Railway Projct

INTRODUCTION

INDIAN RAILWAYS

Indian railways is the second largest networking the world. Indian railways has a fleet of about 3800 BG Diesel locomotives Which are based in about 47 maintenance sheds spread all over the country.

WHAT IS DIESEL SHED

It is a place where repair and maintenance work of diesel locomotives Is carried out so as to increases its life and efficiency and to reduce line failures to a minimum extent.

DIESEL SHED AT TUGHLAKABAD, DELHI

Tughlakabad is one such premier shed in Northern Railways homing 162 Diesel Locos. Because of its geographical location ,and being In the capital, it serves a large number of Mails /Express trains which across the length & breadth of the country casting to goods operation.

Diesel Shed, Tughlakabad is spread over an area of 1,10,000 m 2 out of Which 10,858 m2 is covered.

Diesel Shed ,Tughlakabad was established in the year 1970 with a planned holding of 75 locomotives and initial holding of 26 WDM2 locomotives.

Today, after 40 years of its existence, the shed has grown to a total holding of 162 locomotives of five types, which include 59WDM2

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(2600HP) 21 WDM4 (3100HP) 02 WDM2 (3300HP), 51 WDP1 (2300HP) and 29WDP3 (3100HP).

Shed is maintain a mail link of 122 locos, which is highest for any shed on Indian railways. Some of the important and prestigious trains being run by the shed are : Jammu Tawi and Guhati Rajdhani express, Shatabdi express for Amritsar ,Dehradun and Ajmer, Puja Express, Uttar Sampark kranti, Lucknow Mail, Kashivishwanath, Sharamjivi Express and the tourist train palace-on-wheels.

SHED LAYOUT & INFRASTRUCTURE

The shed has a total berthing capacity for 17 locomotives under 4 covered bays. The main bays are:-

1. The subassemblies section 2. The heavy repair and bogie section(3 berths for heavy

repairs & 2 lifting points)3. Mail running repair bay(6 berths).4. Goods and out of course running repair bay(6 berths)

There is one old steam shed, which has recently been connected. This shed has a capacity for berthing 4 locomotives and is not equipped with lighting and overhead crane. This shed can hence be used for light repairs only.

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DIESEL TRAINING CENTRE

Diesel training centre at Tughlakabad was set in 1975 in premises of diesel shed, Tughlakabad northern railway with a view to train diesel running staff as well as diesel maintenance to improve overall efficiency of railway workers quality by upgrading the knowledge of railway workmen by starting few courses.

INFRASTUCTURE

DIESEL TRAINING CENTRE

There are five classrooms ,a big hall and a model room with cut models (with working and non-working types of various important components of locomotives such as expressor,cylinder head, turbo super charger, water pump, lube oil pump, governor, etc for better understanding. A well qualified team of trainers from maintenance and running is available for providing training.

DIESEL FAULT SIMULATOR

It comprises of actual electric panel, cut model of engine block(in working) and test benches. It helps n improving, analyzing and understanding trouble-shooting knowledge of running staff as well as maintenance staff

REGULAR COURSES

1. Diesel Asstt. to diesel driver promotion course2. Diesel Asstt. Refresher course3. Diesel refresher course

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OTHER SPECIAL COURSES

1. Knowledge up gradation shot duration course for Dsl. Tech. (Mech. & Elect)

2. Electric traction to diesel traction conversion.3. Course for drivers, shutters & Asstt. Drivers.4. 3 years Apprentice tech. (Dsl) – (Mech. & Elect.)5. 6 months Apprentice Tech. (Dsl) (Mech.- RRB Batch).6. Preselections couching of SC/ST candidates for group

‘B’ LDCE cadre.7. Preselection coaching of SC/ST candidates of

Technicians for the post of JE-28. Preselection coaching of SC/ST candidates of Dsl.

Technicians for the post Asstt. Drivers.

ORGAISATIONAL STRUCTURE AND STAFF STRENGTH

Tughlakabad has a sanctioned strength of 1313 against which 1210 persons are on roll. There are 9 posts of officer in the shed. The shed is headed by the Sr. DME who is assisted by 2 Sr. scale & 6 Jr. scale officers.

The laboratories is looked after by an ACMT and the attached stores depot by an AMM. The training school & simulator center have been entrusted to a separate Assistant Officer. These officer also report to the Sr. DME.

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SUMMARY OF TECHNICAL STAFF OF DIESEL SHED TUGHLAKABAD

S.No. Section Name

Strength S.No.

1. Air point 01 22.2. Air Brake 34 28.

3. Gauge 04 29.4. Battery 09 30.

5. Bogie 69 31.6. Canteen 18 32.

7. Carpenter 04 33.8. Control

room23 34.

9. CTA 04 35.10. Cylinder

head21 36.

11. Drawing 02 37.12. Diesel

assistant08 38.

13. Diesel trng school

03 39.

14. Elect/goods 75 40.15. Elect/Mail 58 41.16. Elect/Yearly 55 42.

17. Expressor 35 43.18. F.I.P. 05 44.19. Fuel section 17 45.

20. Gasket 05 46.

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room21. Half

yearly/Mech08 47.

22. Diesel hostel

15 48.

23. Laboratory 14 49.24. Loco cabin 05 50.

25. Loco turn out

02 51.

26. Machine shop

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CLASSIFICATION OF LOCOMOTIVES

Q. What do the designations such as WDM-2 means?

Locos, except of older steam ones, have classification codes that identify them. This code is the form ‘[gauge][power][load][series][subtype][suffix]’.

1. In this the first item, ‘[gauge]’, is a single letter identifying the gauge the locos runs on:

W = Broad Gauge(1.67m) Y = Meter Gauge (1m) Z = Narrow Gauge (2’6” or 0.762m) N = Narrow Gauge (2’ or 0.61m)2. The second item, ‘[power]’ is one or two letters

identifying the power source: D = Diesel C = DC traction A = AC traction

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CA = Dual-power AC/DC traction3. The third item,’[load]’ is a single letter identifying the

kind of load the loco is normally used for: M = Mixed Traffic P = Passenger G = Goods S = Shunting U = Multiple unit (EMU/DEMU)4. The fourth item, ‘[series]’, is a digit identifying the

horse power range of the loco, with ‘3’ for locos with over 3000hp but less than 4000hp, ‘5’ for locos over 5000hp but less than 6000hp,etc. This new scheme was applied to all passenger/goods/mixed-haul diesel locos in June2002, except for the WDM-2 and WDP-1 classes of locos.

5. The fifth item,’[subtype]’, is an optional letter or number (or to of them) that further refines the horse power indication in 100hp increments: ‘A’ for 100hp, ‘B’ for 200hp, ‘C’ for 300hp, etc. So in this scheme , a WDM-3A refers to a 3100hp loco, while a WDM-3F would be a to a 3100hp loco, while a WDM-3F would be a 3600hp loco.

6. The last item, ‘[suffix]’, is an optional indication that indicates something special about the loco, such as a different gearing ratio or brake system usual.

LOCOMOTIVES AT TKD. DIESEL SHED

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WDM2 - 2600 HP WDP1 - 2300 HP WDP3A - 3100 HP WDM3A - 3100 HP WDM3C - 3300 HP

SCHEDULES

For the proper functioning of diesel shed and to reduce the number of failures of diesel locos, there is a fixed plan for every loco, at the end of which the loco is checked and repaired. This process is called scheduling. There are two types of schedules which are as follows:-

1. Major schedules2. Minor schedules

MINOR SCHEDULES

Schedule is done by the technicians when the loco enters the shed.

After 15 days there is a minor schedule. The following steps are done every minor schedule & known as SUPER CHECKING.

The lube oil level & pressure in the sump is checked.

1. The coolant water level & pressure in the reservoir is checked.

2. The joints of pipes & fittings are checked for leakage.3. The check super charger, compressor &its working.4. The engine is checked thoroughly for the abnormal

sounds if there is any.

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5. F.I.P. is checked properly by adjusting different rack movements.

This process should be done nearly four hour only. After this the engine is sent in the mail/goods running repairs by for repairs. There are following types of minor schedules:-

1. T-1 SHEDULE AFTER 15 DAYS2. T-2 SHEDULE AFTER 30 DAYS3. T-1 SHEDULE AFTER 45 DAYS4. M-2 SHEDULE AFTER 60 DAYS5. T-1 SHEDULE AFTER 75 DAYS6. T-2 SHEDULE AFTER 90 DAYS7. T-1 SHEDULE AFTER 105 DAYS 8. M-4 SHEDULE AFTER 120 DAYS9. M-8 SHEDULE AFTER 135 DAYS

TESTING-1

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1. Fuel oil & lube check.2. Expressor discharge valve.3. Flexible coupling’s bubbles.4. Turbo run down test.5. Super checking.

TESTING-2

1. All the valves of the expressor are checked.2. Primary and secondary fuel oil filters are checked.3. Turbo super charger are checked.4. Under frame are checked.5. Lube oil of under frame checked.

MONTHLY-2 SEHEDULE

1. All the works done in T-2 sehedule.

2. All cylinder head valve loch check.

3. Sump examination.

4. Main bearing temperature checked.

5. Expressor valve checked.

6. Wick pad changed.

7. Lube oil filter changed.

8. Strainer cleaned.

9. Expressor oil changed.

MAJOR SCHEDULES

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MONTHLY-4 SCHEDULE

1. Injector changed.2. Taped facing blowing.3. Chang of total lube oil.

VARIOUS SECTION IN THE SHED

The whole shed is divided into various sections depending upon the Type of work. These section assist in the repair are maintenance work of the locos.

These assisting sections may be divided into two main groups:-

1. Directly assisting sections.2. Indirectly assisting sections.

DIRECTLY ASSISTING SECTIONS:-

These sections which directly assist in the maintenance work of the loco are called Directly assisting sections. These sections play an important role in the maintenance work. The Directly assisting sections are as follows:-

1. Turbo super charger section.2. Expresser section.3. Bogie section.4. Cylinder head section.5. Power pack section.6. Speedometer section.7. F.I.P section.8. Air brake section.9. Fuel section.

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10. Pit wheel lathe section.11. Traction motor and generator section.

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THE BRIEF INTRODUCTION OF THESE SECTIONS IS GIVEN BELOW:-

1. TURBO SUPER CHARGER SECTION

PRINCIPLE

The amount of power obtained from a cylinder in a diesel engine depends on how much fuel can be burnt in it. The amount of fuel which can be burnt depends on the amount of air available in the cylinder. So, if you can get more air into the cylinder, more fuel will be burnt and you will get more power out of your ignition. Turbo charging is used to increase the amount of air pushed into each cylinder. The turbo charger is driven by exhaust gas from the engine. This gas drives a fan which, in turn, drives a small

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compressor which pushes the additional air into the cylinder. Turbo charging gives a 50% increase in engine power.

The main advantage of the turbo charger is that it gives more power with no increase in fuel costs because it uses exhaust drive power. it does need additional maintenance, however, so there are some types of lower power locomotives which are built without it. The main working of this section is to maintain the supercharger. The different types of supercharger used in TKD diesel shed are as follows:-

1. ALCO Turbocharger(Capacity of 1.2-1.5kg/cm2)2. A.B.B Turbocharger(Capacity of 1.2-2.0 kg/cm2)3. G.E. Turbocharger(Capacity of 1.2-2.30 kg/cm2)4. STANO SUJA (MEKA) Turbocharger5. NAPIER Turbocharger

The difference between them is based on cooling system used & power required. STANO SUJA & NAPIER are air-cooled and other are water-cooled

. HOW IT WORKS

The turbocharger is bolted to the exhaust manifold of the engine. The exhaust from the cylinder spins the turbine, which works like a gas turbine engine. The turbine is connected by a shaft of the compressor, which is located between the air filter and the intake manifold. The compressor pressurizes the air going into the pistons.

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2. EXPRESSOR (6CD,4UC COMPRESSOR EXHAUSTER)

WORKING OF EXPRESSOR

The Expressor is located at the free end of the engine bloke and driven through the extension shaft attached to the engine crankshaft. Expressor is a combined unit of exhauster and compressor. The main function of exhauster unit is to create vacuum 22” in train pipe. Air from vacuum train pipe is drawn into the exhauster cylinders through the inlet valves during its suction stroke and that air is thrown out to atmosphere during compression stroke through discharge valves.

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The main function of compressor unit is to create air pressure in main reservoir of locomotive up to 10kg/cm2. Atmosphere air is drown into the compressor LP cylinder through the open inlet valves during suction stroke and same air is discharged to HP cylinder through discharge and delivery pipe. The HP cylinder compresses the air at high pressure and discharge it in main reservoir of locomotive for the use of brake system.

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BOGIE SECTION

This is the part (called the bogie) carrying the wheels and traction motors of the locomotive. A pair of train wheels is rigidly fixed to an axle to form a wheel set. Normally, if two wheel sets are mounted in a bogie it is known as BO-BO type, but if three wheel sets are mounted on truck, it is called as CO-CO type. Most bogies have rigid frames as shown below.

The bogie frame is turned into the curve by the leading wheel set as it is guided by the rails. However, there is a degree of slip and a lot of force required to allow the change of direction. The bogie carries about half the weight of the vehicle it supports. It also guides the vehicle, sometimes at high speed, into a curve against its natural tendency to travel in a straight line. They provide the propulsion, the suspensions and the braking. As you can imagine, they are tremendous structures.

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The trucks also provide the suspension for the locomotive. The weight of the locomotive rests on a big, round bearing which allows the trucks to pivot so the train can make a turn. Below the pivot is a huge leaf spring that rests on a platform. The platform is suspended by four, giant metal links, which connect to the boogie assembly. These links allow the locomotive to wing for side to side.

The weight of the locomotive rests on the Helical springs and Leaf spring, which compress when it passes over a bump. The links allow the trucks to move from side to side with fluctuations in the truck. The truck is not perfectly straight, and at high speeds, the small variations in the track would make for a rough ride if the trucks could not swing laterally. The system also keeps the amount of weight on each rail relatively equal, reducing wear on the tracks and wheels.

There are three pivots on which the load is distributed as 60%, 20%, 20% respectively on centre pivot, on two side bearers which are elliptical in shape. For distributing the load equally on the axles the equalizer beams are used.

While running the defects which generally occur are:-

1. Crack in equalizer due to stress concentration.2. Breaking of centre pivot due to inertia force.3. There might be failure of spring.4. Cylinder head section

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The working of cylinder head is to do maintenance work on the cylinder head. The maintenance and testing of cylinder of cylinder head is done by this section. The complete overhauling procedures includes the following steps:-

1. Disassembling of valves and their springs and checking the tapered face of the valve kept for the indentations.

2. Washing of head, it is done for about 4 hours.3. The separated part are send for zyglo-test.4. All the clearances are checked and the two main

tests(Hydraulic testing to check the cracks in the water jackets and Blow By to check the proper seat matching of the cylinder head and liner) are done.

5. Assembling of all parts is done.

4 TESTS CONDUCTING ON CYLINDER ON CYLINDER HEAD

HYDRAULIC TESTING

In this testing the head is testing for any type of water leakage from the water jackets made for cooling system . there may be some cracks on the edges or near the valves sheet. for this the one side of the water outlet is closed and the fluid at the pressure of 70psi and at the temperature of 900 C is inserted and if there is any crack then there will be some leakage and the appropriate action is taken.

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LUBE OIL TESTING

In lube oil cooler there are about 440 tubes from which water circulates due to high temperature . so there may be some cracks formed. For checking the cooler is cleaned and then fluid at a pressure of 10-54psi is injected in the tubes at 850 C for about 4 hours. This will detect any type of leakage. The same process is repeated for after cooler testing.

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For the testing of the valves they are cleaned and then send to zyglo lab for checking the cracks. They are also checked for clearances an descend for grinding. These clearances are as follows:-

Valve guide 2.25” Angle of vsi 44.5” Valves insert dia 3.063” Spring height 0.0045” – 0.0054”

at load of 118psiTorque values of headCylinder head nut 75lbs

THESE ARE THE IMPORTANT PROCESSES WHICH ARE HELD IN THIS SECTION.

POWER PACK SECTION

The work of the power pack is to do the fitting work of the head on the loco. They take out head from the engine and assembled it again on the loco. In the power pack section the assembly of piston and connecting rod is done. The thorough checking of piston is done in this section. The piston is send for zyglo test then it is checked for all the clearances. It is checked whether the piston is seizing or not.

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There are two types of piston used modified and unmodified. In modified piston and piston head is made up of steel, the piston skirt is made up of aluminum. Unmodified piston is totally made up of steel only. The weight of the assembly is of 90kg.

There are generally 5 rings used in the cylinder, first 3 are compression ring next 2 are oil rings. The first one is made up of steel and has square face. The second one is also of steel and has tapered face. The third one is of C.I. and is fuel efficient taper face. The fourth and fifth are also of C.I. and are called oil scrapper rings.

These parameters are checked for the following parts.

Compression rings (in inches)

Groove width 0.1900-0.1920” Clearance in grooves 0.005-0.009” Thickness 0.1835-0.1850” Gap 0.0300-0.2000”

Oil scrapper ring (In inches)

Groove width 0.3140-0.3150” Thickness 0.3105-0.3125” Gap 0.0300-0.139”

Piston pin (In inches)

Diameter 3.7490-3.7590” Pin to bushing clearance 0.051-0.139”

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SPEEDOMETER SECTION

In this section all the gauges of an engine are tested in every schedule. If they are not working properly they are changed. In the checking process the memory card is checked and replaced. The memory cards records the data of speed at every moment when the loco runs on the line. This information makes the maintenance process much easier.

The control panel of WDM2 has:-

1. Two vacuum gauges2. Two vacuum duplex3. Two main reservoir duplex4. Two air flow gauge5. HS-4-gauge6. Central air gauge7. Fuel and lube oil gauge

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F.I.P. SECTION

F.I.P. is one of the most important parts of the loco. It stands for fuel injection pump

Fine spray is needed for successful ignition of the fuel. So the fuel has to be pumped into the cylinder ay high pressure.

The fuel pump is operated by a cam driven of the engine. The fuel is pumped into the injector which injects the fuel in the form of very fine spray, required for combustion in the cylinder. For this purpose a multipoint fuel injection system is used. Nozzle is made up brass and has nine holes through which the fuel is sprayed uniformly.

So, the fuel injector is an important part of an engine. In the schedule the F.I.P. is overhauled. It is disassembled and then checked for any distortion at a high pressure has to be maintaining at the time of injection.

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Nozzle is tested at the pressure of:-

New nozzle 3900 psi to 4050 psi

Old nozzle 3700 psi to 3800 psi

Testing of nozzle by using a hydraulic press.

Spray pattern of the fuel should be uniform. There should be noise of chattering at testing. The nozzle holes are cleared by 0.3mm diameter wire. The pressure of injection can be changed by adding or removing the compensating washers (shim) which are available in different thickness. The nozzle is tested at following specific data:-

Nozzle tip dia 0.44-0.65mm R.P.M. 500 Stroke 300 Temp. 100-1200 C Pressure 40psi Viscosity 6.8-7.1 cst at 300 C

(Fuel oil)

After the testing high pressure tubes in N.D.T lab the F.I.P. is cleared.

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FUEL SECTION

This section deals with the fuel transaction. It delivers the report to the management & passes its requirement. The oil comes from IOC, BPC, and HPC. The total oil expenditure of 4700 crore rupees/year is a big amount so this is one of the most concentrating fields for the government. So a report is sent to the head office daily.

The oil comes to the shed by road or by train. When the oil comes to the shed many data are to be filled and sent to head office as the quantity of oil, capacity, date of loading unloading etc. are prepared in the presence of government inspector & the person from company.

Before unloading following thing are checked.

1. The oil is tested by lube oil lab.2. The temperature at time of unloading and by

multiplying by the temp. with the Correction factor, the exact volume is calculated.

3. The moisture in the oil is checked.

Following important factors are considered by the fuel section.

1. Fuel consumption rate of shed. (gross tone/kilometer, per unit tone/kilometer)

2. Economic factor.3. Maintaining safety standard.4. Oil testing.5. Temp. correction factor.6. Wastage allowed only 0.001%.

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For further records fuel trip cards are maintained by the driver in this lube oil change, fuel oil are filled by the driver & kept in record. These all records came in major schedule & send to major head office.

The oil used are:-

HSD High speed diesel as fuel oil

RR-813 Engine block lube oil

RR 407 Expressor oil

T77 grade oil Governor, traction generator, wick lube

Cadmium compound gear & pinion on axle, fast coupling

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PIT WHEEL LATHE SECTION

When the loco is on line there are many types of tracks in the way on which driver has to apply brakes. At the time of braking there are many possibilities of skidding due to sudden braking. When two metals slide upon each other the wear of both the metal occurs. So due this reason the wheel wears when this wear flatness exceed 50mm of length, then the wheel needs treatment. The wheel are machined in this section. So, for making the wheel perfectly round the wheel are send to this section. The lathe is installed in pit, hence is the name “Pit Wheel Lathe”.

TRACTION MOTOR AND GENERATOR SECTION

This giant engine is hooked up to an equally impressive generator. It is about 6 feet (1.8m) in diameter and weights about 17,700 pounds (8029kg). at peak power this generator makes enough electricity to power a neighborhood of about 1,000 houses.

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So, where does all the power go? It goes into six, massive electric motors located in the bogies.

The engine rotates the crank shaft at up to 1000rpm and this drivesthe various items need to power the locomotive. As the transmission is electric the engine is used as the power source for the electricity generator or alternator.

MAIN ALTERNATOR

The diesel engine drives the main alternator which provides the power to move the train. The alternator generator AC electricity which is used to provide for traction motors mounts of the axles of the bogies.

In older locomotives, the alternator was a DC machine, called a generator. It produce direct current which was used to provide power for DC traction motor. Many of these machines are still in regular use. the next development was the replacement of the generator by the alternator but still using DC traction motor. The AC output is rectified to give the DC required for the motors.

AUXILIARY ALTERNATORS

Locomotives used are equipped with an auxiliary alternators. This provide AC power for lighting, air conditioning, etc. on the train. The output is transmitted on the train through an auxiliary power line. The output from the main alternator is AC but it can be used in locomotive with either DC or AC traction motors. DC motors where the traditional type use for many years but, AC motors have become standard new locomotives. They are cheaper to build and cost less to maintain and to convert the AC output from the main alternator to DC, rectifiers are required. If the motors are DC, the

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output from the rectifiers is used directly. If the motors are AC the DC output from the rectifier is converted to 3-phase AC for the traction motors.

TRACTION MOTORS.

Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the axles to give the final drive. These motors where the traditionally DC but the development of modern power and control electronics has led to the introduction of 3-phase AC motors. There are between four & six motors on most diesel electric locomotives. A modern AC motors with air blowing can provide up to 1000hp

INDIRECTLY ASSISTING SECTIONS

Those sections which indirectly assist in the maintenance work are called indirectly assisting sections. The labs generally come under this sections. The various indirectly assisting section are as follows:-

1. Speedometer lab2. Metallurgical lab 3. Machine shop4. Millwright sections5. C.T.A. cell6. Control room

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The brief introductions of these section are given below.

SPEEDOMETER LAB

When the loco comes for a schedule, the lube oil of the loco checked thoroughly. When the metals slides over each other

Sometimes they cause wear, but there is continuous flow of lube oil between them which takes those particles with them. This increases the quality of different metals in them. So, in this lab the different percentage of elements are taken out by electronics method.

In this test, a very thin film is created between two graphite electrodes having high potential difference between them. This causes a spark between them which carries a high temperature (25000 C). this process is done in UV-Rays. So the valence electrons of different element in outer shell get excited and jump to the excited level. They remain there for 10-2 sec. when they come down to normal state they release energy in the form of light rays. Different elements release different intensity waves which are focused on a different grating, which splits the light into a spectrum. These spectrum lights are focused on the potential tubes based on photo electric effect. This generates electric signals that are read & compared by the computer to the standard data. The data is as follows:-

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Elements Min. Limit (in ppm)

Max. limit (in ppm)

Cu 10 20Pb 5 10Sn 5 10Fe 20 50Cr 5 10Na 30 50Al 5 10Si 15 20B 10 20

So according to these limits we can easily detect which metal is wearing more, and according to that which part has to be checked and changed.

MACHINE SHOP

In this section machining of different parts is done. The machine shop has different lathe, grinding machine, power hacksaw, drill machine & shaper machine. But the machining of very few components like expresser shaft, generator armature is done and most of the parts are replaced because there is no comprise for the efficiency.

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METALLURGICAL LAB

In this section the properties of the lube oil & fuel oil are tested and if they are up to the mark then they are only used.

The standard properties of the fluids are as follows:-

Fuel Oil Properties

Acidity nil

Pour point 3oC(winter)15oC(summer)

Distillation record(370oC) 95% min.

Flash point 35oC min.

Kinematic viscosity (40oC) 2 – 5 cst.

Density (15oC) 820-860 kg/m3

Sulphur max% by weight 0.25

Water max% by volume 0.05

Carbon residue % wise by weight 0.30

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Lube oil properties

Appearance clean & bright

Kinematic viscosity (100oC) 15.5 – 16.3 cst

Viscosity index - 110min.

Pour point - 21max

Flash point - 200oC

Sulphur - 1.39-1.63%

Different tests are conducted on the oil and their properties are tested out. If the readings are different then the action is taken by the administration.

MILLWRIGHT SECTION

In this section the maintenance work of helping machine is done.

The maintenance of supporting machines are done as:-1. Cranes. Hydraulic jacks.2. Air compressors.3. Water compressors.4. Air pipe lines.5. Water pipe line etc.

C.T.A CELL

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The information for any movement is necessary to be given to the head office. So there should be a body which can form a like between administration and the shed. This is done by C.T.A cell.

The few main works are as:-

1. Interaction between H.O and shed.2. To keep check of the technical view on the working in

the shed.3. To check the work quality according to the standards.4. To solves the problem s of the shed’s different

departments.5. To contact the concerned private agencies if there is

some problems in their services.6. To maintain the standard criteria of I.S.O as they need

the six monthly contracts.

So, in this way C.T.A cell plays an important role of interaction between shed and administration.

CONTROL ROOM

There are several locos in the shed, so it is important to have a proper schedule to maintain them and to maintain proper outage of the shed. This work is done by the control room. It is the link between the shed and each every loco. It forms an interface between the on line and the shed. Control room maintains the record of each and every failure. They decide when a loco has to come back in shed and when it has to besent on the line. For this they have maintained a system which automatically let them know which loco is running where. If a loco fails on line then control

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room has to deal with it. So this is the department which keeps the track of a loco at every moment.

EXPRESSOR IN DIESEL LOCOMOTIVES

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IN Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air brakes. As such provision has been made on every diesel loco for both vacuum and compressed air for operation of the system as a combination brake system for simultaneous application on locomotive and train.

In ALCO locos the exhauster and the compressor are combined into one unit and it is known as EXPRESSOR. It creates 22" of vacuum in the train pipe and 140 PSI air pressure in the reservoir for operating the brake system and use in the control system etc.

The expressor is located at the free end of the engine block and driven through the extension shaft attached to the engine crank shaft. The two are coupled together by splined flexible coupling (Kopper's coupling)/Cardan shaft. Naturally the expressor crank shaft has eight speeds like the engine crank shaft and runs between 400 RPM to 1000 RPM range

CONSTRUCTION AND DESCRIPTION

The expressor consists of the following components mainly; 1. Crank Case 2. Crank shaft 3. Four/Three exhauster cylinders with cylinder heads 4. One/Two low pressure compressor cylinder with cylinder head. 5. One high pressure cylinder with cylinder head.

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6. Six pistons with connecting rods (including one/two LP, one HP and four/three exhausters.) 7. Lube oil pump.

Each of two crank journals supports three connecting rods. The crankshaft is supported at the both ends by double row ball bearings. Outside the ball bearings are located oil seals to prevent the leakage of oil from inside the crank case and air from out side into it. Crankcase breathers are provided to vent the compressor crankcase.

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MODELS OF EXPRESSORS USED IN DIESEL LOCOS

There are two models commonly used in Diesel Locos. They are 1. 6CD-4UC

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2. 6CD-3UC

In 6CD-4UC Expressor, there are six cylinders out of which the one having smaller diameter acts as HP and one LP and four exhausters while in 6CD-3UC, there are one HP, two LP and three exhausters.

In both models, the LP cylinder head and each exhaust cylinder head contains two inlet and two discharge valves and the HP cylinder head contains one/two inlet and discharge valves. The valves are such that they have liberal air flow passages to avoid flow restrictions and to prevent excessive heating and choking of valve ports with carbon deposits due thermal decomposition of lube oil. The retainer stud in both the assemblies must project upward to avoid hitting the piston. The inlet valves of both LP and HP cylinders are equipped with unloaders which help to unload the compressor when the desired pressure in the main air reservoir is reached. Similarly, the compressor cylinders are loaded whenever there is a drop in air pressure.

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WORKING

Compressor

The compressor is a two stage compressor with one LP cylinder and one HP cylinder. During the first stage of compression it is done in the LP cylinder. As the piston of LP cylinder starts moving downward, the combined action of discharge valve return springs and the pressure differential existing between the discharge manifold and the LP cylinder closes the discharge valves. At same time inlet valves open due to pressure differential existing between inside and outside the LP cylinder. The atmospheric air is then sucked into the cylinder through an intake strainer (wire mesh filter) mounted horizontally. During the upward stroke of the piston, the combined action of inlet valve springs and pressure differential existing between inside and outside the LP cylinder closes the inlet valves. The air present in the cylinder above the piston is then compressed. Towards the end of the upward stroke, the compressed air opens the discharge valves due to the pressure differential existing between the discharge manifold and the cylinder. After compression in the LP cylinder air is delivered into the discharge manifold at a pressure of 30 / 35 PSI. Thus the compressed air reaches the intercooler which is of radiator type cools the low pressure compressed air before further compression in the HP cylinder. After the first stage of compression and after-cooling the air is again compressed in a cylinder of smaller diameter to increase the pressure to 135-140

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PSI in the same way. This is the second stage of

compression in the HP cylinder. Air again needs cooling before it is finally sent to the air reservoir and this is done while the air passes through a set of zigzag tubes below the loco superstructure. Thus finally the output of HP cylinder is discharged into the main air reservoir.

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Loading and Unloading of Compressor

To avoid the compressor running hot due to overloading and also to avoid the wastage of engine horse power, arrangements are provided to unload the compressor when a particular pressure is reached. In other words the compressor cylinders are not required to compress air any further when the main reservoir pressure reaches 10kg/sq.cm. So the compressor stops loading the main reservoir. Due to no further compression being done, reservoir pressure naturally falls due to normal consumption and leakages. When the MR pressure come down to 8kg/sq.cm. The compressor resumes loading of the MR again. Generally, the time taken for loading and unloading should be in the ratio of 1:3.

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Basically in these compressors unloading is effected by the unloader plunger prongs pressing down the inlet valves of both LP and HP cylinders to keep them in open position as soon as 10kg pressure is reached in the M.R. It continues to be so till the pressure comes down to 8kg/sq.cm. Thus the compressor remains unloaded or relieved of load in the range between 10 to 8kg/sq.cm. MR pressure. In this case, the LP cylinder air drawn in through the intake filter is thrown out in the same direction. In case of the HP cylinder air is pushed back to the inter cooler and LP discharge manifold. This is achieved through the function of the unloader plunger in conjunction with the air governor. The added advantage of unloading process is that the air which goes out without getting compressed during the unloading process cools the system.

EXHAUSTER

Air from the vacuum brake pipe is drawn into the inlet side of the exhauster head. The inlet faces of the exhauster heads are connected by two inlet manifolds. Two exhauster cylinders are attached to each manifold. There are two inlet valves and two discharge valves in each cylinder head. During the downward stroke of the piston, air is drawn through the inlet valves into the exhauster cylinders. The pressure differential existing between inside and outside of the exhauster cylinders closes the discharge valves. As the piston moves upward, the air is compressed slightly above the atmospheric pressure and passes through the discharge valve into the discharge manifolds. During the upward stroke, the combined action of the inlet valve return springs and pressure differential existing between the vacuum reservoir and the exhauster cylinders will close the inlet valves. At the same time, the compressed air will open the discharge valve near the end of upward stroke of the piston.

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This process of suction of air from the train pipe continues to create required amount of vacuum which is 23 inch of Hg and discharge the same air to atmosphere. The VA-1 Control Valve helps in maintaining the vacuum to requisite level despite continued working of the exhauster.

LUBRICATION SYSTEM

The lube oil system of the expressor is a force feed pressure lubrication system, independent of the lube oil system of the engine. Lubricating oil of SAE 30 or SAE 40 grades is filled in the sump of 21lts. capacity. The lubricating oil is filled through the filler assembly into the crankcase. An oil pump which is of chain-driven gear type circulates the oil under pressure through the system as shown in fig. The oil pump is driven by a sprocket mounted on one of the two pump gears which takes drive from the crank shaft of the expressor through a sprocket and chain. A strainer screen which is held in place by screen retainer filters the oil before oil is drawn up into the inlet port of the gear pump. The oil after filtration is carried around the gears to where the gears mesh. The meshing action forces the oil upward to the discharge port. A port takes the oil up to the groove in distributing ring of the oil pump body.

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From the distributing ring, oil flows to each crank-pin through drilled passages in the crankshaft. These holes connect to distributing holes drilled axially through each crank-pin of the crankshaft. Each crank-pin is cross drilled to supply oil to three connecting rods. This also provides lubrication for the six connecting rod insert bearings. The top half of each insert bearing of the connecting rod is grooved and ported to deliver oil to the wrist pin bushing and the cylinder liner The oil pressure in the system is limited to 25-60 psi (40 psi at idle, 60 psi at full speed) by relief valve located in the oil pump body. The relief valve is spring weighed and maintains the lubricating oil pressure in the compressor at designed setting. When the oil line pressure exceeds, the relief valve is unseated allowing oil to pass out to the sump. An oil pressure indicator gauge indicates the oil pressure of the system. The gauge is mounted on the side cover of the crankcase. Pressure reaches the gauge by means of a tube leading from the lower pipe tap on the pump body to the gauge port in side cover. The magnetic drain plugs one on either side of the crankcase is meant for draining oil from the crankcase and to collect iron particles in the oil sump.

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COOLING SYSTEM

Cooling in expressors is done at two stages. At the first stage, compressed air from LP cylinder is cooled in the intercooler before going into the HP cylinder thereby increasing compressor’s volumetric and overall efficiency. At the second stage, compressed air from the HP cylinder is cooled by passing it through a set of zigzag tubes below the loco superstructure before going to the MR tank. Intercooler is of adequate thermal capacity with large heat dissipation area consisting of finned tubing mounted between cast iron headers which act as cooling ribs. This is an air to air cooler where compressed air enters the top header and passes down in one half and comes up through the remaining half of the tubes. Cool atmospheric air is blown on the outside fins by a fan fitted on the expressor crank shaft. The fan also cools cylinder and cylinder heads. The direction of the air flow is such that hot air from the diesel engine does not pass over the expressor. A safety valve set

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at 60 psi is fitted to the intercooler to afford necessary protection to the intercooler and LP cylinder equipment against excessive pressureAIR INTAKE STRAINER

The inlet air for LP cylinder of expressor is filtered by one horizontally mounted viscous type air intake filter. The main parts of strainer filter are

1. Strainer element made of metal wire mesh.2. Latch bail to hold the strainer element in position.3. Strainer gasket.4. Fittings to hold the complete strainer assembly on to the

inlet side of the LP cylinder.

INLET AND DISCHARGE VALVES

All the inlet and discharge valves are of double disk type. The valves springs of inlet and discharge valve assemblies are completely interchangeable. All inlet valve assembly has same valve seat; all discharge assembly have same valve seat.The inlet valves of LP and HP cylinders are equipped with unloaders which are controlled by governor.

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PISTON

The LP and exhauster pistons are made of Aluminum alloy whereas HP piston is made of cast iron. Four piston rings are fitted on each piston. The upper two rings are compression rings and other two are oil rings.

CONNECTING ROD

Expressor has six identical connecting rods of forged steel. These are mounted on each crankpin of the crankshaft. Each connecting rod has replaceable insert bearings on the big end. The smaller end of LP and exhauster connecting rods have bush bearings where as that of HP has roller bearings.

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CRANKSHAFT AND CRANKCASE

The crankshaft is coupled together by splined flexible coupling (Kopper's coupling)/Cardan shaft directly to the diesel engine. The crankshaft dynamically balanced to ensure smoothness of operation, is supported on two main bearings, one at each end of the crankshaft. The bearings are double row ball ty

CRANKCASE It is housing for crankshaft, connecting rods and lubrication system. It is under partial vacuum which is achieved by connecting the crankcase to the inlet manifold of the exhauster by means of a pipe through the vacuum maintaining valve to prevent oil throw through the exhaust.

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VACUUM MAINTAINING VALVE

When there is a pressure buildup in the crankcase, the piston in the vacuum maintaining valve moves up assisted by spring pressure to open the port connecting the crankcase to inlet manifold of the exhauster, thereby evacuating the crankcase. When the vacuum in the crankcase reaches the predetermined value as set, the same is maintained at that level by the piston moving down and cutting off manifold connection.

GOVERNOR

The function of the air governor is to transmit main air reservoir pressure to the top of unloader plunger as soon as the MR pressure reaches 10 kg/sq.cm and process of unloading starts. With the fall of pressure to 8kg/sq cm the same supply is discontinued and existing pressure in the unloader valve is vented out.The NS-16 air governor consists of governor body in two pieces of bronze castings and a pipe bracket with a number of air passages. It also incorporates (1) wire mesh filter (2) cut out cock (3) cut out adjusting stem (4) cut out valve spring (5) cut out valve spring adjusting nut (6) cut in tail valve (7) cut in valve (8) cut in

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valve adjusting stem (9) cut in valve spring (10) cut in valve adjusting nut.

When MR pressure gets access into the air governor through pipe A, it passes through the filter (1) to passage B and then bifurcates in the pipe bracket. A part of this air passes through the passage C at the bottom of the cut out valve. The other portion of the air passes through passage D and work on the cut in tail valve.

Once the MR pressure reaches 10 kg/sq. cm, the pressure acting at the bottom of the cut out valve overcomes the cut out valve spring tension and lifts the valve to get access to passage E. The air pressure acting on cut in tail valve lifts the cut in valve thereby opening the passage from E to F which leads to the top of the unloader plunger. At the same time the exhaust passage G of the casting is blocked by the upper lips of cut in valve.

Once the MR pressure goes below 10kg/sq.cm.But remains above 8kg/sq.cm the cut out valve spring forces the cut out valve to be seated and the passage from C to E is blocked. But the cut in valve is still kept up with the help of pressure between 10kg/sq.cm to 8kg/sq.cm and the amount of air passing through the cut in tail valve keeps on supplying air to the unloader valve top.

As soon as the MR pressure drops to 8kg/sq.cm, or below the cut in valve spring closes the valve and thereby block the passage to F and no further air is supplied to the top of unloader. Further, whatever air is there in the pipe line is exhausted as soon as the cut in tail valve upper lips move down opening the connecting passage G to exhaust port.

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INSTALLATION

For the installation of a new expressor or the overhauled expressor requires careful consideration since proper alignment with the diesel engine is involved, in the alignment is not properly done, the negligence of accuracy will cause unsatisfactory results and a sort life for the unit. Two condition may arise under which expressor is replaced or reinstalled. In either case, perfect alignment be ensured.

First, if the diesel engine has been removed, which usually means that the expressor has also been removed. If the expressor only has been removed for replacement. In the first case it is very important that alignment of expressor should not be started until the diesel engine, generator, and auxiliaries, including fuel tanks, have been properly installed and secured in place and fuel, water and necessary lubricating ail have been supplied.

The reason for this important procedure is that there is an arc in the locomotive frame which will level off under the load of machinery. Therefore, the expressor should not be permanently place in position, and aligned with the diesel engine until the locomotive body frame has leveled off and is approximately straight.

Under either condition, as mentioned above, the alignment should checked wit an indicator in order to obtain correct level. If possible, dial indicator should be used to check coupling alignment in all directions to ensure that there is no misalignment. Under any condition, when the coupling between the diesel engine compressors exhausted is parted, it is important to check that proper alignment is obtained before the coupling is again

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tightened. Further, coupling must be inspected periodically for tightness and mechanical defects and wear

MAINTAINENCE SCHEDULE

TRIP INSPECTION

Check oil level and top up, as required, with the diesel engine stopped.

Drain condensate from intercooler.

The recommended lubricants for the expressor SERVO PRESS 150 of IOC make.

MONTHLY INSPECTION (30 DAYS)

Clean the air intake filter of the compressor with engine stopped. Clean the strainer of the expressor governor and the oil strainer of the expressor.

Check and record crankcase vacuum with diesel engine running.

Check the oil level.

Check whether there is any leakage of oil at the shaft seal.

QUATERLY INSPECTION (3 MONTHS)

Clean and inspect valve assembles, with the engine stopped. Renew gaskets between the wall assembly and the cylinder head.

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RECONDITION ON LOADERS.

Drain, clean and refill cranks case, check the split pin of the drive chain to ensure that it is well secured and tight, before filling. Clean oil strainer. Check alignment of drive. Inspect the piping for tightness for crank case check valve. Insure that the orifice is free from obstructions. Measure cranks case lube oil pressure and record with engine running.

Check the temperature of cylinder heads. If it beyond the normal, find out the fault, with the engine running and rectify it.

HALF YEARLY INSPECTION (WITH ENGINE RUNNING)

Clean and oil expressor governor. Ensure that the exhaust opening is free from dirt gum. Perform orifice test. Use the 8.70 mm diameter orifice for the compressor and 12.7mm diameter orifice for the exhauster portion. Maintain the capacity within the values shown in the graphs.

YEARLY INSPECTION (WITH ENGINE STOPPED 24 MONTHS)

Examine the oil pump, gears and the oil pump relief value of the expressor.

Examine intercooler safety valves and check their performance.

Decarbonizes the piston and the renew rings, if necessary.

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TRIENNIAL INSPECTION

Carry out break- in test on the locomotive and then check the performance by orifice test if a test stand is not available Drain and refill lubricating oil during the first fort nightly scheduled to remove all wear in particles.

GENERAL

Check the condition of all other parts to avoid any OUT OF COURSE attention when expressor is removed from the locomotive and dismantled for renewal of the face type carbon steels. Dismantle the expressor if its leaks oil trough face type carbon seal due to its deterioration.

REPAIRS

RECONDITIONING CYLINDER AND PISTON WITOUT REMOVING EXPRESSOR FROM LOCOMOTIVE. It certainly proves the to be advantageous to do the repair work with out removing the expressor from the locomotive. For this the procedure adopted to secure maximum benefits greatly enhances the quality of repair work done on the unit. The actual delivery of air found out by conducting the office test. The damaged condition of the valves piston rings and cylinder indicate the deficiency in the actual delivery of air as conducted by the orifice test. The damaged parts should be carefully examined and replaced. Subsequent cleaning is necessary to decarbonize the valves and the cylinders heads and check again. Even after observing the above procedures if the orifice test not satisfactory, the cylinders and

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pistons should be removed for carefully analysis. The position of cylinder in the cranks case should be marked per identification. The connecting rod bearing and wrist pin should be I good condition and the wrist pin in their respective connecting rods, when checking the maximum & minimum clearance.

DISMENTALING EXPRESSOR FOR OVERHAUL

REMOVAL FROM LOCOMOTIVE

On doing major overhaul the seems used for alignment at the basement should be left as it is their respective position so that it facilitates the reinstallation of the same expressor on the same locomotive from which it has been removed. This saves times and effort spends for the correct alignment of the unit with the basement in the locomotive.

REMOVAL OF COUPLING

The expressor exhauster bearing should be well protected any damages, while removing the coupling from or refitting to crank shaft. The coupling hub should be heated quickly while using a gears puller to facilitating the removal. Couplings are shrunk fit on the sharp. The clamping screws on the coupling and remove for facilitating the removal of fan from the coupling half. Crank shaft locked nut is removed from the sharp and a cooler is used to removed the coupling half. Now the other accessories such as the intercooler, intake strainers, piping to the governor, oil gauge, and exhauster many folds and side covers are removed.

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The cup nut, spring shims and the piston of oil pressure indicator are also removed.

OIL PUMP DISMENTALING

For dismantling the oil pump assembly.

1. Removed the tube connecting the oil pressure indicator to the oil pump body.

2. Loosen the lock nut and set is screws which holds oil strainer body in place, then removed the oil or strainer body and then remove the sprocket screw and stay pin, from the oil pump body. Remove the strainer.

3. Take out the master link to remove the derive chain.

4. The lock wire and torque screws and removed to remove the oil pump body.

5. The lock wire and the two cap screws are removed to remove the oil pump bearing cap at crank shaft end.

6. Remove the crank shaft sprocket and after removing the lock ire to shoulder screw which holds it in place.

7. The dry key from the crank shaft is also removed.

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REMOVAL OF OTHER PARTS

1. Remove the cylinder heads, cylinder connecting rods, piston, and crankshaft.

2. Place the crank case in position so that the axis of the crank shaft is vertical and men bearing facing upwards, when dismantling the cranks assembly. Wild dismantling cranks all possible care is to be taken avoid damaged to the ball bearings.

3. The end cover which is secure to the crank case by means of cap screw is removed. Three ½ inches UNC screws should be inserted to the tapped holes in the end cover and gradually tighten all the screws simultaneously by equal amounts. The end cover is thus raised gradually, until it is possible to apply a gears pulls to the edge of the housing. Then use a puller and removed the end cover.

4. In applying the puller care should be taken so the crank shaft center is not damaged. For this a tick metal disc can use between the gears puller screws and the crank shaft.

5. A lifting device is necessary for removing the crank shaft. This lifting device consists of a threaded portion to which is welded a ‘V’ shaped loop of sufficient size to permit the insertion of the hook of the lifting equipment. Apply the nut to the end of the crank shaft

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knock its upper end back and forth at right angles to its axis. The shaft is to be removed without causing damaged to the bearings for this it should be checked the lifting force is in line with the crank shaft to prevent wedging acting between the bearing and crank shaft.GENERAL REPAIRS

Inspection has to be carried out and for this all parts should be thoroughly, the drilled all passages, oil ling should be free from any obstruction and should be checked for any damages. If there are any damages in crank shaft it should be replaced.

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TABLE OF CLEARANCES

Check thoroughly the respective matching parts for correct clearance and do suitable repairs.

S. No

Details of clearance

Minimum Maximum

1. L.P & Vacuum cylinder Piston to cylinder

Piston ring side

Piston ring gap

0.210

0.051

0.584

0.255

0.101

0.914

2. H.P cylinder

Piston to cylinder

Piston ring side

Piston ring gap

0.175

0.04

0.431

0.225

0.100

0.762

3. Main 0.381 -------

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bearing

4. Conn.rod to crack pin

0.0381 0.0965

5. Conn. Rod big end side

0.508 0.812

6. Gudgeon pin to conn.rod

0.020 0.0381

7. Oil pump bearing collar to crankshaft.

0.114 ---------

8. Oil pump bearing end clearance

0.381 ---------

9. Valve lift

1.83 2.06

10. Valve thickness

1.17 --------

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CYLINDERS AND POSITIONS:

Cylinders and position should be carefully inspected any damages. If there is any damages like irregularities on the inner walls of the cylinders, honing should be done.

The perpendicularity of the cylinders within their flange face should not be more than 0.0508mm. Check the perpendicularity by mounting the cylinders in a lathe or boring mill and truing both ends of the bore with a dial indicator.

Care should be taken while machine the flanges, not to shorten the length of the cylinders beyond the minimum limit, i.e. when reassembled and with the piston in top dead centre position, the top of the piston must be either flush with or below the top face of the cylinder

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Clearance should be checked between the piston and the cylinder with the rings removed from the piston. Now reinstall the piston into respective cylinder from which it was removed if this clearance is found to be within the limits specific under repair specification.

Replace a new standard size piston giving the correct clearance limits provided the old piston and cylinder is not within the limits specified in the tabulation under repairs specifications. Try a new standard size cylinder if the clearance cannot be brought within the given limits by changing a new standard size piston. If necessary, rebore and hone the cylinder to a suitable 3

standard oversize diameter while maintaining the finish as specified. If the cylinder is bored oversize use the respective oversize piston.

PISTON RINGS:

Reassemble the piston rings with the position of the exact type and size as shown in the when the cylinders and the piston meet the

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dimensional requirements as mentioned in the above table. After assembling the piston rings, see the position rings get sited in the ring grooves with proper clearance which if neglected may cause exes of oil leakage. Check the piston ring gap to be correct, if is not maintained correctly, it will cause overheating, piston seizure or cylinder scoring.

CRANKCASE

Check the crankcase for crack, creep and breakage at any of the side. If there are such defects, replace the crankcase. Rebush the main bearing if the bore is eccentric or worn more than 0.050mm, using a spare bushing, machine the crankcase bore diameter of

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196.776-0.0127 / +0.00 for using this bushing. Bore the bushing to a diameter of 189.995-0.00/+0.04 after it is pressed in place.

Replace the end cover if it is cracked or broken off or otherwise damaged beyond repair. Rebush the end cover using a spare busing if the main bearing bore is eccentric or worn more than 0.051 mm.

Bore the bushing to a diameter of 196. 773-0.00/+0.00. In using this bushing bore the bushing to a diameter of 189.995-0.00/+0.04 after it is pressed in place.

Replace the end cover if it is cracked or broken off or otherwise damaged beyond repair. Rebush the end cover using a spare busing if the main bearing bore is eccentric or worn more than 0.051 mm. bore the end cover to a diameter of 196.773-0.0127/+0.00, for using this busing; bore the bushing to a diameter of 189.995-0.00/+0.04 after it is pressed in place.

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CRANKSHAFT:-

Arrangement for checking alignment of crankshaft . When the condition of the crankshaft is poor, being broken or bend or ball bearing worn out to less than 90.0049mm, tapered or threads damaged so that it cannot be used again, then replace it with a new one.

CRANKSHAFT ALIGNMENT CHECK:

Stage: I

Make sure that the centering holes are absolutely dust proof and free from other particles and it without any damage.

Stage: II

Fix the crankshaft to the centering post.

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Stage: III

Check the point P, R&T. By using a dial indicator finds the maximum points at diameter P from reference surface while roating the crankshaft through 360 degrees. The same procedure may be followed for R and T. at diameter P, R, & T the distance can be checked from the checking surface to the maximum points. The indicator gauge reading will show 0.051 mm while rotating the crankshaft through 360 degrees.

CHECKING ARRANGEMENT OF CRANKSHAFT ALIGNMENT

If the crankpin has worn out to 91.986 mm grind it or if worn of round more then. 0.0254 mm to a definite under size step of 0.254mm, 0.762mm, 1.016 mm or if reliable facilities are available; consider chrome plating and subsequent regrinding to the respective standards diameters. The radius of crankpin should be maintained 3.175 mm with grinding under size diameters.

The crankpin finish should be 0.4 micron or better. Use felt or glass wool to remove roughness and polish tightly after grinding. The dimension should be maintained as given below. If there is any sore marks visible on the oil seals seats of the expressor crankshaft it can be refinished. The finishing should not exceed the roughness of 0.4 micron. The standard compressor oil seal can be used if the finished diameter is not less than 68.62 mm.

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Marks the crankshaft in a visible location with its respective undersize letter W, Y, G and B paint with the color denoted as follows.

W White 0.254 Undersized

Y Yellow 0.508 Undersized

G Green 0.762 Undersized

B black 1.016 Undersized

The crankpin throw must be held to 71.437 ± 0.051 dia.

INTRODUCTION

The expressor which has gone through a thorough inspection and reconditioning should be put to a bear in a run for a

considerable period.

It should be remembered that the bear in run must be done at a reasonable speed whenever it has undergone reconditioning and general overhauling; particularly piston, rings and cylinders. Allow sufficient time for the self adjustment of the new parts and that are replaced. There will be a non uniform and rapid increase in temperature but after some time it will regain normal temperature. Since the parts have been replaced, there is a chance for

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temperature to vary. Never allow the expressor to ruin a high speed because if there is any misalignments, and it may cause severe damage to the unit.

Every operation should be followed up with much care so that the benefits achieved from precise re machining and refinishing should not be lost in the wear in period.

TESTING RIG

Construct a test stand at the place where the major over hall of expressor is to be carried as shown in the FIG. If the new test stand is not provided, we can conduct wear in test on the locomotive itself. Use a variable e speed motor of about 120HP or a constant speed motor with a multiple speed gear box to drive the expressor. Use belt drive provided no thrust is allowed on main bearing of expressor. Maintain the speed range for testing between 4000-1100 rpm and the initial speed should not be less than 400 rpm, to provide sufficient lubrication to all parts during the wear in.

TEST PROCEDURE

Lubricating oil such as SERVO PRESS 150 can be used during the wear- in period. Provide auxiliary cooling fan of capacity around 3600 cfm.

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METHOD OF OPERATION

SI. No

OPERATION PERIODS In hrs

Speed rpm

1 Operate against atmospheric pressure (Globe valve open, No orifice in the orifice holder

2 hrs(min)

400

to

500

2 Fit. 8.7 orifice on orifice holder, gradually close globe valve to rise pressure to 100 psig

2 hrs(min)

400

to

500

3 Close globe valve to raise pressure further to 140

2 hrs(min)

400

to

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psi and maintain 20” vacuum in the vacuum receiver.

500

4 Increase speed to max, service speed and adjust pressure to 140psi and vacuum to 23”Hg

2 hrs(min)

1000

5 Increase speed to max. service speed and adjust pressure to 140 psi and vacuum to 23

2 hrs(min)

1000

Stop the expressor for cooling and make it to run at the minimum speed and pressure. If there exist a high temperature and if it persists examine and check whether the cooling air is sufficient, proper lubrication and correct alignment and clearance. Dismantle the cylinder heads and check the valve assemblies for broken springs, damage or leakage involves or any other defects and rectify them.

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Conduct frequent test if any parts such as the pistons, rings, bearings, etc. have been replaced.

TESTING THE PERFORMANCE

Run the expressor again at a maximum speed and pressure and approximately 560mm of HG vacuum for a about 30 minutes to regain normal operating condition, at a speed of 400 – 500 rpm with the orifices 8.77mm, in the orifice holder on the pressure side on 12.7mm in the orifice holder on exhauster. Close the shut of valve on the air receiver. Note down the reading in the pressure gauge and vacuum gauge. Compare whether they consider according to graph for gives speed in the stabilize condition of the pressure.

STORAGE

The following procedure should be followed in case of storing the

expressor for more than three months.

1. The crankcase oil should be drained to the minimum level of the oil level of the indicator class.

2. Add about 500CC of antirust SERVO LINE 68 grade oil to each cylinder by removing the cps of the inlet and discharge valves.

3. Replace them run the compressor for about one minute at idol speed (400rpm) with air discharge lying and exhauster line open to atmosphere.

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4. Drop course grade silica gel approximately 2gm packed in a small packet in to the cylinder heads after removing the caps of the heads.

5. Crankcase oil should be drained and the expressor should not be run there after.

RESTARTING THE EXPRESSOR AFTER LONG

PERIOD

1. Remove the silica gel packed from the cylinder heads.2. Fill 30 litter SERVO PRESS 150 oil into the crankcase

expressor.3. Check for any abnormal noise in the engine at 400rpm

for about 50 minutes.

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FAILURES

1. Oil throwing and short of lubrication oil is the major problem in expressor which is caused due to the damage of piston or cylinder liner so there will be no vaccum in the cylinder leading to the throwing of lubrication oil out of the expressor. If the vacuum in the sump remain zero of then the whole lubrication oil will be thrown out within 3 or 4 hours. Damage of gaskets is also a problem of oil throwing.

2. Ineffective needle valve or indicator attached to the expressor has no lift to show the existence of vaccum in the sump. If a needle valve or non return valve is not working or choked, it means that the lubrication oil is not working properly.

3. Breaking the valves of expressor leads to the seizing of the expressor and also piston wears out.

4. Blockage of the pressure valves (high pressure and low pressure) of the governor of expressor with leads to the bursting of expressor within half an hour.

5. Failure due to the deposition of carbonized particles on the inter-cooler.

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SUGGESTIONS & CONCLUSION

A new expressor or overhauled expressor requires careful consideration of proper alignment with diesel engine. Improper alignment & negligence of accuracy will cause short life of expressor. It is very important that the alignment should not be started till the diesel, generator and auxiliaries have been properly installed in a secure place, water and lubrication oil have been supplied.

Expressor should not be permanently placed. All the alignment should be checked with an indicator. Coupling must be inspected periodically for tightness and defects. A proper cleaning is necessary to decarbonize the valves and cylinder head. The drilled oil passages, oil line should be free from any obstruction and should be checked for any damage.

Cylinders and piston should be carefully inspected. If there is any damage, honing should be done. Pistons ring should be reassembled with exact type and size. If there are any defects in crank case such as cracks, creep, breakage, it should be replaced.

All the above measures should be considered carefully for the proper working and long life of the expressor.

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