02 Transmission System LG958L

LG958L Training material

RELIABILITY IN ACTION1

Tuesday, May 19, 2015

Chapter IV ZF Transmission

Structure and Principle of Torque Converter

CONTENTS

Structure and Principle of Transmission

Oil Supply and Lubrication System of ZF Transmission

Electric Control System of ZF Transmission


Operation and Maintenance of ZF Transmission

Common Malfunctions and Troubleshooting of ZF

Transmission

1Section I Structure and Principle of Torque Converter


Figure 4-1 Diagram of Transmission System for LG958L Loader 1. Torque converter 2. Rear drive axle 3. Transmission 4. Drive shaft 5. Front drive axle

32 4 5

The hydraulic torque converter is installed between the engine and transmissionand is mainly function to change the torque outputted by the engine so that thetorque output of the turbine will probably exceed the input torque of engine viapump impellor so as to improve the power performance of loader and ensure thestable transmission.


Figure 4-2 Internal Structure Diagram of ZF Torque Converter Torque converter: It’s mainly composed of pump impellor, turbine, idler pulley(commonly referred to as three-element part.), and housing and it’s capable ofautomatically regulating the torque output and speed output of the engine.

Working principle of torque converter: Some blades are uniformly arranged within each working

Pump impellorGuide pulley

Turbine


Working principle of torque converter: Some blades are uniformly arranged within each workingimpellor of the torque converter. These blades work together with each other to form anenclosed annular space, in which the fluid can recirculate. When the engine flywheel drives therotation of pump impellor, the blades of the pump impellor drives the rotation of fluid. Under theaction of the centrifugal force, the fluid flows from the inner edges of blades to the outer edgesto impact the turbine blades and drive the rotation of turbine for torque output. The flowing fluidflows from the outer edges of blades to the inner edges of blades within the turbine to impactthe blades of guide pulley and then returns to the pump impellor along the blades of guidepulley for next cycle. The torque conversion of the hydraulic torque converter is attributed to thepresence of guide pulley. The guide pulley is connected with the torque converter housing viafixed guide pulley seat and the torque converter is connected with engine flywheel via elasticplate.

1. Characteristics of ZF transmission: 4 forward gears and 3 reverse gears High working efficiency Low repair rate Ultra-long service life Low fuel consumption Low noise

Section II Structure and Principle of Transmission


Structural diagram of ZF transmission

Connecting flange with torque converter and engine ZF transmission Torque converter

2. Structure of ZFtransmission

The ZF transmission ismainly composed ofelectronic control units(gearshift operatinglever, electric controlbox, and gearshiftZF


box, and gearshiftvalve) and mechanicalgearshift transmission(6 clutches and drivegears and outputshaft).

ZF transmission Transmission ZF transmission Gearshift operating lever

ZF transmission

Rear view of transmission

Oil filter 1st power takeoff port

Output speed Optional emergency pump portClutch K1Clutch KV

Clutch KR

2nd power takeoff port 1st power takeoff port


Output speed sensor Transmission filler port Output flange, fitted with parking brake

Clutch K2Clutch K3Clutch K4

Clutch KVRemoved part on right side of transmission

Press once KD button


Use of KD button function of ZF transmission in actual applications

Electric control box of ZF transmission

Gearshift valve of ZF transmission (including pressure measuring point)

Clutch K3Two-stage pressure control valve 1Mpa reducing valve

M4 Oil pipe to two-stage pressure pilot control valve


Solenoid valve (resistance: 90±10Ohm) During electric welding of main unit for repair, unplug the connector of electric control box Forward clutch KVReverse clutch KR K4 clutchClutch K2System pressure Clutch K1

Clutch KV

Clutch K1


Clutch KV and K1 of ZF transmission

Power drive gear

Schematic diagram of clutch


Clutch KV and K1 of ZF transmission


Clutch KR and K2 of ZF transmission


Clutch K3 and K4 of ZF transmission


The travel for pistons of various clutches is 1.8~2.4mm.


The axial clearance is 0.1~0.3mm after assembly of various shafts.

Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears) Internal structural diagram of ZF transmission

3. Route diagram for various gears of ZF transmission

1st forward gear Output


Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears)

3rd forward gear

2nd forward gear

OutputOutput



4th forward gear

1st

reverse gear

OutputOutputCountershaft



2nd reverse gear

3rd reverse gear OutputOutput


Section III Oil Supply and Lubrication System of ZF Transmission


Oil recirculation schematic diagram of transmission with two-stage pressure control valve


Cast aluminum gearshift control valve with 5 solenoid valves and two-stage pressure control valve

Section IV Electric Control System of ZF Transmission 1. ZF built-in electric system

1. Electric control box EST-17T

2. Transmission3. Gearshift


3. Gearshift operating lever DW-2

4. Connecting port to circuits of complete machine

5. To transmission solenoid valve

6. To output speed sensor

2. ZF built-in harnesses and connectors Cable electric control box connector

Complete machine wire connector

Gearshift operating lever connector Sensor 2Sensor 1Lever 5

YellowGreenPink

PurpleBlue

BlackRedGrey

(I)


Complete machine wire connector Solenoid valve connector

Starter interlocker 584Pressure switch 600 Lever 8Lever 6

Lever 2Lever 7Lever 9Lever 10Lever 4Sensor 1Pink

3. ZF peripheral electric system To electric control boxIntermediate relay(power cutoff) Intermediate relay(reversing) Intermediate relay(starter interlocker)


To instrument panel electric control box working indicator Parking brake indicator switch

Brake switch (left) Brake switch (right) To brake lamp

To starter relay signal terminal To brake lampTo starter relay terminal G2

Neutral start interlockingfunction

Neutral locking function.Rotate the red neutralgear locking switch.

Power cutoff functionduring braking at 1st gear

Lock direction

KD button

4. Gear selectorThe gear selector is the gear signal input device of the ECU. Its normalfunctioning directly influences the normal functioning of the system. Usethe multimeter for measurement and judgment.


Power cutoff functionduring braking at 1st gearor 2nd gear.

Kick-down function (KDbutton)

Gearshift operating lever of ZF transmission

Neutral gear locking switch

• The continuity and logic relationships between the red wire in the harness of gear selector and other wires and various gears are as below:

With red FI F2 F3 F4 R1 R2 R3

Blue √ × × √ √ × ×

Green × × √ √ × × √

Black √ √ √ √ √ √ √

Yellow √ √ √ √ × × ×


Yellow √ √ √ √ × × ×

Grey × × × × × × ×

Pink × × × × √ √ √

Purple × × × × × × ×

If the grey wire is under continuity state, the complete machine can’t be started. The purple is the KD function, the pink is the control of reverse gear, and the yellow is the forward gear.

5. Electric control box• As the main control part for judgment of gear, the electric control box analyzes the

signal of selector and issues command to the solenoid valve.



6. Gearshift valve The gearshift valve is the actuator unit that engages and disengages thecontrol gear of the solenoid valve as per the command of ECU.


1) Sequence of solenoid valve: 4, 3, 5, 2, and 1 from top to bottom.2) If the O-ring is not properly seated, it will easily cause oil leakage atside cap.

3) The resistance of solenoid valve is 90±10Ω.


Clutch forvarious gears KV K1 K2 K3 K4 KRControl

solenoid valve M3 M2 and M4 M4 \ M5 M1

7. Speed sensor

Transmission speed sensor


• Resistance of speed sensor:1020±100Ω

1. Operation Precautions(1) To check the transmission oil level, the engine shall idle run (at approximate

1,000r/min) and the oil temperature shall be at normal working temperature.(2) When the oil temperature is at 40ºC, the oil level shall be between the middle

mark and lower mark of the oil dipstick.When the oil temperature is at 80ºC, the oil level shall be between the middlemark and upper mark of the oil dipstick.

Section V Operation and Maintenance of ZF Transmission

Hot oil level zone


(3) Periodically replace the transmission oil and replace the filter strictly as per themaintenance schedule.

(4) Before starting the engine, ensure that the operating lever is at neutral gear.(5) Before starting up the machine each time, release the parking brake.

Cold oil level zone

(6) When it's necessary to hoist the transmission to fit the engine with transmission orseparate the engine from the transmission, avoid the fall-off of the torque converter.

(7) While parking the machine, the gearshift operating lever shall be at neutral gear.(8) The normal working oil temperature shall be within 80~110ºC. Under heavy load, the oil

temperature is allowed to rise to 120ºC for a short time. Pay special attention to thecontrolling oil pressure of the transmission. Upon detection of any abnormality in thetransmission during operation, immediately stop the machine for checking.

(9) When the electric welding is required for repair in event of the machine malfunction, makesure to disconnect the cable connector from the EST – electronic control unit (to cut offthe current to the electronic control unit), or the impact current during the electricwelding will probably burn out the electronic control unit.


2. Operations(1) Preparations and maintenance before driving• Before the operation of the transmission, make sure to add anappropriate amount of lubricating oil as per the specified specificationof lubricating oil. While adding oil to the transmission for the firsttime, make sure to take into consideration that the oil radiator, filter,and connecting pipeline must be fully filled with oil. Therefore, thelubricating oil amount to be added for the first time will be muchmore than the lubricating oil amount to be added during normalmaintenances.


• The oil level can be checked only when the operating level is atneutral gear. While checking the oil level, insert the oil dipstick to thedead end of the dipstick tube. While cleaning the filter of main oil line,pay attention to prevent the ingress of dirt and sediments into the oilcircuit. Therefore, place a cover plate to guard the parking brakeagainst being dipped by the oil.

• While installing the filter, pay attention not to tighten excessively.

(2) Driving and gearshift• To start the engine, make sure that the gearshift operating lever is at neutral gear.

For the purpose of safety, before starting the engine, the parking brake shall beunder braked state to prevent the startup of machine due to the start of engine. Afterthe engine is started, release the parking brake, select the driving direction and gear,and depress the throttle slowly to start up the machine. During the traveling of themachine, the torque converter substitutes the function of main clutch. When the roadcondition is good, it‘s possible to travel at higher gear.

• If the machine stops traveling, but the engine is still running and the transmission isshifted to a gear other than neutral gear, the engine will not stop at that time. On astraight road, the machine will probably crawl, as the idling of engine will generate acertain traction force via the torque converter. The appropriate method is to placethe parking brake at braked state whenever the machine is parked.


the parking brake at braked state whenever the machine is parked.• To park the machine for a long period, make sure to shift the operating lever to

neutral gear. During the traveling of the machine, make sure to release the parkingbrake. Due to the influence of the torque converter, while shifting from a high speedgear to a low speed gear, the engine speed will increase, especially at the time ofgear jump. Therefore, whenever the condition permits, while shifting from a highspeed gear to a low speed gear, depress the foot brake for slow deceleration beforethe gearshift. When the machine is traveling at high speed or changing drivingdirection, lower the engine speed.

(3) Driving and gearshift

• The maximum oil temperature at outlet of torque converter shall not exceed 120ºC.For non-malfunctioned control subassembly and transmission with sufficienttraveling mileage, the temperature shall not be too high. If the oil temperatureexceeds 120ºC, make sure to stop the machine and check for presence of externaloil leakage. At the same time, shift the transmission to neutral gear and run theengine at 1,200~1,500rpm. In such case, the oil temperature will lower rapidly tothe normal value (approximate within 2~3min). If the oil temperature fails to drop,certain portion within the system is malfunctioned. Make sure to resolve themalfunction before proceeding the operations.

• Normal range for gearshift oil pressure: 1.6~1.8MPa (16~18bar). To monitor the


• Normal range for gearshift oil pressure: 1.6~1.8MPa (16~18bar). To monitor thecontrol pressure, make sure to install a pressure gauge or pressure monitoringunit. If the pressure drops to below the specified minimum pressure after a certaingear is engaged and the clutch is depressed (though the pressure at moment ofgearshift will drop automatically temporarily), make sure to resolve the cause ofpressure drop. The under-low control pressure will lead to damage of clutch, as theclutch is short of sufficient contact pressure and the continual skid of friction plateleads to over-heating.

3. Maintenance

(1) Check the oil level.

- Park the machine on a level place.

- Shift the gearshift operating lever of the transmission to neutral gear “N” andset the parking brake at braked position.

- Idle run the engine at approximate 1,000r/min.

- Counterclockwise the oil dipstick and take out and wipe clean the oil dipstick.

- Insert the oil dipstick into the oil dipstick tube and tighten to place. Wait for 3sand take it out (measure for at least two times).

- When the oil temperature is at 40ºC, the oil level shall be between the middle



mark and lower mark "Cold” of the oil dipstick.


mark and upper mark "Hot” of the oil dipstick.

Caution: Checking the oil level under cold state is to ensure sufficientrecirculation flow for transmission and torque converter and the decisive criterion

for oil level is to meet the oil level requirement under hot state.

•

(2) Replace the oil.Make sure to replace the oil for the first time after the machine is workingfor the first 100 hours. Afterwards, replace the oil once every 1,000 workinghours or once a year. At the replacement of oil, park the vehicle at a levelplace. Under the working temperature of the transmission, take out the oildrainage plug and seal ring and fully drain the used oil.- Start the engine and idle run the engine.- Shift the transmission operating lever to neutral gear “N”.- Add oil to the upper mark of the oil range “Cold”.- Set the parking brake at safe place.- Shift to every gear for once.


- Shift to every gear for once.- Check the oil level and when necessary add the oil.

Part Name Initial oil replacement

Normal oil replacement Oil specification Checking of oil

level

Transmission(4WG200)

After 100 working hours. Replace filter

as well.

At interval of 1,000 working hours, but no

more than 1 year. Replace filter as

well.

Mobil Delvac 1300 SAEl5W40 or Titan

universal oil HD15W-40 (manufactured by

Shanghai Desi Oils Co., Ltd.)

Before operation each

day

(3) Replace oil filter.Make sure to replace ZF fine filter at the replacement of oileach time. Replace as per the following requirements:

- Apply a thin film of oil onto the seal ring.- Push in the filter, till it comes into contact with the sealing

surface on the transmission, and then tighten for approximate1/3~1/2 turn with hand.

- Add oil.- Start the engine.


- Start the engine.- Idle run the engine (at approximate 1,000r/min). When the

transmission oil temperature reaches working temperature,check the transmission oil level.

- Check whether the filter is tightened. If necessary, tighten againwith hand.

(4) Assembly precautions for ZF transmission:I. Fitting and connection between ZF transmission and engine

1. Wipe clean the anti-rusting oil from the engine flywheel and the inside offlywheel housing to be fitted.

2. Place the transmission at the fitting station and disassemble the fixing woodplate from the torque converter middle flange on the transmission (It'sabsolutely prohibited to slide outward the torque converter and its middleflange).

3. While fitting and connecting the transmission with engine, without moving thetransmission, fit the flywheel housing of engine with the torque converterconnecting housing on the transmission and ensure that the middle flange oftorque converter enters into the junction surface of the engine flywheel.


torque converter enters into the junction surface of the engine flywheel.

Fall-off of torque converter

4. Completely fit and fix the connecting housing of torque converter andflywheel housing of engine with three bolts and then tighten the connectingbolts of torque converter middle flange and engine flywheel in turn.

5. Finally tighten all connecting bolts of torque converter connecting flange andengine flywheel housing.

6. Through the square observation port on the connecting housing of thetorque converter, check the connecting elastic plate between torqueconverter and its middle flange for presence of squeezed deformation(Under normal status, the plane of elastic plate shall be perpendicular to theaxis of middle flange).

7. Control size for connecting the connecting housing of transmission withengine flywheel housing: 39.6±0.5.


engine flywheel housing: 39.6±0.5.II. Precautions for installation from transmission and radiator oil pipeThe tightening depth for the connection between pipe connector andtransmission shall not come into contact with the core of the backpressure valve.If the insertion depth exceeds 21mm, it will cause working failure of thebackpressure valve due to blockage of core and obstruct the recirculation oil linebetween transmission torque converter and radiator so that the working oil of thetorque converter can’t be sufficiently recirculated for heat radiation to causeover-high oil temperature of the torque converter.

III. Installation of torque converter temperature sensor

1. While installing the temperature sensor at the oil temperature measuringpoint of the torque converter, upon detection that the top of the sensor is

pushed against the core of backpressure valve, do not forcibly screw in the

sensor. Please timely notify the technician to solve the malfunction, in orderto prevent the damage of sensor and valve core due to interference.

IV. Fluid within side cap of gearshift operating valve

1. After the engine is started, a part of oil in the gearshift operating oil system

will overflow and return to the tank via the oil line within the side cap of the


will overflow and return to the tank via the oil line within the side cap of thegearshift operating valve. Therefore, when the side cap is opened during the

running of the engine, the oil will spray from the valve body. Therefore, while

installing the side cap, make sure properly seat the O-ring of side cap and

clamp the hoop to the required place, in order to prevent the so-called valveleakage symptom.

2. Do not open the side cap of gearshift operating valve at will.

V. Speed sensor1. The gap between the end of speed sensor and the tooth top of gear is

0.5~0.8mm. The disassembly of sensor without prior consent and theincorrect installation will lead to damage of the sensor.Do not disassemble the speed sensor without prior consent.

2. The service personnel is disallowed to add or remove the adjustmentwasher at the time of assembly.

Speed sensor


VI. ZF cables1. While arranging the cables, ensure that the cables at all positions

are free of friction with any other part.2. The cables at all positions shall be correctly fixed.

VII. Electric control box1. At the time of electric welding, unplug the connector of electric

control box to disconnect the electric control box from circuits andprevent the burnout of electric control box.


prevent the burnout of electric control box.2. Guard the electric control box against moisture and rainfall.

Section VI Cause Judgment and Troubleshooting for Common Malfunctions of ZF Transmission

1. No gear, though the complete machine can be started. Check oil level Check the cable for presence of worn damage. Check the connectors and fuses Check whether the power voltage is at a stable normal value. Check the parking brake for normal functioning.


Check the parking brake for normal functioning. Check for normal power connection between engine and torque

converter. Check for normal gearshift oil pressure. Check for normal functioning of gearshift operating lever. Check for normal functioning of solenoid valve.

2. No 3rd gear or 4th gear is available, though the 1st gear and2nd gears are available in complete machine.

» Check oil level» Check cable connectors for normal connections.» Check cables for worn damage.» Check speed sensor for normal functioning.» Check lever for normal functioning.


3. No 1st gear or 2nd gear is available, though the 3rd gear and4th gears are available in complete machine.

» Check the cables for normal connection.» Check pressure sensor for normal functioning.

4. Noise of transmission » Check oil level» Check the connecting bolts between transmission and frame

and engine for presence of looseness. » Check the drive shaft and its support for normal functioning. » Check the hydraulic pump for abnormality. » Check the articulations for normal functioning. 5. Weak complete machine


5. Weak complete machine » Check oil level» Check whether the gearshift pressure is at 1.6~1.8MPa. » Check for normal power of engine. » Check the oil for improper trademark, deterioration, and

presence of air bubble.

THE ENDTHE ENDTHE ENDTHE END


02 Transmission System LG958L

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