HMT tractor division file

A TRAINING REPORT AT

HINDUSTAN MACHINE TOOLS (HMT)

(FROM JULY, 2013 TO AUGUST, 2013)

Submitted in partial fulfillment of the requirement for the award of degree of

“Bachelor of Degree in Mechanical Engineering”

SUBMITTED TO:- SUBMITTED BY:

ACKNOWLEDGEMENT

Everything is difficult before it become easy. This tradition comes through because of

certain people who by their pioneering efforts leave indelible mark on other.

Industrial training plays an important role in broadening the practical outlook of an

engineering student. In this matter we are fortunate enough to avail this opportunity by

having undergone six weeks industrial training at H.M.T. limited, Pinjore.

We are highly thankful to respected Mr. BHUSHAN SHARMA {TPO, Engg.

Department} and Mr. DHEERAJ CHHABRA {HOD, Mechanical Department} for their

indigenous support & instilling me the true basics of successful organization.

The training was an experience of lifetime I clear most of the ambiguities regarding the

concept of manufacturing I had gained a lot from this training on academics as well as

personnel ground.

In the end we feel completing this file has open new prospects and target fields for us that

I would love to achieve to provide the helping hand in shaping my country’s progress and

self-dependence.

i

PREFACE

First of all I thanked the management of H.M.T. ltd., India, that during my engineering

(mechanical), an opportunity was given to me to impart my 4th

semester training in

industrial organization and gained knowledge on different topics of tractor. I had gained

maximum knowledge about it during this span of training.

I also thanked my colleagues of their cooperation to learn the various topics through

useful discussion in the industrial class. Suitable number of problem had been solved to

help understand the theory/practical.

Last but not the least I wish to express my gratitude to Mr. Radha Raman, training

incharge HMT Ltd. For their valuable guidance and helpful advices during my project.

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TABLE OF CONTENTS

TEXT NAME PAGE NO.

1. Company profile 1

2. Tractor division 2

3. Light machine shop 7

4. Engine shop 11

5. Heavy machine shop 13

6. New engine shop 20

7. Engine assembly and testing 23

8. Heat treatment 40

9. Conclusion 44

10. Reference 45

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LIST OF FIGURES

Fig

no.

Figure name Page

2.1 Model of HMT tractor 2

2.2 Cutting action on milling machine 5

3.1 Raw material for gears. 9

3.2 Hobbing operations in spindle making. 10

4.1 First stage of connecting rod 11

4.2 Horizontal milling machine. 12

4.3 Intermediate stage of connecting rod. 12

5.1 Gear box 15

6.1 Bottom face of crank case 20

6.2 Fixture of making crank case 20

6.3 Crank case 21

6.4 First stage of cylinder head 21

6.5 Final stage of cylinder head 22

7.1 Assembly line 23

7.2 Transmission system. 25

7.3 Layout Of assembly plant 26

7.4 Differential design 27

7.5 Differential system 28

7.6 Rear covers assembly 29

7.7 Gear box assembly 31

7.8 Intermediate Shaft 31

7.9 Lay Shaft 32

7.10 Working of gear box 33

7.11 Meshing of gears 33

7.12 Reverse gear 34

7.13 Single clutch 37

7.14 Double clutch 38

iv

CHAPTER-1

1.1 COMPANY PROFILE

In 1949 the idea of public sector tools was commissioned to be a corner stone for

the government’s industrial development plans. This led to the birth of HINDUSTAN

MACHINE TOOLS at Bangalore in 1953 which started a single machine tool factory to

produce lathes at Bangalore, in collaboration with M/S Oerlikon of Switzerland.

Next, the company widened its product range beyond lathes by entering into technical

collaboration with other international leaders in machine tools such as Fritz Werner,

Herman Kolb etc.

The second machine tool unit was set up in Bangalore in 1961making use of

company’s own resources. watch factory was set up in Bangalore in 1962 to produce

hand watches.

The third machine tool unit was set up in 1963at Pinjore, Haryana to produce

milling machines. In next few years, machine tools unit were set up at Kalamessary in

Kerala and Hyderabad. The printing machinery division was attached to the machine tool

factory at Kalamessary to qualities printing machines.

HMT’s tractor business commenced its operations in Pinjore in 1971 in technical

collaboration with M/S MOTOKOV, Czechoslovakia because of priority given to the

agriculture in the national development plan and to take advantage of green revolution.

HMT started the operation with the manufacture of 25HP tractors. Over the years, it has

developed tractors ranging from 25 HP to 75 HP.

The unit Hyderabad began to make lamps and lamp making machinery in 1973 to

cater to the growing needs of rural. This was followed by producing automatic watches.

A third watch factory was established in Srinagar to manufacture hand wound watches

for men. In 1975, the company took over the machine tool corporation of India’s unit in

Ajmer, Rajasthan and its name was changed to HMT Limited.

1

CHAPTER-2

2.1 TRACTOR DIVISION

HMT established tractor plant in Pinjore in 1971to provide impetus to the country’s

green revolution. To begin with, it started assembly of 25 HP tractors. Pinjore was

selected for the project because it was within the high density crop-producing region

which provides immediate market in the vicinity.

Initially, the tractors were assembled from imported CKD/SKD packs. Production

facilities were simultaneously established to reduce the imported contents with the result

that the model was fully indigenized within a short span of five years.

At present, HMT manufactures tractors in 25, 35, 40, 49, 65 and 75 HP ranges. Out of

these 35, 40, 49, 65 and 75 HP tractors are designed in-house. All HMT tractors are

Bharat term-III certified.

Fig 2.1 model of hmt tractor

2

2.1.1 Exports

HMT has received and executed export orders from countries like USA, Italy, Sri

Lanka, Australia, Nepal, etc. the machines and tractors for export comply with the strict

international standards and environment safety. These standards are also incorporated in

machines and tractors for domestic sales.

2.2 TRAINING CENTRE

2.2.1 Structure of training centre:-

Training centre is divided into 7 sections:-

a) Turning section

b) Fitting section

c) Milling section

d) Tractor section

e) Grinding section

f) Drilling section

g) Shaping section

a) Turning section:-

In turning section we have learned about the lathe machine which is mother of all

machines and play a basic role in mechanical line. Lathe is also known as “complete

machine”. The single machine can do number of operation.

1. Facing

2. Drilling

3. Boring

4. Threading

5. Knurling

3

b) Fitting section:-

It is a very important work in engg. In fitting shop unwanted material is removed

with the help of hand tools. It is done for mating, repair and manufacturing purposes. The

person working in fitting shop is called a fitter. Commonly used tools are hacksaw, files,

chisels etc.

Tools used in fitting shop:-

1. Clamping tools

2. Measuring and marking tools

3. Cutting tools

4. Striking tools

5. Drilling tools

c) Milling section:-

Milling machines were basically developed to machine flat surfaces. But the present

machines can machine flat, contoured and helical surfaces, cut gears and do various other

jobs. Due to this milling machine is one of the most useful and necessary machine tools

found on the shop and it ranks next to the lathe in importance. These machines are

designed to hold and rotate milling cutter or cutters, hold the work piece and feed the

work piece to the milling cutter in one several directions.

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Fig 2.2 cutting action on milling machine

The milling machine generally consists of:-

1. Worktable

2. Saddle

3. Knee

4. Head

5. Over arm

d) Drilling section:-

Hole making is among the most important operation in manufacturing. In automobile

engine production, the cost of hole making is one of the largest machine cost. Drilling is a

major and common machining process. They are capable of producing relatively deep

holes. The various types of drilling machines present in this section are:-

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1. Simple drilling machine

2. Radial drilling machine

e) Shaping section:-

It is used to produce flat surface or grooves by the movement of shaping tools over

the work piece. These machines are the product of HMT itself. In these machines a quick

return mechanism is used. By doing so it saves the idle time and increase the production.

In this machine the work piece is fixed in one position and tool moves.

f) Tractor section:-

In tractor section we have seen a assemble tractor and see all the parts of tractor under the

guide of tractor division incharge. We have studied deeply of lifting mechanism, gear

box, crank case, in tractor division.

6

CHAPTER-3

3.1 LIGHT MACHINE SHOP

As the name shows all the light parts of tractors such as differential housing, power

take off shafts, splined shafts, gear, rear wheel driving hubs, portal shafts, main

transmission shafts etc. are machined here. Different operations such as turning, grinding,

hobbling, broaching, milling, drilling, boring, reaming, threading etc. are performed here

two type of materials are uses in light machine shop.

1. Rolled steel (in the form of bars for the manufacture of shafts).

2. Forged steel (in the form of circular pallets for the manufacture of gear).

Light machine shop is divided into following sections.

Cutting section

Turning section

Auto and miscellaneous

Tool room

Production planing and tooling (ppt)

3.1.1 Bar cutting section

The bar cutting section deals with cutting, facing and centering of the bars and pallets to

desired diameter and thickness with the help of different machines. The different

machines in bar cutting section are.

Bend saw

Circular saw

Power hacksaw

Column drill

7.

3.1.2 Milling machine:-

In these machines, bend saw is more accurate and efficient machine and also the

only one fully automatic saw. The circular saws are capable of cutting the bars of

diameter even more then 200-300mm. After bar cutting facing and centering is done with

the help of vertical column drilling and milling machines. These bar and pallets are then

transported to the turning section of the LMS (Light Machine Shop).

3.1.3 Turning section:-

In this section the centered and faced material is subjected to various turning operation to

form various gears and shafts. The operations undertaken here initially produce a gear

and shafts blanks which are then machined into their respective forms according to their

function. The series of operations performed in this section are as under:

1. Gear blank formation

2. Gear cutting

3. Gear shaving

3.1.4 Tool room:-

Tool room is the one of sensitive machining area in the LMS. It mainly deals with the

production of JIG & FIXTURE. It is well equipped with highly precised machines for

instrument calibration and setting them to their best level of accuracy. The various

machines of the tool room are as under:

Double column jig boring

Mikromat (german technology).

Hydroptic (swiss technology).

Mitsui-seiki (japanese technology).

3.1.5 S-40 Studer CNC grinding machine:-

The important aspect of all the machines in the tool room is their temperature sensitivity.

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3.6 PRODUCTION PLANNING AND TOOLING:-

The area of LMS is well equipped with the machines that are used to build the cutting

edge of the tools. The cutting tools are subjected to inspection to measure the inaccuracy

in their geometry.

The tools are then grinded on highly précised and properly indexed grinding machines to

obtain their cutting edges. This machining operation requires skill as the overall quality

of the component manufactured depends on the cutting tool used.

The PPT section is well equipped with gauges, broaches, hobs, thread rolls, reamers, taps

and sundry tools, turning and milling cutters, Gleason cutters.

Fig 3.1 Raw material for gears.

These above are the raw material used for the making gears. These all are casted and

forged in forging section. Forging is done so that material cost is to be maintained.

3.7 MACHINES IN THIS SECTION:-

Auto fay: - It is a special purpose lathe designed by Jones and Lampson of America.

Copying lathe: - it is used for copy turning of long shafts. a cutting tool moving

hydraulically generated the profile of same shape as that of masterpiece. main

features of this lathe are:

Automatic multi cycle copying

Maximum performance and minimum maintenance

9

3.8 THREAD ROLLING MACHINE:-

It is a machine having two master rollers on which threads are present. Both rollers

are moving in clockwise direction. Job is inserted between two rollers for cutting of

threads. There is affixed time period for the roller for operator can fix the thread cutting.

In the back these threads are attached with the Oldham’s couplings for lateral

misalignment.

3.9 HOBBING:-

It is done on single purpose hobbling m/c. So far as design is concerned there are two

basic types i.e. H2 work spindle and Vertical work spindles. The Vertical type is more

widely used. Multiple spindle m/c is used when production requirements are high.

The job spindle has two adjustments 1st the tool head is mounted on a swivel base so that

the axis of the hob spindle may be set at an angle to axis of the work spindle. The angle

depend upon the helix angle of the kind of gear being cut and second, the hob spindle

may be adjusted axially as a means of distributing wear on the tools.

Fig 3.2 hobbing operations in spindle making.

10

CHAPTER-4

4.1 ENGINE SHOP

In engine shop there are manufacturing of the entire components which is being

used in engine assembly. We have seen all the machining process which are used to made

a particular component for example connecting rod takes 15 different machines to be

fully completed.

Fig 4.1 First stage of connecting rod.

This is the first state after casting in this fig 4.1 only facing is being done. Facing is done

thrice time to fully complete the connecting rod.

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Fig 4.2 Horizontal milling machine.

Above figure is of horizontal milling machine which is used to cut the connecting rod to

two basic halves one is the main connecting rod and another is the clamp which clamp

the connecting rod into crank shaft in crank case.

Fig 4.3 Intermediate stage of connecting rod.

This is the intermediate step for connecting rod after cutting to two halves. Below is the

second part that is clamp.

12

CHAPTER-5

5.1 HEAVY MACHINE SHOP

It is a part of tractor division in which two types of heavy casting (Gear box and

MT housing) are machined and some other components are also manufactured. In this

shop the machines are arranged according to the sequence of operation and job moves

from one machine to another in series. This type of layout results in lerrer amount

Material Handling. The machines used basically are special purpose machines (SPM)

which are manufactured and for a particular operation. The various types of machines

present in this shop are:

Semi-Automatic Machines:-

Radial Drilling Machine.

Horizontal Milling Machine.

Vertical Milling Machine.

Boring Machine.

Inclined Boring Machine.

Dual Milling Machine.

Turret Lathe Machine.

Two Way Multiple Drilling Machine.

Thread Milling Machine.

Computer Numerical Control (CNC):-

Horizontal Milling Centre 630.

5.1.1 GEARBOX:-

Gearbox is that part of tractor which is mounted in the tractor between the Engine and

Main Transmission Housing. Speed and Torque of the Tractor as per its operating load

condition.

The type of Gearbox used in the tractor is SLIDING MESH GEARBOX. In the Gearbox

the Power comes from engine to the clutch shaft and hence to the clutch gear which is.

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always in mesh with a gear on the lay shaft. All the gears on the lay shaft are fixed to it

and as such all the time rotating when the engine is running and clutch is engaged. The

gears present on the splined shaft are free to slide on it.

Following are the main components of gearbox:-

(a) Input shaft assembly.

(b) Output shaft assembly.

(c) Lay shaft assembly.

(d) Intermediate shaft assembly.

(e) Clutch Actuator guide assembly.

(f) Gears.

(g) Gearbox housing.

(h) Shifter rods.

(i) Shifter fork.

(j) Bearings.

(k) Fasteners, gaskets and spacers.

These gears are arranged in such a manner that when they mesh with various other gears

they give different amount of Speed and Torque. These assemblies of gears and shafts are

mounted on the gearbox casting with the bearing, so that all the thrust of the gearbox

comes on the casting and the gearbox remains strong and can take all of the load and

thrust of the fear without any distortion.

After the manufacturing of the casting of gearbox comes in HMS shop for the maching

operations, here many operations like Drilling, Grooving, Milling, and Facing and many

other operations are done on the gearbox.

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Fig 5.1 Gear box

The various operations carried out on the GEARBOX Housing as it flows through the

production line are:-

(a) Marking.

(b) Face Milling.

(c) Drilling.

(d) Face Milling.

(e) Boring.

(f) Drilling.

(g) Finish Boring.

(h) Tapping.

(i) Fitting.

(j) Washing.

(k) Grinding.

(l) Inspection

5.1.2 Main transmission housing:-

The main transmission housing accommodates the differential which transmits the power

coming from the gearbox to the half axles and further on the rear wheels.

15

When the tractor is taking a turn the outer wheel will have to travel greater distance as

compared to the inner wheel at the same time.

Therefore if the Tractor has a solid rear axle only and no other device will be tendency

for the wheel to skid. Hence if the wheel skidding is to be avoided some mechanisms

must be incorporated in the rear axle, which should reduce the speed of the inner wheel,

and increase the speed of the outer wheel when taking a turn, the device which serves the

above function is termed as differential.

The various operations carried out on the MT Housing as it flow through the production

line:

(a) Marking: - First of all the making of reference line with respective to the bores on

the MT Housing Casing is done before the machining operation. It takes place on

the surface table. The MT Housing is marked for the identification & visualizing

of the machining depth and the right position of the bores and drills on every six

sides of the MT Housing.

(b) Face Milling: - Milling of the top and bottom face is done on the duplex Milling

Machine. The diameter of the face cutter is almost equal to the width of the area of

work piece to be machined.

(c) Drilling: - The Drilling of the 2 location holes on the bottom face of the MT

Housing is done on the radial drilling machine. The location holes are drilled in

order to clamp the work piece on the fixture and also acts as reference holes for the

other dimensions.

(d) Face Milling: - The Milling of the left and right face of the MT Housing is done on

the Duplex Milling machine. On this machines where are two spindles and the

machining of the both faces is done correspondingly.

(e) Face Milling: - The MT Housing is clamped on the bed with help of the location

holes and the milling of the front and rear face is done.

(f) Boring: - the boring operation is carried out on the left and right side of the MT

Housing.

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(g) Drilling: - The drilling operation is carried on the front and rear sides of the MT

Housing. The operation is carried out on two Way Multiple Drilling machine.

Each spindle of various drills rotates with varying speeds.

Drilling: - The Drilling operation is carried on the left and right side of the MT

Housing on the Multiple Drilling Machine.

(h) Drilling: - Drilling is done on the sides of the bores on the radial drilling machine

with the help of fixture.

(i) Finish Boring: - The final boring is done on the MT Housing.

(j) Tapping: - Tapping of the holes is done on the Radial drilling machine with the use

of tapping tool.

(k) Washing: - The cleaning of the work piece is done by using hot water (heated at

60°C) and casting soda to remove oiliness and chips.

(l) Grinding: - The internal grinding is carried out as the last machining operation.

(m) Inspection: - At last the inspection is done.

Other components manufactured in HMS area:

(A) Steering shaft bush

(B) Left hand shaft bush

(C) Break Drum

(D) Break Drum Cover

(E) Front wheel hub

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5.1.3 HORIZONTAL MACHINING CENTRE (HMC)-500:-

HMC-500 is a fully automatic CNC horizontal machining centre with three linear

axis, rotary pallet index base, twin pallet changer and tool changing capability. This

machining centre has been designed to automatically change tools for Milling, Drilling,

tapping, Boring, Reaming in fact perform most type of machining operations all in one

handling of the work piece. Under the guidance of the CNC the tool is positioned at any

desired point or it is made to follow any contour for the machining operations. Twin

pallet changer automatically changes the required pallet on the index base.

5.1.4 HMS:-

All heavy castings of Tractor is machined in this shop with the help of variety of

Special Purpose Machine (SPM). In addition, Facilities of this shop include General

Purpose Turning Machine, drilling and milling machines. About 20 SPM and 30 GPM

are installed in a covered area of 47,000 sq. Ft. At a cost of 20 million, 2600 tones of

castings are machined every year on a two-shift basis. In addition to the machining of

casting for the tractor, some jobs are also performed for SWARAJ MAZDA LIMITED.

The Heavy Machine Shop divided into five sections:-

Differential housing line

Rear cover Housing line

Gear box housing line

Cage & trumpet line

Brake Hogg line

All the work stations are highly equipped with modern machinery and equipment. Each

work station has a process layout i.e. the raw material is received at one end and the

finished component is dispatched from the other. The component is made to go through

final inspection before it is dispatched for assembly.

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The Material handling System in the H.M.S shop consists of hydraulic lift trucks, power

hoists, roller conveyors, overhead crane, fork lift trucks, bins etc. the shop has well

designed network of roller conveyors. The castings from the truck are loaded onto these

conveyors and the material travels to reach the respective line. At the end of each

conveyor a section for inspection has been made so as to make the component through

the inspection process. Each workstation is provided with a power hoist of 500Kg (load

carrying capacity). These are used to pick casting from conveyor and load them onto the

machine and vice versa. There is also a provision of a 2-ton carrying capacity overhead

crane in each section.

5.1.4.1 Types of Machines in H.M.S:-

Radial drilling machine.

Vertical milling machine

Horizontal machining

Simplex milling machine

Duplex milling machine

Lathe machine

Double end

T/W boring

Automatic lathe

SPM (Special Purpose Machine)

GPM (General Purpose Machine)

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CHAPTER-6

6.1 NEW ENGINE SHOP

In new engine shop two main types of part of tractor engine are made one is crank case of

two cylinder, three cylinder, four cylinder and second one is cylinder head.

Fig 6.1 bottom face of crank case

This is the bottom face of crank case which is faced by using special purpose milling

machine. The process which are being used for machining is

1. Marking – below is the fixture of making of three cylinder engine crank case

Fig 6.2 Fixture of making crank case

20

2. The second process is facing of one side by putting in fixture made on SPM

(special purpose machine).

3. Then taking reference we drill two guide holes. With the help of this guide holes

all the faces are finished by SPM machines.

Fig 6.3 crank case

Then all the holes are drill by drilling machines.

2nd

is the cylinder head

Below is the first stage of cylinder head after casting.

Fig 6.4 first stage of cylinder head

21

1. Firstly we have faced one face after marking and put into the fixture. As shown in

the figure.

Fig 6.5 stage of cylinder head final

2. Now with reference of this face we operate the entire next steps that are facing of

all the six faces.

3. Then drill is done.

4. At last inspection is done on marble which has high accuracy of flatness to given

correct testing.

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CHAPTER-7

ENGINE ASSEMBLY & TESTING

7.1 ENGINE ASSEMBLY

In this shop, whole of the engine is ready for the tractor assembly; various parts from

engine-manufactured section are brought in this section ad they are assembled to prepare

the whole engine. The entire engine i.e. 2522, 3522, 5022, 6522 are assembled here.

Engine assembly can be divided into 9 no. of steps as follows.

Step 1:-

First of all, the crank housing is washed in a special soap solution because after no. of

machining operation it contain drips, cutting oil dust particles, hence washing is

necessary. After washing the crank housing is dried by means of air jets.

Step 2:-

Now cylinder sleeves and cylinder lines are fitted in crank housing. The cylinder have

groove cut on the external periphery and in the groove a rubber ring is fixed which

Fig 7.1 assembly line

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Step 3:-

After this crank housing is mounted on a trolley and is brought to the engine assembly

line. 1st step is fixing of studs in the housing and then crank shaft mounted on the ribs of

the housing and the upper half of the bearing bracket supported the crank shaft gear. One

gear is power transmission gear with which another gear called, turning gear meshes, it

drives fuel injection pump. Power transmission gear also drives the camshaft gears; other

gear fixed above the crankshaft gear is idle gear, which drives oil lubricating pump gear.

Step 4:-

In this step, piston is inserted in the cylinder. Assembly of piston and connecting rod is

done repeatedly and then it is put in the cylinder rods big and holes are joined to

crankshaft by nuts and bolts. Lubricating gear pump is also assembled and then cam shaft

with gear is fixed in camshaft hole present in housing.

Step 5:-

After this fly wheel is mounted on the other end of the crankshaft and inside flywheel,

pressure plates and assembled clutch is fixed vices and tightened with the body of the

housing.

Step 6:-

Mow cylinder head is fixed on the top of the cylinder sleeve by stud cylinder head is

assembled in another assembly line. In cylinder head assembly 1st of all its machined

casting is thoroughly cleaned and washed. Now in it inlet valve guides, exhaust valve

guide with inlet and exhaust valve are fitted, injector with injector holder brush is also

fitted in cylinder head valve are pressed tightly against their seat with the help of high

tension coiled springs.

Step 7:-

After fixing the cylinder head on the crank housing, rocker arm, tapped and push rods

and assembly fitted for opening and closing of valves.

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Step 8:-

Now the engine is completely assembled by attaching fuel filter, oil filter, fuel injection

pump, injection lines, high tension void, starting motor, dynamo etc.

Fig 7.2 transmission system.

Assembly Shop is engaged in assembly of various models of HMT Tractors. The

assembly operation are divided into various operations and sub-assemblies such as

Engine Assembly, Transmission Assembly, Gear Box Assembly, Trumpet assembly,

Steering Assembly, Rear cover Assembly are send to main line for Tractor assembly. . In

main Tractor assembly line tractors are send to paint shop through overhead endless

chain rotating conveyor. It is supported from ceiling and has a fixed path to travel which

saves valuable floor space. The arrangement is such that lifting mechanism (with help of

hook) lowers down for loading and unloading of tractors. Following are main phase of

assembly: -

Differential assembly.

Rear cover assembly.

Gear box assembly.

Main line assembly.

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7.2 LAYOUT OF THE ASSEMBLY PLANT:-

Rear end

coverGear box

Trumplet steering

rocker brake pedal hanged by

Brake link fitment conveyor

differentialRear cover Gear box Trumpet fitment fitment fitment

Cage &Tail pinion

Lower link Tacklefitment loading

EngineCoupling

King pinfitment

Front axlefitment

ClutchFitment

Fig 7.3 Layout assembly plant

7.3 DIFFERENTIAL ASSEMBLY:-

Differential is a device that splits the engine torque two ways, allowing each output

to spin at a different speed. A gear system that transmits power from the drive shaft

through to the driving axels. It allows outer turning wheels to run faster than the inside

wheel when a car is turning. This prevents tire scrub and loss of stability

The first stage of assembly shop is Differential assembly. Before the various differential

parts such as Bull Pin shaft, differential cage etc. are assembled. The various sub-

assembly of parts listed above are performed in the sub-assembly units in the first unit .

The second unit assemblies the various differential cage parts. This constitute the

assembly of cross bar, planetary gear, planetary gear cover, crown wheel etc. Four star

gears are situated on the cross bar and two planet gears are engaged with this four star

gears are encompassed in the cage assy. The various bolt required making the assembly

of above parts and integral one are nutted using an pneumatic bolter gun.

26

After this, the differential cage is collected from the conveyor firstly fitted with the

necessary bearing races. Then the differential cage unit and the BP shaft is assembled,

making up a complete one unit. The trumpet Housing and the axles are assembled in a

different assembly shop and there on the whole unit along with the bull gears is

assembled to the differential cage . The assembly of differential housing is complete with

the assembly of lay shaft extension, the oil filter and the brake mechanism. This

completes the differential assembly.

7.3.1 Design of Differential:-

Fig 7.4 Differential design.

7.3.2 Various parts of Differential:-

Tail Pinion: - It transmits the power from the output shaft of gearbox to the crown

wheel.

27

Crown Wheel: - It gives housing to the cage assembly where differential action takes

place.

Differential Cage: - It gives housing to the spider kit i.e. cross, star, sun pinion.

Cross: Its remains fixed in the cage assembly and support the motion of the star pinion.

Star Pinion: - Distributes the power between sun pinion according to load applied by

them. Consist four star gears.

Sun Pinion: - Transmits power from star pinion to bull pinion shaft. consist four star

gears.

Bull Pinion shaft: - Gives power to the bull gear and bear the action of break.

Bull Gear:-Transmits power from bull pinion shaft to rear axle.

Rear Axle: - Transmits power from bull gear to rear wheel.

Differential Lock: - Differential lock is made on bull pinion shaft as a hollow shaft and

we provide an extra coupler assembly in the differential.

7.3.3 Working of differential system:-

Fig 7.5 Differential system

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When the power from the gear box transferred to the crown wheel through tail

pinion then whole differential action takes place. In cage-assy, there is a spider kit on

which cross, star pinion and sun pinion encompassed. The power between sun pinion

according to load applied by star pinion consisting of four star gears. Then the power

transmits from star pinion to bull pinion shaft. Further the bull pinion shaft connected to

bull gear and transmits power from bull pinion shaft to rear axle which is encompassed in

trumpet housing. From rear axle power transmits through rear wheels and thus whole

differential system works.

7.4 REAR COVER ASSEMBLY:-

Fig 7.6 Rear covers assembly

The second stage of assembly shop is the Rear Cover Assembly. Rear cover is upper

cover of differential. Rear cover contains whole of the hydraulic lifting system which

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incorporates the gear pump assembly which is also known as torque cylinder whose main

function is to lift the lifter hydraulically. Control valve is joined to rear cover of tractors

which controls the hydraulic living sensing. Hydraulic pump which pumps the hydraulic

oil supplies oil to the lift through action of control value. The direction control sector

adjust the height of lifter. Sensor tool used to sense the actual depth of ploughing tool

automatically. After that it is sent to the first stage where the whole differential is

assembled to the rear cover assembly and sent for further assembly.

Hydraulic Power Pack for Assembly Test Rig:-

In the test rig, proper working and maximum lift capacity of the lifter is checked

hydraulically. Oil AP80 is used in whole differential .The capacity of differential is 47

liter. Firstly the oil goes to the response valve then after filling the sensor valve it again

come back to the response valve. After filling the whole differential, the lifter lifts off and

checked the maximum capacity of lifter.

7.5 GEAR BOX ASSEMBLY:-

The Gear Box Assembly is the third stage of the assembly unit in which the gear box is

assembled. Firstly, the gear box housing is collected from the conveyor roller

successively. Parts such as the counter shafts, clutch shafts, main shaft along with the ball

bearings are assembled to the unit. There is separate sub unit assembling the planetary

cage and gears which is then attached to the gear box output shaft to obtain the duplex

speed ratios of the tractors.

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Fig 7.7 Gear box assembly

The assembled gearbox contains 4 forward gears. 1 reverse gear and 1.P.T.O shaft gear.

Further it contains two high and low shifting gears .Tractors have sliding type gearbox.

Fig 7.8 Intermediate Shaft

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Fig 7.9 Lay Shaft

7.5.1 Various types of parts used in gear box are:-

Input shaft

Output shaft

Intermediate shaft

Lay shaft

Clutch shaft

3 forks with rods

Sleeve

Planet carrier

Internal gear

7.5.2 Working in Gear Box:-

The Constant Mesh (CM) gear is rigidly fixed to the input shaft or clutch shaft. It remains

always connected to the drive gear (Also CM gear) of the lay shaft. Three other gears are

also rigidly fixed to the layout. They are the second speed gear, first speed gear and

reverse speed gear.

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Fig 7.10 Working of gear box .

Gears in neutral: - When the engine is running and clutch is engaged, the CM gear

drives the lay shaft gears. The lay shaft rotates opposite in direction of the clutch shaft.

Note that in neutral position, only the CM gear is connected to the CM gear of the lay

shaft. Other gears are free, and hence the transmission intermediate is not turning. The

vehicle is stationary.

First or Low speed gear: - By operating the gear shift lever, the larger gear on the

intermediate shaft is moved along the shaft to mesh in the first gear of the lay shaft. The

intermediate shaft turns in the same direction as the input shaft. Since the smaller lay

shaft gear is engaged with the larger intermediate shaft gear, a gear reduction of

approximately 3:1

Fig 7.11 Meshing of gears

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Second speed gear: - By operating the gearshift lever, the larger gear of the

intermediate shaft is de-engaged from the first gear of the lay shaft and then the smaller

gear of the input shaft is meshed with the second gear of the lay shaft. The intermediate

shaft turns in the same direction as the input shaft. A gear reduction of approximately 2:1

is obtained. The differential gear reduction increases this gear ratio to approximately 8:1.

Third, Top or High speed gear: - By operating the gear shift lever, the second

gear of the intermediate shaft and lay shaft are de-engaged and then the second and top

gear of the input shaft is forced axially against the CM gear of the input shaft. External

teeth on the input shaft gear mesh with the internal teeth in the second and top gear. The

intermediate shaft turns the input shaft and the gear ratio of 1:1 is obtained. The

differential reduction reduces a gear ratio of about 4:1 between the engine crankshaft and

the wheels.

Reverse Gear: - By operating the gear shift lever, the larger gear of the intermediate

shaft is meshed with the lever idler gear. The reverse idler gear is always in mesh with

the lay shaft reverse gear. Interposing the idler gear between the lay shaft reverse gear

and intermediate shaft bigger gear, the intermediate shaft in the direction opposite to that

of the input shaft. This reverses the rotation of the wheels so that the vehicle backs.

Fig 7.12 Reverse gear

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High/Low gear: - High/Low gear shifter enables to achieve either high torque-low

speed or low torque-high speed with the help of planet gear & carrier assembly.

High Gear: - Low torque-high speed is achieved when hi-low shifter is shifted in high

gear position. Coupling intermediate shaft and output shaft with the help of sleeve

transmits the power.

Low Gear: - High Torque-Low speed is achieved when hi-lo shifter in low gear

position. The power is transmitted to output shaft from intermediate shaft, planet gear and

carrier and assembly and sleeve. The Planet gear & Carrier assembly reduces the high

speed and subsequently torque is increased

7.6 BRAKE DRUM SUB – ASSEMBLY:-

In this sub-assembly, two brake discs are used. Steel balls are aligned properly

between the grooves of both the discs. With the help of springs, both the discs are

tightened and the small distance between discs due to steel balls. Now put the brake liner

on the both sides of discs in which one liner is attached to the bull pinion shaft (B.P.

shaft). So when brakes are applied, the brake discs extracted strongly which fixed the

brake liner to bull pinion shaft and causes the bull pinion shaft not to rotate. Thus motion

retards.

7.7 STEERING GEAR BOX, GEAR SHIFTING, BRAKE

ASSEMBLY:-

In this unit the sub assembly, the steering gear box, gear shift mechanism on gear

cover and the brake mechanism is assembled of these mentions sub assemblies, the brake

assembly is sent to the 1st stage of assembly and the steering gear box and the gear box

cover assembly is sent to the 3rd

stage assembly.

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7.8 CLUTCH:-

A clutch is a mechanical device that provides for the transmission of

power (and therefore usually motion) from one component (the driving member) to

another (the driven member) when engaged, but can be disengaged.

Clutches are used whenever the transmission of power or motion must be controlled

either in amount or over time (e.g., electric screwdrivers limit how much torque is

transmitted through use of a clutch; clutches control whether automobiles transmit engine

power to the wheels).

In the simplest application, clutches connect and disconnect two rotating shafts (drive

shafts or line shafts). In these devices, one shaft is typically attached to a motor or other

power unit (the driving member) while the other shaft (the driven member) provides

output power for work. While typically the motions involved are rotary, linear clutches

are also possible.

In a torque-controlled drill, for instance, one shaft is driven by a motor and the other

drives a drill chuck. The clutch connects the two shafts so that they may be locked

together and spin at the same speed (engaged), locked together but spinning at different

speeds (slipping), or unlocked and spinning at different speeds (disengaged).

There are two types of clutch:-

a) Single clutch

b) Double clutch

a) Single Clutch: A single disc or plate clutch consists of a clutch plate whose both

sides are faced with a frictional material. It is mounted on the hub which is free to

move axially along his splines of the driven shaft. The pressure plate is mounted

inside the clutch body which is bolted to the flywheel. Both the pressure plate and

the flywheel rotate with the engine crank shaft or the driving shaft. The pressure

plate pushes the clutch plate towards the flywheel by a set of strong springs which

are arranged radially inside the body.

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b) The three levers (also known as release levers or fingers) are carried on pivots

suspended from the case of the body. These are arranged in such a manner so that

the pressure plate moves away from the flywheel by the inward movement of a

trust bearing. The bearing is mounted upon a forked shaft and moves forward

when the clutch pedal is pressed.

When the clutch pedal is pressed down, its linkage forces the thrust release

bearing to move in towards the flywheel and pressing the longer ends of the levers

inward. The axial pressure exerted by the spring provides a frictional force in the

circumferential direction when the relative motion between the driving and driven

members tends to take place. If the torque due to this frictional force exceeds the

torque to be transmitted, then no slipping takes place and the power is transmitted

from the driving shaft to the driven shaft.

Fig 7.13 Single clutch

c) Double clutch: - Double clutching (also called double declutching) is a method of

shifting gears used primarily for vehicles with an unsynchronized manual

transmission, such as commercial trucks and specialty vehicles.

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d) With this method, instead of pushing the clutch in once and shifting directly to

another gear, the driver first engages the transmission in neutral before shifting to

the next gear. The clutch is pressed and released with each change.

Fig 7.14 Double clutch

7.9 ASSEMBLY OF GEAR BOX, DIFFERENTIAL HOUSING AND

OTHER ACCESSORIES:-

In the 5th

stage of assembly, the gear is mantled to the differential. Apart from this,

various other accessories such as foot board, battery clamp and other links such as

accelerator pedal link, clutch link, brake link etc are mantled in this stage.

7.10 ASSEMBLY OF ENGINE AND CLUTCH MECHANISM:-

This unit is separate 6th

stage of assembly in which the engines are received from the

stores and fitted with the clutch mechanism and lay been along with the counter weights.

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7.11 MAIN LINE ASSEMBLY:-

7.11.1Assembly of engine with the rest of transmission section:-

The assembly of the engine and the rest of transmission is done in the 7th

stage. In this

stage the whole of the chassis is formed as an integral unit. The various links and

mechanism between the engine and the gear box or differential is fastened together and

the whole integral unit is checked for its complete accessories etc. after the assembly of

this stage is complete, the assembled integrated unit is ready to pass through the paint

shop.

In all the stages of assembly, the skilled workers are used to accomplish all the stages of

assembly. But they are also held by the pneumatic bolt guns and the over head automatic

conveyors and the alarm conveyor etc to make their job easy .Also the whole of the

assembly is done on the Jigs or stands which is kept moving at a speed of about 7cm/min.

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CHAPTER-8

8.1 HEAT TREATMENT

Heat treatment shop plays a very important role in every industry. In

automobile industry all the gears and shafts need to be heat treated to impart desired

strength and increase life of the component. The H.T. Shop at PTL is equipped with

several gas carbonizing furnaces, quenching tanks, induction hardening machines and

shot blasting furnaces.

Heat Treatment is an operation or combination of operations involving heating and

cooling of metals and alloys in the solid state to produce certain desired properties. All

the treatment processes may be considered to consist of three main parts:

1. The heating of the metal to pre-determined temperature.

2. The Soaking of the metal at that temperature until the structure becomes uniform

throughout the mass.

3. The cooling of the metal at some pre-determined rate to cause the formation of

desirable structures within the metal/alloy for the desired purposes.

8.1.1 PURPOSES OF THE HEAT TREATMENT:-

Changes in properties result from the micro-structural changes in the material produced

by heat treatment operation. However, these serve one or more of the following purposes:

1. Improve Machinability.

2. Relieve Internal Stresses.

3. Improve mechanical properties such as Ductility, Strength, Hardness, Toughness

etc.

4. Change in Grain Size

5. Increase resistance to Heat and Corrosion

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8.1.2 Methods of heat treatment:-

Various methods depending upon the nature of Job i.e. it’s material, use etc are employed

for giving them heat treatment. The methods used are:

• Annealing

• Normalizing

• Hardening

• Quenching

• Tempering

• Case Hardening

a) Carburizing

b) Cyaniding

8.1.3 Annealing:-

Annealing means softening of the material by heating and cooling process. The cooling

stage may be performed by regulating the fall of the temperature in the furnace or by

buried the article in sand or lime, and quenching in oil or water, according to the material

being treated.

8.4 NORMALISING:-

In this process the material is heated steadily throughout its mass to just beyond the

critical temperature, and then withdrawn from the furnace and allowed to cool in still air.

With the normalizing process there is not soaking period, for the work is held at the

desired temperature for a period only sufficient to give uniformity throughout the mass.

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8.4.1 Main purposes of the Normalizing are:-

• To Remove the effects of previous overheating and thus place the material in good

mechanical condition.

• To remove the Internal Stresses caused by cooling from the molten state, by cold

working or by rough machining.

• To soften the work prior to further hardening or tempering.

8.5 HARDENING:-

The Operation of hardening is applied to all the tools and some important

machine parts intended for especially heavy duty service, as well as to all machine parts

made of alloy steel. Hardening of steels is done to increase the strength and wear

properties.

The process consists of:

Heating the steel to temperature above critical point,

Holding at this temperature for a considerable period,

Quenching (Rapid Cooling) in water, oil or molten sand bath.

8.6 QUENCHING:-

Quenching is the act of rapidly cooling the hot steel to harden the steel. Oil

is used when a slower cooling rate is desired. Oil Quenching results in Fumes, Spills, and

Sometimes a fire hazard.

8.7 TEMPERING:-

It is an operation to reduce the internal stress and brittleness. With plain carbon

steel, tempering operation consist in slowly heating the hardened material from room

temperature up to maximum of about 600C and then quenching in water or oil, the

temperature and length of soaking period being dependent in service requirement. Thus if

plain carbon steel is to be hard without any appreciable ductility, a temperature of about

150°C will be required.

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8.8 CASE HARDENING (CARBURISING):-

It is method of producing hard surface on steel. The steel used for this purpose

is usually a low carbon steel of about 0.15% carbon, which does not respond appreciable

to heat treatment. In course of the process, the outer layer is converted into high carbon

steel with a carbon content ranging from 0.9% to 1.2% carbon.

8.9 INDUCTION HEATING:-

It means the heating of ferrous metal by induced Electrical current prior to

the hardening quench. In this process, analysis of the surface steel is not changed, the

hardening being accomplished by an extremely rapid heating and quenching of the

wearing surface which has no effect on the interior core. The hardness obtained is the

same as obtained in conventional treatment and depends upon carbon content. The

heating effect is due to the induced eddy current in water or oil, the temperature and

length of soaking period being dependent on service requirement. Thus, if plain carbon

steel is to be hard without any appreciable ductility, a temperature of about 150C will be

required.

8.10 SHOT BLASTING:-

Bombarding the component with lead filings does shot blasting. The reason

for shot blasting is to clean the surface i.e. removes scales and unwanted material from

the component. This process of case hardening is used to harden the gears & shafts of the

tractor. But we know that the hardness of any substance increases, the brittleness of the

material also increases.

Major component being heat-treated in the shop:-

Bull pin shaft

Input shaft

Drive shaft

Bull gear

Bevel gear

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CHAPTER-9

9.1CONCLUSION

Working on this vocational training in HMT was truly a nice experience for me. It

proved me quiet helpful from the view point of an engineer in future. I gained a lot of

technquies on working with heavy machines i.e. how to work on it , how to handle it

successfully, how to handle the problems etc.

Truly speaking practical knowledge about machine is more important than

theoretical knowledge. At last I am very thankful to all those persons without whose

cooperation this training would be incomplete and to all my collegues.

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REFERENCE:-

www.Wikipedia.org.

www. Slideshare.com

HMT manuals

self notes

45.