine intake manifold

temperature derate87. Engine exhaust manifold temperature

derate88. Low oil pressure derate89. Air inlet restriction derate90. Fuel temperature derate91. Fuel filter restriction derate 92. Engine compression brake93. Engine compression brake hydraulic

circuit - compression brake OFF94. Engine compression brake schematic95. ARC power and compression braking

levels vs time96. Jacket water cooling system97. Cooling system components98. Cooling system flow99. Engine oil system100. Fuel priming switch101. Fuel transfer pump102. Differential fuel pressure switch103. Fuel pressure regulator104. Low pressure fuel system105. Injector trim codes106. Injector trim file107. Air filter restriction indicator108. Turbocharger inlet pressure sensor109. C32 engine turbochargers110. ATAAC cores111. Exhaust temperature sensors112. Turbocharger outlet pressure sensors113. Air induction and exhaust system114. 777F power train major components115. Power train electronic components116. Power train hydraulic system117. Torque converter hydraulic system118. Power train pump sections119. Torque converter - converter drive120. Torque converter - direct drive

121. Rear of torque converter122. Torque converter screen123. Lockup clutch modulating valve - torque

converter drive124. Lockup clutch modulating valve - direct

drive125. Torque converter outlet temperature

sensor126. Lockup clutch valve oil filter127. Lockup clutch oil filter bypass switch128. Lockup clutch relief valve129. Torque converter charging filter130. Torque converter filter S•O•S port131. Transmission hydraulic system -

NEUTRAL132. Transmission scavenge pump section133. Transmission oil cooler134. Transmission charge oil filters135. Transmission modulating valves136. Transmission clutch engagement chart137. Transmission modulating valve - no

commanded signal138. Transmission modulating valve -

commanded signal below maximum139. Transmission modulating valve -

commanded signal at maximum140. Main relief valve141. Rear axle components142. Differential removed from rear axle

housing 143. Transmission/Chassis control module

system diagram144. Transmission/Chassis ECM145. Transmission shift lever circuits146. Transmission output speed sensors147. Engine speed sensor148. Transmission oil level switch149. Body up switch150. Transmission/Chassis ECM - systems

controlled by the ECM151. 777F steering system major components152. Oil level sight gauge153. Steering system oil filter154. Steering pump and control valve

VISUAL LIST

Page 241: Serv1828 Txt

SERV1828 - 241 - Text Reference01/07

155. Steering pump - low pressure standby156. Steering pump - maximum flow157. Steering disable valve158. Steering valve159. 777F HMU160. Electric secondary steering pump and

motor161. Secondary pressure switch162. Steering hydraulic system schematic-

HOLD163. 777F hoist system major components164. Hoist lever165. Hoist lever, transmission sensor, and

transmission shift lever sensor166. Hoist, converter, and brake hydraulic

tank167. Rear of hoist, converter and brake

hydraulic tank168. Hoist pump169. Hoist pump pressure tap170. Hoist control valve171. Hoist solenoid valves172. Hoist system pressure taps173. Hoist control valve - HOLD174. Hoist control valve - RAISE175. Hoist control valve - LOWER/POWER

DOWN176. Hoist control valve - FLOAT177. Hoist control valve - SNUB178. Two-stage hoist cylinders179. 777F hoist and brake cooling schematic180. Brake system major components181. Oil cooled brake assembly (cutaway)182. 777F Standard front brake183. 777F optional caliper disc brake184. Brake charging pump185. Brake oil cooling pump186. Brake system oil filter187. Brake accumulator pressure switch188. Accumulator charging valve

189. Accumulator charging valve - CUT-IN190. Accumulator charging valve - CUT-OUT191. Service brake accumulators192. Parking brake accumulator193. Cab brake manifold194. Service brake pressure switch195. Service brake pedal196. Service brake valve197. Manual retarder lever198. Rear slack adjuster199. Front slack adjuster200. Brake slack adjuster sectional view201. Service brake bleed screw202. Parking brake valve203. Parking brake solenoid valve204. Left and right parking brake tap205. Secondary brake pedal position sensor206. Brake retract pump section207. Diverter (towing) valve208. Brake cooling system - oil cooled front

brakes209. Brake cooling pump210. Brake oil coolers211. Rear brake housing212. Brake hydraulic system schematic213. Brake control module system diagram214. Brake ECM215. Service / Retarder brake circuit -

BRAKES RELEASED216. Automatic retarder control (ARC)217. Traction control system (TCS)218. Right rear wheel speed sensor219. TCS valve220. TCS valve - engine running / brakes

released221. TCS valve - engine running / left brake

engaged222. Model view - rear

VISUAL LIST

Page 242: Serv1828 Txt

HYDRAULIC SCHEMATIC COLOR CODE

This illustration identifies the meanings of the colors used in the hydraulic schematics and cross-sectional views shown throughout this presentation.

SERV1828 - 242 - Text Reference01/07

Dark Gray - Cutaway section

Light Gray - Surface color

Red - High pressure oil

Red/White Stripes - 1st pressure reduction

Red Crosshatch - 2nd reduction in pressure

Pink - 3rd reduction in pressure

Red/Pink Stripes - Secondary source oil pressure

Orange - Pilot, charge, or Torque Converter oil

Orange / White Stripes -Reduced pilot, charge, or TC oil pressure

Green - Tank, sump, or return oil Blue - Trapped oil

Brown - Lubricating oil

Purple - Pneumatic pressure

Orange Crosshatch - 2nd reduction inpilot, charge, or TC oil pressure.

White - Atmosphere orAir (No pressure)

Yellow - Moving or activated components

Cat Yellow - (Restricted usage)Identification of componentswithin a moving group

Black - Mechanical connection. Seal

Green / White Stripes -Scavenge Oil or Hydraulic Void

HYDRAULIC SCHEMATIC COLOR CODE

Page 243: Serv1828 Txt

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SERV1828 - 243 - Handout No. 101/07

Page 244: Serv1828 Txt

Machine Daily Inspection Checklist

Directions: Use this sheet and the Operation and Maintenance Manual when performing the dailyinspection as part of the machine orientation lab exercise.

Place a check in the blank after the task is performed.

_____ Back-up Alarm - Test

_____ Brake, Indicators, and Gauges - Test

_____ Braking System - Test

_____ Cooling System Level - Check

_____ Differential and Final Drive Oil - Check

_____ Engine Air Filter Service Indicator - Inspect

_____ Engine Oil Level - Check

_____ Engine Oil Level (Oil Renewal System) - Check

_____ Engine Oil Level (Oil Renewal System) - Log Additions

_____ Fuel Tank Water and Sediment - Drain

_____ Fuel System Water Separator - Drain

_____ Hoist, Converter, and Brake Tank Oil Level - Check

_____ Seat Belt - Inspect

_____ Secondary Steering - Test

_____ Steering System Oil Level - Check

_____ Transmission Tank Oil Level - Check

SERV1828 - 244 - Handout No. 201/07

Page 245: Serv1828 Txt

Machine Maintenance Locations

Place a check in the blank after locating the following maintenance items.

Filter Locations:

_____ Brake oil filter

_____ Steering pump oil filter (case drain)

_____ Steering system oil filter

_____ Transmission oil filters

_____ Torque converter charge oil filter

_____ Lockup clutch oil filter

_____ Air conditioner filter

_____ Cab air filter

_____ Engine oil filters

_____ Engine air filters

_____ Engine crankcase breather

_____ Secondary fuel filter

_____ Primary fuel filter

_____ Fuel tank breather

_____ Torque converter breather

_____ Differential and final drive breather

Sampling Valve Locations:

_____ Engine oil

_____ Hoist, converter, and brake oil

_____ Transmission oil

_____ Steering system oil

What is used to take oil samples of the differential, final drive, and front wheel?

_________________________________________________________________

SERV1828 - 245 - Handout No. 301/07

Sampling Port Locations:

_____ Differential and final drive

_____ Front wheel

Page 246: Serv1828 Txt

Instrument Cluster Component Identification

List the number of each gauge or indicator:

SERV1828 - 246 - Handout No. 401/07

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Brake system check

Power train system check

Action lamp

Electrical system

Body up

Transmission in reverse

High beam

Transmission oil temperature gauge

Secondary steering engaged

Truck speed

LCD display window

Primary steering loss

Service hour meter

Traction control system engaged

Retarder engaged

Engine coolant temperature gauge

Machine immobilizer

Throttle lock

Engine rpm

Machine lockout active

Park brake engaged

Check engine

Brake oil temperature gauge

Fuel level gauge

Active gear and direction

Page 247: Serv1828 Txt

Engine Component Identification

_____ Fuel injectors

Function:

Location:

_____ Coolant temperature sensor

Function:

Location:

_____ Fuel pressure sensor

Function:

Location:

_____ Intake manifold temperature sensors

Function:

Location:

_____ Atmospheric pressure sensor

Function:

Location:

_____ Turbo outlet (boost) pressure sensors

Function:

Location:

SERV1828 - 247 - Handout No. 501/07

Page 248: Serv1828 Txt

Engine Component Identification (continued)

_____ Engine oil pressure sensor

Function:

Location:

_____ Speed/timing sensors

Function:

Location:

_____ Engine ECM

Function:

Location:

_____ Ground level shutdown switch

Function:

Location:

_____ Secondary fuel filter

Function:

Location:

_____ Primary fuel filter

Function:

Location:

SERV1828 - 248 - Handout No. 601/07

Page 249: Serv1828 Txt

Engine Component Identification (continued)

_____ Exhaust temperature sensors

Function:

Location:

_____ Oil level switch

Function:

Location:

_____ Fuel temperature sensor

Function:

Location:

_____ Differential fuel pressure switch

Function:

Location:

_____ Engine compression brake assemblies

Function:

Location:

_____ Air filter restriction sensors

Function:

Location:

SERV1828 - 249 - Handout No. 701/07

Page 250: Serv1828 Txt

Power Train Component Identification

_____ Pump group

Function:

Location:

_____ Transmission oil filters

Function:

Location:

_____ Lockup clutch relief valve

Function:

Location:

_____ Lockup clutch oil filter

Function:

Location:

_____ Lockup clutch modulating valve

Function:

Location:

_____ Torque converter outlet relief valve

Function:

Location:

SERV1828 - 250 - Handout No. 801/07

Page 251: Serv1828 Txt

Power Train Component Identification (continued)

_____ Torque converter inlet relief valve

Function:

Location:

_____ Torque converter charge filter

Function:

Location:

_____ Torque converter outlet temperature sensor

Function:

Location:

_____ Transmission main relief valve

Function:

Location:

_____ Transmission modulating valves

Function:

Location:

_____ Transmission oil cooler

Function:

Location:

SERV1828 - 251 - Handout No. 901/07

Page 252: Serv1828 Txt

Power Train Component Identification (continued)

_____ Transmission hydraulic oil temperature sensor

Function:

Location:

_____ Transmission/Chassis ECM

Function:

Location:

_____ Engine speed sensor

Function:

Location:

_____ Torque converter oil temperature sensor

Function:

Location:

_____ Transmission input speed sensor

Function:

Location:

_____ Transmission output speed sensors

Function:

Location:

SERV1828 - 252 - Handout No. 1001/07

Page 253: Serv1828 Txt

Steering System Component Identification

_____ Steering pump

Function:

Location:

_____ Steering valve

Function:

Location:

_____ Steering disable valve

Function:

Location:

_____ HMU

Function:

Location:

_____ Steering cylinders

Function:

Location:

_____ Secondary steering pump

Function:

Location:

SERV1828 - 253 - Handout No. 1101/07

Page 254: Serv1828 Txt

Steering System Component Identification (continued)

_____ Steering tank

Function:

Location:

_____ Primary steering pressure switch

Function:

Location:

_____ Secondary steering pressure switch

Function:

Location:

SERV1828 - 254 - Handout No. 1201/07

Page 255: Serv1828 Txt

Hoist System Component Identification

_____ Hoist pump

Function:

Location:

_____ Hoist control valve

Function:

Location:

_____ Hoist, converter, and brake hydraulic tank

Function:

Location:

_____ Hoist cylinders

Function:

Location:

_____ Hoist lever position sensor

Function:

Location:

_____ Hoist raise solenoid valve

Function:

Location:

SERV1828 - 255 - Handout No. 1301/07

Page 256: Serv1828 Txt

Hoist System Component Identification (continued)

_____ Hoist lower solenoid valve

Function:

Location:

_____ Brake cooling relief valve

Function:

Location:

SERV1828 - 256 - Handout No. 1401/07

Page 257: Serv1828 Txt

Brake System Component Identification

_____ Brake charging pump

Function:

Location:

_____ Brake cooling pump

Function:

Location:

_____ Accumulator charging valve

Function:

Location:

_____ Brake accumulators

Function:

Location:

_____ Cab brake manifold

Function:

Location:

_____ Brake oil filter

Function:

Location:

SERV1828 - 257 - Handout No. 1501/07

Page 258: Serv1828 Txt

Brake System Component Identification (continued)

_____ Front slack adjuster

Function:

Location:

_____ Rear slack adjuster

Function:

Location:

_____ Service brake valve

Function:

Location:

_____ Retarder lever

Function:

Location:

_____ Parking brake valve

Function:

Location:

_____ TCS valve

Function:

Location:

SERV1828 - 258 - Handout No. 1601/07

Page 259: Serv1828 Txt

Brake System Component Identification (continued)

_____ Service brake pedal position sensor

Function:

Location:

_____ Secondary brake pedal position sensor

Function:

Location:

_____ Brake retract pump

Function:

Location:

_____ Diverter (towing) valve

Function:

Location:

_____ Brake oil coolers

Function:

Location:

_____ Brake ECM

Function:

Location:

SERV1828 - 259 - Handout No. 1701/07

Page 260: Serv1828 Txt

Brake System Component Identification (continued)

_____ Accumulator oil pressure switch

Function:

Location:

_____ TCS test switch

Function:

Location:

_____ ARC switch

Function:

Location:

_____ Brake compression switch

Function:

Location:

_____ Front brake lockout switch

Function:

Location:

_____ Rear wheel speed sensors

Function:

Location:

SERV1828 - 260 - Handout No. 1801/07

Page 261: Serv1828 Txt

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SERV1828 - 261 - Handout No. 1901/07

Page 262: Serv1828 Txt

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SERV1828 - 262 - Handout No. 2001/07

Page 263: Serv1828 Txt

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SERV1828 - 263 - Handout No. 2101/07

Page 264: Serv1828 Txt

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SERV1828 - 264 - Handout No. 2201/07

Page 265: Serv1828 Txt

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Page 266: Serv1828 Txt

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SERV1828 - 266 - Handout No. 2401/07

Page 267: Serv1828 Txt

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SERV1828 - 267 - Handout No. 2501/07

Page 268: Serv1828 Txt

Posttest1. When the engine lockout mode is activated, which of the following conditions exist:

A. engine starter is disabledB. secondary steering is disabledC. prelube function is disabledD. All of the above

2. The air conditioner filter is located:

A. on the left side of the cabB. on the right side of the cabC. on the front of the cabD. on the rear of the cab

3. The monitoring system includes how many warning categories

A. 2B. 3C. 4D. 5

4. How many main menus are available for navigation on the Messenger menu screen?

A. 3B. 4C. 5D. 6

5. Which of the following Messenger menus is used to determine when scheduled maintenance isrequired?

A. Performance menuB. Totals menuC. Settings menuD. Service menu

6. What information is NOT displayed when viewing diagnostic events on the Messenger displaypanel?

A. SRC (Source ID)B. CodeC. OCC (number of occurrences)D. Parameter

SERV1828 - 268 - Handout No. 2601/07

Page 269: Serv1828 Txt

Posttest (continued)7. When a "pop-up" warning screen is displayed on the Advisor display, which of the following is

true?

A. Acknowledging the warning will clear the warning from the ECM's memoryB. Acknowledging the warning will only clear the warning from the Advisor screenC. If the warning is acknowledged the warning no longer remains activeD. None of the above

8. The calibrations menu in the Advisor Monitoring System allows calibration of which of thefollowing:

A. truck payloadB. injectorsC. pressure sensorsD. hoist solenoid valve

9. The monitor menu option in the Advisor Monitoring System allows the user to view how manyparameters at one time?

A. 1B. 2C. 3D. 4

10. Each compression brake assembly controls how many cylinders?

A. 1B. 2C. 3D. 4

11. When the Engine ECM commands a MEDIUM braking level, the compression brake is activatedfor how many cylinders?

A. 4B. 6C. 8D. 12

12. Pilot oil used to actuate the hoist solenoid valves is supplied by the:

A. lockup clutch valve oil circuitB. parking brake release filterC. hoist pumpD. pressure reducing valve

SERV1828 - 269 - Handout No. 2701/07

Page 270: Serv1828 Txt

Posttest (continued)13. The lockup clutch relief valve allows oil to flow to the _______________ when the lockup clutch

valve circuit oil pressure is too high?

A. transmission hydraulic tankB. hoist, converter, and brake hydraulic tankC. steering circuitD. brake cooling circuit

14. Which of the following components is located on top of the transmission planetary gears?

A. Transmission main relief valveB. Transmission modulating valvesC. Transmission hydraulic oil temperature sensorD. All of the above

15. Which of the following sensors checks the speed of the drive shaft to the speed of the engine?

A. Engine speed sensorB. Transmission input speed sensorC. Transmission output speed sensorsD. Torque converter output speed sensor

16. When the machine lockout switch is activated, which of the following actions occurs?

A. HMU oil flow is blockedB. Steering pump is disabledC. Steering disable solenoid valve is energizedD. All of the above

17. Which of the following is not installed on trucks with the optional caliper type front brakes?

A. Brake cooling pumpB. Brake oil coolersC. Brake cooling relief valveD. All of the above

18. The ARC system uses the rear service brakes and the ______________________ to automaticallycontrol truck speed.

A. TCSB. parking brakesC. front caliper type brakesD. front oil cooled brakes

SERV1828 - 270 - Handout No. 2801/07

Page 271: Serv1828 Txt

Posttest (continued)19. The front service brake solenoid directs oil to the front service brakes. What component directs

oil to the rear service brakes?

A. Service brake valveB. ARC solenoidC. Diverter valveD. Both A and B

20. Oil is provided to the diverter valve by the:

A. brake cooling pumpB. service brake accumulatorsC. parking brake accumulatorD. hoist pump

SERV1828 - 271 - Handout No. 2901/07

Page 272: Serv1828 Txt

Posttest Answer Key1. D2. A3. C4. C5. B6. D7. B8. A9. D

10. B11. C12. A13. D14. D15. B16. C17. A18. D19. D20. C

SERV1828 - 272 - Handout No. 3001/07


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