This training report summarizes the author's learning from a vocational training at the Regional Workshop Mugma of Eastern Coalfields Limited. The training focused on repair activities to support continued availability of different machines throughout the company. The author thanks the managers who organized and oversaw the training. The report includes sections on the transmission section and machine shop, engine overhauling shop, and sub-assembly repair shop. It provides an overview of transmission types, engine systems, and hydraulic systems studied during the training.

1. TRAINING REPORT
THIS REPORT HIGHLIGHTS MY LEARNING OF VARIOUS REPAIR ACTIVITIES
UNDERTAKEN AT REGIONAL WORKSHOP MUGMA OF EASTERN COALFIELDS
LIMITED FOR SUPPORTING CONTINUED AVAILABILITY OF DIFFERENT MACHINES
RUNNING THROUGHOUT THE COMPANY.
2015
RUDRO BANERJEE
ASANSOLENGINEERINGCOLLEGE
1/15/2015

2. Preface
Industries are considered as backbone of a country and at the heart of industries lives
engineering. Engineering is the medium by which humans can convert thoughts into reality. It
has simplified our life. We are surrounded by it. Right from a safety pin to giant heavy earth
moving machines everything is the gift of engineering. Thus, as engineers, it is our responsibility
to take the nation forward.
A good engineer is also a keen observer. He should develop the quality to watch and learn. He
must question the practicality of every object so as to refine its working and design. For the
cultivation of these qualities merely theoretical knowledge is not sufficient. The application of
the theories is more important; hence practical knowledge is important. Only the incorporation
of theoretical knowledge together with practical experience makes an ideal engineer.
Theoretical knowledge is the foundation on which the practical knowledge is added.
Thus to acquire practical knowledge I went to “Regional Workshop, Mugma” which is under
Eastern Coalfields Limited, a subsidiary of Coal India Limited, for my vocational training. All the
data in this report are correct to my knowledge.
I would like to thank the General Manager (HRD), ECL and Mr. Naveen Kumar, G.M. ECL Mugma
Workshop, for giving me this opportunity to visit the workshop and work under the guidance of
head engineers of various departments. I would also like to thank Mr. Feroz Khan and Mr. A
Kumar, our mentors, who constantly monitored our progress during the training. Finally I would
like to specially thank Mr. C Nandi (T.P.O), Mechanical Engineering Department for arranging
this training.
Mentor G.M.,R/W Mugma G.M (HRD), ECL

3. INDEX
1 Brief history of ECL
2 Transmission section and Machine Shop
2.1 Introduction
2.2 Why do we need a transmission?
2.3 Types of transmission
2.3.1 Hydraulic Transmission System
2.3.2 Mechanical Transmission System
2.3.3 Manual Transmission
2.3.4 Automatic Transmission
2.3.5 Comparison of manual and automatic transmission
3 Engine Overhauling Shop
3.1 Introduction
3.2 List of basic parts of a 4-stroke IC engine
3.3 An overview of Reciprocating Engines
3.4 Basic functioning of 4-stroke engine
3.5 Types of engine
3.5.1 Petrol engine
3.5.2 Diesel engine
3.5.3 Comparison of engines
3.6 Engine Systems
3.7 Steps involved in engine overhauling

4. 3.8 Cummins Low HP Diesel Engine
3.9 Testing of Engines
3.10 Schematic diagram of Powertrain
4 Sub Assembly repair shop
4.1 Introduction to HEMM
4.2 Short note on Excavators
4.3 Study of Hydraulic systems

5. HISTORY :
Raniganj Coalfield, which falls under E.C.L is the birth place of coal mining in the Country. In 1774,
first mining operation in the Country was started in this Coalfield by Sumner & Heatly. In 1820, first
Coal Company M/s. Alexander & Company was established. In 1835, first Indian Enterprise i.e. M/s.
Carr & Tagore Company was formed. In 1843, the first joint stock coal Company i.e. M/s. Bengal Coal
Company was formed. Since then, underground coal mining operation had been continuing in Raniganj
Coalfields by numerous small owners. Raniganj Coalfield remained the principal producer of coal in
India in 19th Century and considerable period of the 20th Century.
NATIONALISATION AND AFTER:
In 1973, all Non-coking Coal Mines were nationalized and brought under Eastern Division of
Coal Mines Authority Limited. In 1975 Eastern Coalfields Limited, a Subsidiary of Coal India
Limited (C.I.L) was formed and inherited all the private sector coal mines of Raniganj
Coalfields.
GEOGRAPHIC LOCATION & AREA:
ECL mining leasehold area is 753.75 Sq.Kms and surface right area is 237.18 Sq.Kms. It is situated in
two States-West Bengal and Jharkhand. Raniganj Coalfield is spreading over Burdwan, Birbhum,
Bankura and Purulia Districts in West Bengal. Saherjuri Coalfield in Deoghar District of Jharkhand which
is being worked as SP Mines Area under ECL. Hura Coalfields in Godda District of Jharkhand is also
under ECL, where ECL’s largest opencast mine Rajmahal is situated. Heart of Raniganj Coalfields is
located on the north of Ajoy while Mejia and Parbelia are on south of Damodar River. In Dhanbad
District, Mugma field lies on the west of Barakar River. Formation of coal seems has occurred mainly in
two sequence at ECL- Raniganj measures & Barakar measures. Raniganj measures covers the entire
coalfield of Raniganj-Pandaveswar, Kajora, Jhanjra, Bankola, Kenda, Sonepur, Kunustoria, Satgram,
Sripur, Sodepur & Partly at Salanpur Areas. Barakar measures covers two areas Salanpur & Mugma
Areas, SP_Mines & Rajmahal Areas are mainly related to Barakar measure & Talchair series.
MINES & MANPOWER:
At present ECL has 98 no. of operating mines out of which 77 are underground mines, 21 are opencast
mines. The existing manpower in Eastern Coalfields Limited as on 01.07.2013 is 72973.
COAL RESERVE:
As on 1.4.2012, the total coal reserve in ECL command area upto 600 metre depth is 49.17 Billion tone
out of which 30.61 billion tone is in the State of West Bengal and 18.56 Billion tone is in the State of
Jharkhand. Total proved reserve in the state of West Bengal is 12.42 billion tonnes and 4.52 billion tone
is in the State of Jharkhand.

6. Transmission section and Machine Shop

7. Introduction
A machine consists of a power source and a power transmission system, which provides controlled
application of the power. Merriam-Webster defines transmission as an assembly of parts including the
speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a live
axle. Often transmission refers simply to the gearbox that uses gears and gear trains to provide speed
and torque conversions from a rotating power source to another device.
A transmission has multiple gear ratios (or simply "gears"), with the ability to switch between them as
speed varies. This switching may be done manually (by the operator), or automatically. Directional
(forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply
change the speed and torque (and sometimes direction) of motor output.
Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative
mechanisms include torque converters and power transformation (for example, diesel-electric
transmission and hydraulic drive system). Hybrid configurations also exist.
The transmission section and machine shop deals with overhauling of CLT, CLBT and TT-2221
transmissions. All of them are hydraulic transmissions.
Why do we need a transmission?
Transmissionsare usedtoincrease torque while reducingthe speedof aprime moveroutputshaft(e.g.
a motor crankshaft).Thismeansthatthe outputshaftof a gearbox rotatesat a slowerrate than the
inputshaft,andthisreductioninspeedproducesa mechanical advantage, increasingtorque.A gearbox
can be setup to dothe opposite andprovide anincrease inshaftspeedwithareductionof torque.
Some of the simplestgearboxesmerelychange the physical rotational directionof powertransmission.
Transmissionsystemshave founduse inawide varietyof different—oftenstationary—applications,such
as wind turbines. They are alsousedin agricultural, industrial, construction, mining and automotive
equipment.Inadditiontoordinarytransmissionequippedwithgears,suchequipmentmakesextensive
use of the hydrostaticdrive andelectrical adjustable-speed drives.
Types of transmission
On the basis of complexity transmissions may be classified into two categories:
1. Simple transmission
The simplest transmissions, often called gearboxes to reflect their simplicity (although complex systems
are also called gearboxes in the vernacular), provide gear reduction (or, more rarely, an increase in speed),
sometimes in conjunction with a right-angle change in direction of the shaft (typically in helicopters, see
picture). These are often used on PTO-powered agricultural equipment, since the axial PTO shaft is at
odds with the usual need for the driven shaft, which is either vertical (as with rotary mowers), or
horizontally extending from one side of the implement to another (as with manure spreaders, flail
mowers, and forage wagons). More complex equipment, such as silage choppers and snow blowers, have
drives with outputs in more than one direction.

8. The gearbox in a wind turbine converts the slow, high-torque rotation of the turbine into much faster
rotation of the electrical generator. These are much larger and more complicated than the PTO gearboxes
in farm equipment. They weigh several tons and typically contain three stages to achieve an overall gear
ratio from 40:1 to over 100:1, depending on the size of the turbine.
2. Multi-ratio Gears Transmission
Many applications require the availability of multiple gear ratios. Often, this is to ease the starting and
stopping of a mechanical system, though another important need is that of maintaining good fuel
efficiency.
On the basis of mechanism transmissions may be classified as:
1. Hydraulic transmission system
2. Mechanical transmission system
Hydraulic transmissionsystem: -
Fluid coupling: - A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power.
It has been used in automobile transmissions as an alternative to a mechanical clutch.
Construction of a Fluid Coupling: - It consists of a pump-generally known as impeller and a turbine
generally known as rotor, both enclosed suitably in a casing. They face each other with an air gap. The
impeller is suitably connected to the prime mover while the rotor has a shaft bolted to it. This shaft is
further connected to the driven machine through a suitable arrangement. Oil is filled in the fluid coupling
from the filling plug provided on its body.
Operating principle of fluid coupling: - There is no mechanical interconnection between the impeller
and the rotor and the power is transmitted by virtue of the fluid filled in the coupling. The impeller when

9. rotated by the prime mover imparts velocity and energy to the fluid, which is converted into mechanical
energy in the rotor thus rotating it. The fluid follows a closed circuit of flow from impeller to rotor
through the air gap at the outer periphery and from rotor to impeller again through the air gap at the inner
periphery. To enable the fluid to flow from impeller to rotor it is essential that there is difference in the
head between the two and thus it is essential that there is difference in R.P.M., known as slip between the
two. As the slip increases, more and more fluid can be transferred from the impeller to the rotor and more
torque is transmitted.
Torque Converter: - Torque converter is a hydraulic transmission which increases the torque of the
vehicle reducing its speed. It provides a continuous variation of ratio from low to high. The key
characteristic of a torque converter is its ability to multiply torque when there is a substantial difference
between input and output rotational speed, thus providing the equivalent of a reduction gear. Cars with an
automatic transmission have no clutch that disconnects the transmission from the engine.
Construction of a Torque Converter:-
There are four components inside the very strong housing of the torque converter:
 Pump
 Turbine
 Stator
 Transmission fluid

10. These are the parts in the figure turbine, stator and pump (left to right).
Operating principle of a Torque converter:-
The housing of the torque converter is bolted to the flywheel of the engine, so it turns at whatever speed
the engine is running at. The pump inside a torque converter is a type of centrifugal pump. As it spins,
fluid is flung to the outside. As fluid is flung to the outside, a vacuum is created that draws more fluid in
at the center. The fluid then enters the blades of the turbine, which is connected to the transmission. The
turbine causes the transmission to spin, which basically moves your car. The blades of the turbine are
curved. This means that the fluid, which enters the turbine from the outside, has to change direction
before it exits the center of the turbine. It is this directional change that causes the turbine to spin.
In order to change the direction of a moving object, you must apply a force to that object -- it doesn't
matter if the object is a car or a drop of fluid. And whatever applies the force that causes the object to turn
must also feel that force, but in the opposite direction. So as the turbine causes the fluid to change
direction, the fluid causes the turbine to spin. The fluid exits the turbine at the center, moving in a
different direction than when it entered. The fluid exits the turbine moving opposite the direction that the
pump(and engine) are turning. If the fluid were allowed to hit the pump, it would slow the engine down,
wasting power. This is why a torque converter has a stator. The stator resides in the very center of the

11. torque converter. Its job is to redirect the fluid returning from the turbine before it hits the pump again.
This dramatically increases the efficiency of the torque converter. The stator has a very aggressive blade
design that almost completely reverses the direction of the fluid. A one-way clutch (inside the stator)
connects the stator to a fixed shaft in the transmission (the direction that the clutch allows the stator to
spin is noted in the figure above). Because of this arrangement, the stator cannot spin with the fluid -- it
can spin only in the opposite direction, forcing the fluid to change direction as it hits the stator blades.
The figure (top to bottom) shows the pump, turbine and the stator, sending the fluid in their respective
direction.
Mechanical transmission system:-
In this type of transmission system, the driver has to manually select and engage the gear ratios.
Clutch: - A clutch is a mechanism which enables the rotary motion of one shaft to be transmitted at will
to second shaft, whose axis is coincident with that of first.
 Clutch is located between engine and gear box. When the clutch is engaged, the power flows from
the engine to the rear wheels through the transmission system and the vehicle moves. When the
clutch is disengaged, the power is not transmitted to the rear wheels and the vehicle stops, while
the engine is still running.
 Clutch is disengaged when
a) Starting the engine,
b) Shifting the gears,
c) Idling the engine
 Clutch is engaged only when the vehicle is to move and is kept engaged when the vehicle is
moving.

12. Function Of a Clutch:-
a) To permit engagement or disengagement of a gear when the vehicle is stationary and the engine is
running
b) To transmit the engine power to the road wheels smoothly without shock to the transmission system
while setting the wheel in motion.
c) To permit the engaging of gears when the vehicle is in motion without damaging the gear wheels.
Operating principle of a Clutch:-
The clutch principle is based on friction. When two friction surfaces are brought in contact with each
other and pressed they are united due to friction between them. If one is revolved the other will also
revolve. The friction between the two surfaces depends upon:
 Area of the surface,
 Pressure applied upon them,
 Coefficient of friction of the surface materials
Here, one surface is considered as driving member and the other as driven member.
The driving member of a clutch is the flywheel mounted on the crankshaft, the driven member is the
pressure plate mounted on the transmission shaft. Friction surfaces (clutch plates) are between the two
members (driving and driven). On the engagement of the clutch, the engine is connected to the
transmission (gear box) and the power flows from the engine to the rear wheels through the transmission
system. When the clutch is disengaged by pressing a clutch pedal, the engine is disconnected from the
transmission and consequently the power does not flow to the rear wheels while the engine is still
running.
On the basis of modus operandi transmission are classified as:-
1. Manual Transmission
2. Automatic Transmission

13. Manual transmission system:-
In this type of transmission system, the driver has to manually select and engage the gear ratios.
Stages of Manual Transmission:-
 Clutch fully pressed
The clutch is fully disengaged when the pedal is fully depressed. There will be no torque being transferred
from the engine to the transmission and wheels. Fully depressing the clutch allows the driver to change
gears or stop the vehicle.
 Clutch slips
The clutch slips in the point that varies between being fully depressed and released. The clutch slip is
used to start the vehicle from a stand still. It then allows the engine rotation to adjust to the newly selected
gear ratio gradually. It is recommended not to slip the clutch for a long time because a lot of heat is
generated resulting in energy wastage.
 Clutch fully released
The clutch is fully engaged when the pedal is fully released. All the engine torque will be transmitted to
the transmission. This results in the power being transmitted to the wheels with minimum loss.
Automatic transmission system:-
Automatic transmission system is the most advanced system in which drives mechanical efforts are
reduced very much and different speeds are obtained automatically. This system is generally also called
hydromatic transmission. It contains epicyclic gear arrangement, fluid coupling and torque converter. In
these planetary gears sets are placed in series to provide transmission. This type of transmission are used
by Skoda, Toyota, Lexus etc
Epicyclic gearing (planetry gearing):- it is a gear system consisting of one or more outer gears, or planet
gears, revolving about a central gear .By using epicyclic gear, different torque speed ratio can be
obtained. It also compact the size of gear box.

14. Stages of automatic transmission :-
 Park (P):- selecting the park mode will lock the transmission, thus restricting the vehicle from
moving.
 Reverse(R):- selecting the reverse mode puts the car into reverse gear, allowing the vehicle to
move backward.
 Neutral (N):- selecting neutral mode disconnects the transmission from the wheel.
 Low (L):- selecting the low mode will allow you to lower the speed to move on hilly and middy
areas.
 Drive (D):- selecting drive mode allows the vehicle to move and accelerate through a range of
gears.
Comparison between Manual and Automatic transmission:-
Mechanical transmission system Automatic transmission system
Vehicles with manual transmission are usually
cheaper
Vehicles with automatic transmission are costlier
than those of manual transmission.
Manual transmission has better fuel economy. This
is because manual transmission has better
mechanical and gear train efficiency.
Automatic transmission has not better fuel
economy. This is because automatic transmission
has not better mechanical and gear train efficiency
as compare to those of automatic transmission.
Manual transmission offers the driver more control
of the vehicle.
Automatic transmission does not offer the driver
more control of the vehicle as compare to that of
automatic transmission system.

15. Engine Overhauling and Testing Shop

16. Introduction
The engine acts as a powerhouse to vast majority of automobiles, trucks, HEMM etc. It provides the
required power in the form of torque and r.p.m for the movement of the vehicle.
The function of engine overhauling shop is complete overhauling of engines of different models e,g.;
ALU- 400 & Cummins engines which are used in pay loaders and dumpers. This shop consists of an
engine test bed and engine assembly area. It also consists of a high pressure pneumatic blower which is
used for engine cleaning purposes.
An overview of reciprocating engines
The reciprocating engine, basically a piston-cylinder device, has a wide range of application. The basic
components of such an engine are shown in the figure.
The piston reciprocates in the cylinder between two fixed positions called the top dead centre (TDC) and
the bottom dead centre (BDC). TDC is the position of the piston when it forms the smallest volume in the
cylinder; BDC is the position of the piston when it forms the largest volume in the cylinder. The distance
between the TDC and BDC is the largest distance which the piston can travel in one direction in the
cylinder, and it is called the stroke of the engine. The diameter of the piston is called the bore. The air or
the air-fuel mixture is drawn into the cylinder through the intake valve and the combustion products are
expelled from the cylinder through the exhaust valve. The minimum volume formed in the cylinder when
the piston is at TDC is called the clearance volume. The volume displaced by the piston as it moves
between TDC and BDC is called displaced volume. The ratio of maximum volume formed in the
cylinder to minimum (clearance) volume is called the compression ratio (rk) of the engine.

17. Reciprocating engines are classified as spark-ignition (SI) engines and compression-ignition (CI)
engines, depending on how the combustion process in the cylinder is initiated. The SI engine is also
called petrol engine and the CI engine is also called diesel engine.
List of basic parts of a 4-stroke IC engine
1. Engine block
2. Piston
3. Connecting rod
4. Valves
5. Injector or Spark plug
6. Crank shaft
7. Cam shaft
8. Push rod
9. Rocker
10. Fly wheel
11. Timing gears
12. Intake manifold
13. Exhaust manifold
14. Compressor
15. Lubrication oil pump
16. Oil sump
Basic functioning of a 4-stroke IC engine
In an IC engine, the piston executes four complete strokes within the cylinder, and the crankshaft
completes two revolutions for each thermodynamic cycles. A schematic of each stroke is given in figure.
Initially, the inlet valve opens (IVO) and fresh charge of fuel and air mixture is drawn into the cylinder.
Then both the intake and exhaust valves are closed, and the piston is at its lowest position (BDC). During
the compression stroke, the piston moves upwards, compressing the fuel-air mixture. Shortly before the

18. piston reaches its highest position (TDC), the spark plug fires and the mixture ignites (in case of petrol
engine), increasing the pressure and temperature of the system. The high pressure gas force the piston
down, which in turn forces the piston to go down, which in turn forces the crankshaft to rotate, producing
a useful work output during the expansion or power stroke. At the end of this stroke, the piston id at its
lowest position and the cylinder is filled with the combustion products. The piston moves upward again,
purging the exhaust gases into atmosphere (the exhaust stroke), and down a second time, drawing in
fresh air-fuel mixture through the intake valve (the intake stroke).
Types of Engines
Reciprocating engines are classified as spark-ignition (SI) engines and compression-ignition (CI)
engines, depending on how the combustion process in the cylinder is initiated. The SI engine is also
called petrol engine and the CI engine is also called diesel engine.
Petrol Engine
The petrol engine was developed by Nikolaus A. Otto, a German engineer, who first built a successful
four-stroke SI engine in 1876. The whole working process of the engine is illustrated below:
Process 1-2; Intake. The inlet valve is open, the piston moves to the BDC, admitting fuel-air mixture into
the cylinder at constant pressure.
Process 2-3; Compression. Both the valves are closed; the piston compresses the combustible mixture to
minimum volume.
Process 3-4; Combustion. The mixture is then ignited by means of a spark, combustion takes place, and
there is an increase in temperature and pressure.
Process 4-5; Expansion. The products of combustion do work on piston which moves towards the BDC,
and the pressure of temperature and gas decreases.
Process 5-6; Blow-down. The exhaust valve opens, and the pressure drops to the initial pressure.
Process 6-1; Exhaust. With the exhaust valve open, the piston moves inwards to expel the combustion
products from the cylinder at constant
pressure.
DIESEL CYCLE
Diesel Engine

19. Process 1-2; Intake. The inlet valve is open, the piston moves to the BDC, admitting fuel-air mixture into
the cylinder at constant pressure.
Process 2-3; Compression. The air then compressed by piston to minimum volume with all the valves
closed.
Process 3-4; Fuel injection and combustion. The fuel valve is open, fuel is sprayed into hot air, and
combustion takes place at constant pressure.
Process 4-5; Expansion. The combustion product expand, doing work on piston which moves out to the
maximum volume.
Process 5-6; Blow-down. The exhaust valve opens, and the pressure drops to the initial pressure.
Comparison of engine
The comparison of petrol and diesel engine is done on the basis of Compression ratio and Heat
rejection.
1. For the same heat rejection and compression ratio; ἠotto > ἠdiesel
2. For different compression ratio; ἠdiesel > ἠotto
Engine Systems
There are mainly four engine systems:
1. Fuel system: - This system is the system which is responsible for the movement of fuel from the
fuel tank to the engine, for the purpose of combustion. This system consists of fuel pump( PT
type or FIP type), fuel lines, injectors etc.
2. Lubrication system: - This is one of the most important systems. It is responsible for the
lubrication of various engine parts so that free movement is obtained without much heat loss due
to friction between parts. This system mainly consists of a high viscosity lubrication oil, lub-oil
pump and engine gallery.
3. Air system: - This system is also known as pneumatic system. It is responsible for the supply of
air required for the ignition purpose. It consists of an intake manifold, intake and exhaust valves,
exhaust manifold.
4. Cooling system: - This is one of the important systems. It is responsible for the cooling of the
engine. The engine may be oil cooled, water cooled or air cooled, depending on the size of the
engine. It consists of a pump(which circulates the water around the engine), radiator, a cooling
fan and an ECU( electronic control unit) which regulates the passage of water in the radiator.
Steps involved in Engine Overhauling
1. Clean the engine block with diesel or organic cleaner to remove dirt and engine oil.
2. Remove the Crank Head or Cap.
3. Remove the journal bearings from the crank case.
4. Put the engine block in anti-rust chemical.

20. After 1 day, pick up the engine block from the engine block from the anti-rust chemical.
5. Remove the dirt particles on the engine block by applying high pressurized jet air.
6. Assemble the CAM bushes.
7. Assemble the CAM shaft.
8. Assemble the CRANK shaft and fit the CAPS after placing the journal bearings in them. A torque
of 150 N should be applied on the bolts.
9. Assemble the Gudgeon pin in between the piston and the connecting rod.
10.Piston rings should be placed in their respective grooves.
11.Assemble the connecting rod to the crank shaft after putting the journal bearings.
12.Assemble the timing plate and the timing gears on one side of the engine block.
13.Assemble the fly-wheel and the fly-wheel housing on the other side of the engine block.
14.The fuel lines and the lubrication oil pump were installed.
15.Assemble the Lub-oil pump and the sump at the bottom of the engine.
Cummins low HP Diesel Engines
ISC 8.3 380 Specifications
Advertised Horsepower 380 HP 283 kW
Peak Torque 1050 LB-FT 1424 Nm
Governed Speed 2200 RPM
Clutch Engagement Torque 500 LB-FT 678 Nm
Number of Cylinders 6
Oil System Capacity 6.3 US Gallons 23.8 LITERS
System Weight 1895 LB 859 kg
Engine (Dry) 1695 LB 769 kg
After treatment System 200 LB 90 kg
Testing of Engine
The testing of engine consists of the following things:

21. 1. Measuring the Lub-oil pressure:-
Oil pressure should be between 2 to 6 kg/cm2
2. Measuring the engine low idle and high idle r.p.m:-
Low idle r.p.m: 3.5 and High idle r.p.m: 5
3. Measuring the diesel consumption of engine.
4. Check for any leakage from the engine block and oil seal.
Schematic diagram of the Powertrain
Sub Assembly repair shop

22. Introduction to hemm:-
HEMM stands for Heavy Earth Moving Machinery. Heavy equipment refers to heavy-duty vehicles,
specially designed for executing construction tasks, most frequently ones involving earthwork operations.

23. They are also known as, heavy machines, heavy trucks, construction equipment, engineering
equipment, heavy vehicles or heavy hydraulics. They usually comprise five equipment systems:
implement, traction, structure, power train, control and information.[1]
Heavy equipment functions
through the mechanical advantage of a simple machine, the ratio between input force applied and force
exerted is multiplied. Currently most equipment use hydraulic drives as a primary source of motion.
The first commercial continuous track vehicle was the Lombard Steam Log Hauler from 1901.
Tracks became extensively used for tanks during World War I, and after the war they became
commonplace for civilian machinery such as the bulldozer. The largest engineering vehicles, and
the largest mobile land machines altogether, are bucket-wheel excavators, built from the 1920s.
Heavy equipment requires specialized tires for various construction applications. While many
types of equipment have continuous tracks applicable to more severe service requirements, tires
are used where greater speed or mobility is required. An understanding of what equipment will
be used for during the life of the tires is required for proper selection. Tire selection can have a
significant impact on production and unit cost. There are three types of off-the-road tires,
transport for earthmoving machines, work for slow moving earth moving machines, and load
and carry for transporting as well as digging. Off-highway tires have six categories of service C
compactor, E earthmover, G grader, L loader, LS log-skidder and ML mining and logging.
Within these service categories are various tread types designed for use on hard-packed surface,
soft surface and rock. Tires are a large expense on any construction project; careful consideration
should be given to prevent excessive wear or damage.
The largest manufacturers based on 2011 revenue data as published by KHL Group:
1. Caterpillar Inc.
2. Komatsu
3. Volvo Construction Equipment
4. Hitachi- Hitachi, Ltd.
5. Liebherr Group
6. SANY Group Company Ltd.
7. Zoomlion
8. Terex
9. Deere & Company
10. XCMG
Short note on excavators:-
Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating
platform known as the "house". The house sits atop an undercarriage with tracks or wheels. A cable-

24. operated excavator uses winches and steel ropes to accomplish the movements. They are a natural
progression from the steam shovels and often called power shovels. All movement and functions of a
hydraulic excavator are accomplished through the use of hydraulic fluid, with hydraulic cylinders and
hydraulic motors. Due to the linear actuation of hydraulic cylinders, their mode of operation is
fundamentally different from cable-operated excavators.
Configurations of Excavator:-
Modern, hydraulic excavators come in a wide variety of sizes. The smaller ones are called mini or
compact excavators. For example, Caterpillar's smallest mini-excavator weighs 2,060 pounds (930 kg)
and has 13 hp; their largest model is the largest excavator available (a record previously held by the
Orenstein & Koppel RH400) the CAT 6090, it weighs in excess of 2,160,510 pounds (979,990 kg), has
4500 hp and has a bucket size of around 52.0 m³ depending on bucket fitted.
Engines in hydraulic excavators usually just drive hydraulic pumps; there are usually 3 pumps: the two
main pumps are for supplying oil at high pressure (up to 5000 psi) for the arms, swing motor, track
motors, and accessories, and the third is a lower pressure (700 psi) pump for Pilot Control, this circuit
used for the control of the spool valves, this allows for a reduced effort required when operating the
controls.
The two main sections of an excavator are the undercarriage and the house. The undercarriage includes
the blade (if fitted), tracks, track frame, and final drives, which have a hydraulic motor and gearing
providing the drive to the individual tracks, and the house includes the operator cab, counterweight,
engine, fuel and hydraulic oil tanks. The house attaches to the undercarriage by way of a center pin. High
pressure oil is supplied to the tracks' hydraulic motors through a hydraulic swivel at the axis of the pin,
allowing the machine to slew 360° unhindered.
The main boom attaches to the house, and can be one of several different configurations:
 Most are mono booms: these have no movement apart from straight up and down.
 Some others have a knuckle boom which can also move left and right in line with the machine.
 Another option is a hinge at the base of the boom allowing it to hydraulically pivot up to 180°
independent to the house; however, this is generally available only to compact excavators.
 There are also triple-articulated booms (TAB).
Attached to the end of the boom is the stick (or dipper arm). The stick provides the digging force needed
to pull the bucket through the ground. The stick length is optional depending whether reach (longer stick)
or break-out power (shorter stick) is required.
On the end of the stick is usually a bucket. A wide, large capacity (mud) bucket with a straight cutting
edge is used for cleanup and leveling or where the material to be dug is soft, and teeth are not required. A
general purpose (GP) bucket is generally smaller, stronger, and has hardened side cutters and teeth used to
break through hard ground and rocks. Buckets have numerous shapes and sizes for various applications.
There are also many other attachments which are available to be attached to the excavator for boring,
ripping, crushing, cutting, lifting, etc.
Before the 1990s, all excavators had a long or conventional counterweight that hung off the rear of the
machine to provide more digging force and lifting capacity. This became a nuisance when working in
confined areas. In 1993 Yanmar launched the world's first Zero Tail Swing excavator, which allows the

25. counterweight to stay inside the width of the tracks as it slews, thus being safer and more users friendly
when used in a confined space. This type of machine is now widely used throughout the world.
There are two main types of "Control" configuration generally use in excavators to control the boom and
bucket, both of which spread the four main digging controls between two x-y joysticks. This allows a
skilled operator to control all four functions simultaneously.
The excavator maneuvers with the help of track chain which is powered by the track motor. The
movement of the over carriage is done by the swing motor. Both the motors are hydraulic.
The boom movement of the excavator is controlled by the boom cylinder. The arm movement is
controlled by the stick cylinder. The bucket movement is controlled by the loader cylinder.
Study of hydraulic systems:-

26. A fundamental feature of hydraulic systems is the ability to apply force or torque multiplication in an easy
way, independent of the distance between the input and output, without the need for mechanical gears or
levers, either by altering the effective areas in two connected cylinders or the effective displacement
(cc/rev) between a pump and motor. In normal cases, hydraulic ratios are combined with a mechanical
force or torque ratio for optimum machine designs such as boom movements and track-drives for an
excavator.
Hydraulic circuits:-
For the hydraulic fluid to do work, it must flow to the actuator and/or motors, then return to a reservoir.
The fluid is then filtered and re-pumped. The path taken by hydraulic fluid is called a hydraulic circuit of
which there are severaltypes. Open center circuits use pumps which supply a continuous flow. The flow
is returned to tank through the control valve's open center; that is,when the control valve is centered,it
provides an open return path to tank and the fluid is not pumped to a high pressure. Otherwise,if the
control valve is actuated it routes fluid to and from an actuator and tank. The fluid's pressure will rise to
meet any resistance,since the pump has a constant output. If the pressure rises too high, fluid returns to
tank through a pressure relief valve. Multiple control valves may be stacked in series. This type of circuit
can use inexpensive, constant displacement pumps.
Closed center circuits supply full pressure to the control valves, whether any valves are actuated or not.
The pumps vary their flow rate,pumping very little hydraulic fluid until the operator actuates a valve. The
valve's spool therefore doesn't need an open center return path to tank. Multiple valves can be connected
in a parallel arrangement and system pressure is equal for all valves.
Components ofhydraulic system:-
Hydraulic pump:
Hydraulic pumps supply fluid to the components in the system. Pressure in the system develops in
reaction to the load. Hence, a pump rated for 5,000 psi is capable of maintaining flow against a load of
5,000 psi.
Pumps have a power density about ten times greater than an electric motor (by volume). They are
powered by an electric motor or an engine, connected through gears, belts, or a flexible elastomeric
coupling to reduce vibration.
Common types of hydraulic pumps to hydraulic machinery applications are;
1. Gear pump: cheap, durable (especially in g-rotor form), simple. Less efficient, because they are
constant (fixed) displacement, and mainly suitable for pressures below 20 MPa (3000 psi).
2. Vane pump: cheap and simple, reliable. Good for higher-flow low-pressure output.
3. Axial piston pump: many designed with a variable displacement mechanism, to vary output flow
for automatic control of pressure. There are various axial piston pump designs, including
swashplate (sometimes referred to as a valve plate pump) and check-ball (sometimes referred to
as a wobble plate pump). The most common is the swashplate pump. A variable-angle
swashplate causes the pistons to reciprocate a greater or lesser distance per rotation, allowing
output flow rate and pressure to be varied (greater displacement angle causes higher flow rate,
lower pressure, and vice versa).

27. 4. Radial piston pump: normally used for very high pressure at small flows.
Control valves:
Directional control valves route the fluid to the desired actuator. They usually consist of a spool inside a
cast iron or steel housing. The spool slides to different positions in the housing, and intersecting grooves
and channels route the fluid based on the spool's position.
The spool has a central (neutral) position maintained with springs; in this position the supply fluid is
blocked, or returned to tank. Sliding the spool to one side routes the hydraulic fluid to an actuator and
provides a return path from the actuator to tank. When the spool is moved to the opposite direction the
supply and return paths are switched. When the spool is allowed to return to neutral (center) position the
actuator fluid paths are blocked, locking it in position.
Directional control valves are usually designed to be stackable, with one valve for each hydraulic
cylinder, and one fluid input supplying all the valves in the stack.
Pressure relief valves are used in several places in hydraulic machinery; on the return circuit to
maintain a small amount of pressure for brakes, pilot lines, etc... On hydraulic cylinders, to prevent
overloading and hydraulic line/seal rupture. On the hydraulic reservoir, to maintain a small positive
pressure which excludes moisture and contamination.
Pressure regulators reduce the supply pressure of hydraulic fluids as needed for various circuits.
Sequence valves control the sequence of hydraulic circuits; to ensure that one hydraulic cylinder is
fully extended before another starts its stroke.
Check valves are one-way valves, allowing an accumulator to charge and maintain its pressure after
the machine is turned off.
Pilot controlled Check valves are one-way valve that can be opened (for both directions) by a foreign
pressure signal. For instance if the load should not be held by the check valve anymore. Often the foreign
pressure comes from the other pipe that is connected to the motor or cylinder.
Counterbalance valves are in fact a special type of pilot controlled check valve. Whereas the check
valve is open or closed, the counterbalance valve acts a bit like a pilot controlled flow control.
Cartridge valves are in fact the inner part of a check valve; they are off the shelf components with a
standardized envelope, making them easy to populate a proprietary valve block. They are available in
many configurations; on/off, proportional, pressure relief, etc. They generally screw into a valve block
and are electrically controlled to provide logic and automated functions.
Hydraulic fuses are in-line safety devices designed to automatically seal off a hydraulic line if
pressure becomes too low, or safely vent fluid if pressure becomes too high.