WORKSHOP DEPARTMENT

1.DISMANTLING SECTION

2.ENGINE OVERHAULING & ASSEMBLY SECTION

3.UNIT

4.FUEL INJECTION SECTION (FIS)

5.RETRIVAL

6.ELECTRICAL SECTION

7.SUSPENSION SECTIONAND VEHICLE OVERHAULING SECTION

BODY - BUILDING DEPARTMENT

1.WELDING SECTION

2.CARPENTRY & SHEET METAL SECTION

3.PAINTING SECTION

WORKSHOP DEPARTMENT

1.DISMANTLING SECTION

This section deals with the dismantling of the

various parts of the vehicle. The vehicle accessories

are separated to provide for keen scrutiny of the

defective parts.

Generally the overhauling is required in the

following events:

1. Power loss due to poor engine compression

2. Excessive consumption of lubricating oil.

3. Mechanical failures such as excessive noise due to

defective ignition or

injection.

The hood of the engine compartment is first

removed. All coolants hoses are disconnected, the

radiator mounting bolts are removed and the radiator

is lifted from the engine compartment. All wires,

tubing and controls connecting the engine to the

automobile are removed and tagged. The alternator and

fans are removed to avoid damage during removal of

engine. After that the driver shaft and exhaust pipes

are disconnected. The mounting bolts are at last

removed and the hoist is operated to lift the engine.

The dismantling procedure is then followed by:

Removal of:

1. Cylinder head.

2. Valves and valve mechanism.

3. Piston-connecting rod assembly.

4. Cylinder.

5. Crankshaft and main bearings.

2. ENGINE OVERHAULING AND ASSEMBLY SECTION

This department deals with the reconditioning and

testing of engines and engine parts. The

reconditioning process consists of various steps such

as de-assembly, maintenance and assembly of the

engine.

Duringthe de-assembly of the engine each part is

removed from the engine with great care. The main

parts while considering an engine are cylinder block,

cylinder head, crank case, And each have its own

sections for its maintenance. During the maintenance

of each engine, the damaged parts are found out and

it is replaced. And the non-damaged parts are cleaned

and reused. All parts are well lubricated and is

assembled. The testing of the engine is done at the

testing area. During the process the engine is tested

for analyzing its performance.

Cylinder in the block is the place where power is

generated. Hence after some use, they get worn out.

The cylinder block form the dismantled engine is

cleaned thoroughly, then boring and honing is done to

remove wear. Cylinder head is cleaned by removing

carbon and rust from the head, valve and cylinder

block. The valve is grinded to proper finish and

valve seat is lapped. The damaged piston is replaced

by anew one. The weared crankshaft is ground so that

ovality and taper are within permissible limits. The

thorough cleaning of engine parts follows

overhauling, and then the crank shaft is coated with

recommended lubricant and carefully placed. Timing

gears, sprockets, chains etc. are aligned and

installed. Piston-connecting rod assemblies are

installed. Cylinder head is assembled and then valve

lifters and push rods are then placed followed by

rocker arms. Water pump and outlet neck are then

fixed into the block.

ASOK LEYLAND TECHNICAL DATAS

1)ORDINARY PISTON

Compression ring closed gap

0.508 to 0.686 (20 to 27 thou)

Compression side clearance in groove

0.064 to 0.114 (2 ½ to 4 ½)

Compression scraper ring closed gap

0.381 to 0.559 (15.22)

Compression side clearance

0.064 to 0.114 (2 ½ to 4 ½)

2) ALFIN PISTON

Compression ring closed gap

0.457 TO 0.635(18 to 25)

Compression side clearance in groove

0.076 to 0.127 (3 to 5)

Compression scraper ring closed gap is same as ordinary piston

Renew all rings when closed gap exceeds 80 thou and side clearance exceeds 15 thou

3) PISTONCylinder bore to piston diametral clearance

0.203 to 0.254 (8 to 10)

Distance from piston crown to cylinder block top surface

0.025 to 0.356(1-14)

4)CAM SHAFTRenew all bearings when diametral clearance exceeds end play of 0.102 to 0.2039(4 to 8)

Maximum end play (10) to be adjusted by SHIM

Renew camshaft when the difference in dimension of base circle diameter and cam nose radius is 7.44mm(0.293”)

5)TAPPET CLEARANCEInlet and exhaust 0.508(20)

6)CYLINDER LINER Height of cylinder liner above the block surface (24to 36)

Maximum permissible taper or ovality (2)

7)TIMING GEARSPermissible backlash 0.102 to 0.152 (4 to 6 )

Initial diametral clearance between idler gear and brush (2 to 3)

End float between thrust washer and idler gear (2 ½ to 9 ½)

Renew thrust washer when end float exceeds 0.305(12)

8) CRANK SHAFTAxial play of crank shaft (2 to 10)

Diametral clearance between main bearing and main journal (1 ½ to 4)

Maximum (7)

3.UNIT

In this section it undertakes maintenance works of

power transmission systems which includespneumatic

braking, steering, propeller shafts, gear

box,differential power transmission unit, front and

rear axles.

The teeth of all gears are checked and the needle

bearing if worn out is replaced. The clutchand the

sleeve are checked for wear and the splines are checked

for wear. Thegear parts are then assembled, reverse

gear first and then the second, third, fourth gears in

correct order with adequate provision for the washer and

slide needle.

The repairing of gear boxes take place, gears which

have either worn out or gone out of alignment are

brought to this section, where it is cleaned

thoroughly and then the entire gear box is dismantled

and the parts which are damaged beyond recovery are

replaced and the parts that can be repaired are done

so. After which the parts are assembled back together

using sufficient lubricants for each set of gears.

Propeller shafts are a different section within the

Unit, the old buses used a two propeller shaft

system. Now a three shaft system is used, where there

is a front shaft,a central shaft and a rear shaft.

Which are attached using universal joints. The shafts

are checked for bends and straightened out.

Differential is fitted in the rear axle and is a

mechanism in which one wheelis allowed to run faster or

slower than the second rear wheel as and when required.

The systems used in the buses are of crown and pinion

arrangement. This department is handled by technical

staff specializing in it. These gears are very prone

to wear and tear, the transmission system requires

constant maintenance as it is needed for high

efficient power transmission. Each toothon crown

wheelpinion, sun and star pinion is inspected for any

broken teeth.

Front and rear axles are also repaired in the Unit.

The part which gets damaged more quickly are the

bearings in the axle which are replaced with new

bearings and then sent to be fit back in the bus.

Pneumatic system i.e., it works on compressed air

is used as the braking system in the buses. This

department is isolated from all other departments and

have specialized technical staff and they do the

repairs for the compressor, distribution system. They

repair it and on the pressure checking system they

check the condition. There are two models of air

braking system. OVERHAULING OF GEAR BOX

Gearbox is fitted after clutch assembly and has a

set of gears, which can be engaged to increase

driving torque to cope up road and load condition of

vehicle. The teeth of all gears are checked & the

needle bearing if worn out is replaced. The dog

clutch and the sleeve are checked for pitted teeth

and the splines are checked for wear. The gear parts

are then assembled, reverse gear first and then the

second, third, fourth gears in correct order with

adequate provision for the washer and slide needle.

OVERHAULING OF PROPELLER SHAFT

The propeller shaft is used to transmit power

from the gear box to the rear axle.Keeping the

propeller shaft on the v-block and with a dial gauge

check the propellershaft for bends, this should not

exceed 2mm.If more, it is straightened out using

hydraulic press. The cross pin and bearing cap

ischecked for any sign of wear placed with a new set

if required. The propeller shaft isthen fixed back to

the gear box flange and differential flange taking

care that theyyokes of the propeller shaft are

properly fitted.

PROPELLER SHAFT LENGTH

1) LL 2P rearF 158cmR 155cm/165

2) LL 3P setF 97cmC 130cmR 126cm

3) LLBS II SWB 2P setF 155 cmR 100cm

4) LLBS II 3P setF 109cmC 155cmR 130cm/133cm

5) JNT30cm

6) TATA / LL 12m 3P set F 158cm

C 160cm

R 112cm

7) T C (short)F 38cm

C 130cm

R 112cm

8) T C (long)F 96cm

C 130cm

R 118cm

9) TATA BS II 3P set

F 83cm

C 130cm

R 118cm

OVERHAULING OF DIFFERENTIAL

Differential is fitted in the rear axel housing

and is a mechanism in which one wheelis allowed to

run faster or slower than the second rear wheel as

and when required.Each tooth is inspected minutely

for any pitting or broken teeth on crown wheelpinion,

sun and star pinion and if worn out is replaced. The

thrust washer and pinionbearing are also checked for

damages. Checking the back lash of the sun pinion

with astar pinion using dial gauge does assembly of

the differential. The pinion is assembledin oil seal

with new oil seal in reverse order and after washing

the differential castingthe pinion is inserted. The

differential assembly is then fixed back in axle

housingwith new gasket and nuts are all tight.

PARTS

1)CROWN PARTS

TEETH 35, 37, 41

BOLT

TATA-8,16

LEYLAND-16,12

PINION TEETH

FOR CROWN TEETH(35,37) -6TEETH

FOR CROWN TEETH(41) - 7 TEETH

2 CAGE

2 SUN GEAR

4 STAR GEAR

1 TUNION/SPIDER

2 THRUSH WASHER BIG

1 THRUSH WASHER SMALL

2 SIDE BEARING

2 TAPER BEARING

1 DISTANCE PIECE

PINION BODY

1 SPACER (IN LEYLAND)

FLANGE

PINION NUT

SPLIT PIN

OIL SEAL

PILOT BEARING

PINION TORQUE RANGE – 350 POUND

2) SHIM

Shim is used to describe the teeth thickness of crown and pinion

Calculation for shim

FIXED NO: 2.657(LEYLAND)

PINION NO: 7.750

BODY NO: 10.380

SHIM=(FIXED NO + PINION NO) – BODY NO

DIAMETER OF SHIM IS 27

PLAY RATE IN LEYLAND – 12 TO 20 THOU

1 THOU =1 inch/1000

PLAY RATE IN TATA -8 TO 12 THOU

BODY ASSEMBLY TORQUE RANGE 250 POUND

PROVIDE OIL GRADE 140

4. FUEL INJECTION SECTION

The injection system consists of fuel tank, fuel

feed pump, fuel injection pump, fuelfilter, fuel

injection nozzle and a governor. The injection pump

pumps meteredquantity of fuel to all injectors and

ands should build enough pressure so that dieselgets

sprayed in fine atomized form. To increase or

decrease the quantity of the fuel a helix is cut on

top of the plunger. The alignment of this helix

determines the quantityf fuel pumped.The delivery

valve keeps the injector pipe always filled up with

diesel oil. This valvesits back on its seat after the

pumping operation and the space vacated by the

pistonmade on delivery valve is taken up by the

diesel oil under pressure in the pipe. These engines

are equipped with governors to ensure that engine

doesn’t pick up speedwhen there is no load, as the

engine speed is dependent on quantity of fuel

supplied.

The diesel is fed into the injection pump in two

ways namely gravity feed and forcedfeed. The

injection pump must give equal quantity of fuel to

all cylinders and thesupply should commence and stop

at fixed degree of crank angle both of which

arechecked and adjusted on the injection pump test

bench. Phasing of injection pump isdone by mounting

the injection pump on the test bench and noting the

angle of delivery on its flywheel.Fuel filter is

necessary to supply clean fuel otherwise dust will

wear the plunger andbarrel. Primary filter made of

felt and secondary filter made of paper, which needs

tobe replaced at regular intervals, are highly

recommended.Injectors are used to spray diesel in

fine atomized state before the piston reaches TDCin

compression stroke. Injectors should commence and cut

off fuel rapidly and at thesame time should not

dribble. Facilities have been provided for suitable

testing of theinjectors, which includes

i. Leak off test: The injector tester is worked up

to build a pressure of 150 atms,which is kept for

10 seconds (without spraying).In case there is a

drop inpressure the body seat and the needle is

lapped.

ii. Spray test: The injector is fixed up as done

earlier and pressure gauge isdisconnected by

closing the valve. The tester is worked up four

times and asecond and the spray pattern is noted.

If the spray pattern is in the form of astream or

jet, the needle and the nozzle body seat requires

grinding.

Nozzle and needle come in as one unit with the

needle circular in shape having a taperend while

nozzle body has fine finish. Where the needle can

slide there is a circulargroove called pressure

chamber at the lower end connected to the oil gallery

in the body though a drilled hole and it is from this

hole diesel oil reaches the pressurechamber and lifts

the nozzle valve of its seat and gets sprayed in

atomized form.

5.RETRIVALIn this department they deal with the maintenance

and reconditioning of the clutch assembly. The clutch

plate is checked for wear of the clutch lining wear.

Clutch is a coupling fitted immediately after the

engine in between the gear box to disconnect engine

power to gear box to change gear, to stop the vehicle

as well as to allow the engine to take up load

gradually. Visual inspection of friction flywheel

surface is done for any scoring mark, heat crack and

the pilot bearing play is checked by inserting a

finger in the bearing and feeling the play. Clutch

plate is checked for wear of the clutch lining wear.

Cracks in the clutch plate steel disc are also

checked. The pressure plate is checked for heat

damages, cracks and flatness using a steel rule of

feeler gauge. After cleaning all the parts and

checking for any undue play in the linkage, the parts

are assembled.

TATA CLUTCH TECHNICAL DATAS

Pressure plate diameter=310mm

Finger=4nos

Spring=16nos

Return spring=4nos

Push type

TATA FOUR FINGER/TC

Pressure plate=330mm

Spring=16nos

Finger=4nos

Return spring=4nos

TATA THREE FINGER T/C

Pressure plate=330mm

Spring=9nos

Finger=3nos

Withdraw plate=1nos

Return spring=1nos

TATA-1616 (BS-3 ENGINE)

Pressure plate dia=350mm

Spring=21

12big,9small

Finger=3nos

Release bearing=1nos

Roll type

Tapered cover

5.ELECTRICAL SECTION

In the electrical department, they deal with the

reconditioning work of alternators and starter

motors. Alternators are present in many different

models depending upon the engine manufacturer. There

are two types of starters repaired in this section

one is the old type using a solenoid. The starter has

a main housing, pinion gear, armature, field coils

with brushes and a solenoid. The engine oil at times

leaks into the starter motor and thus it stops

running. The parts except the casing are replaced.

Alternator is used to recharge the battery using the

engine power, it is a generator. It is given to the

engine using a belt. The coil in the alternator is

replaced and reconditioned for use in the future.

6. SUSPENSION SECTION & VEHICLE OVERHAULING

SECTION

The automobile chassis is mounted on the axles, not

direct but through some for m of springs. This is

done to prevent road shocks form being transmitted to

the vehiclecomponents, safe guard the occupants from

road shocks and to preserve the stabilityof vehicle

in pitching or rolling while in motion. All the parts

which perform thefunction of isolating the automobile

from the road shocks are collectively

calledsuspension systems. The buses here commonly use

the semi-elliptic steel leaf springvariety. These are

selected for their excellent durability and elastic

capability.The spring consists of a number of leaves

called blades. All t he blades are boundtogether by

means of steel straps. The spring is supported on the

axle, front or rear bymeans of a v-belt. One end of

the spring is mounted on the frame with a simple

pinwhile on the other end connection is made with a

shackle. When the vehicle comesacross a projection on

the road surface, the wheel moves up deflecting the

spring, thischanges the length between the spring

eyes. If both the ends are fixed the spring willnot

be able to accommodate this change of length. This is

provided by means of ashackle, which gives a flexible

connection.

REPAIR AND MAINTENANCE OF SUSPENSION SYSTEMS

After prolonged us or over loading, spring

assembly gets flattened or one or two of itsleaves

get broken. The centre bolt is then removed ant the

broken leaf is dismantledand replaced with the new

one. The rubber bushes, which are used to hinge

thesuspension systems to the chassis, are greased and

are replaced if these are worn out.

The Chassis frame supports the load of the vehicle

and provides connecting link between frame and rear

axle to withstand stresses caused due to cornering,

breaking,sudden acceleration or bad road

conditions.Rough use of vehicle may cause the chassis

to crack, bent and dislocate its weldedparts. The

loose and distorted rivets are removed and new heated

rivets are fixed. Redoxide paint is s prayed on the

chassis frame to prevent corrosion. If the chassis

hasmet with an accident, it should be straightened

out and the alignment checked, failingwhich, running

the bent chassis will make the steering hard and eat

away the tyre.Defects in the external body of the

bus, which is made of sheet metal, are checked andthe

necessary corrective steps are taken. These include

providing fresh coat of paint tothe rusted parts.

Distorted portions of the sheet metal are then

sharpened out. Newones replace the worn out furniture

if necessary or the existing ones are repaired.

BODY BUILDING DEPARTMENT

The chassis coming from the factories is brought

to this section and the body is builtthrough a

continuous process of welding, carpentry, sheet metal

and painting. Thisdepartment essentially deals with

the assembly of the interior and the exterior parts

of the bus with the engine, gear parts etc. being

bought from other automobilecompanies like TATA and

ASHOK LEYLAND.In the welding section the steel

structure is welded to the chassis. To this frame

work wooden attachments consisting of the platform,

the foot board and the wooden partsby the window sill

are fixed. The skeleton frame work is then covered

using the sheetmetal section. Care is taken to ensure

a clean and stable fit. Nuts, bolts along

withadditional fixtures are provided wherever

necessary to provide compactness to thestructure.

Painting glass fixing, seating arrangements and other

finishing touches aredone to ready out the interior

and exterior portions.

CONCLUSION

The industrial training to KSRTC gave us an

insight into the operation of industry and also the

various operations done in various departments.The

implant training we have done in KSRTC Central Works

provided as with great exposure in the field of

automotive engineering and in the management of

industrial activities taking place in an organized

manner. The most efficient way of work done is also

studied from that industry. That is the great

experience of all the group members.