TRAINING REPORT

SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING

OF

LUDHIANA COLLEGE OF ENGINEERING AND TECHNOLOGY,

KATANI KALAN, LUDHIANA AS PART OF COURSE WORK OF

B.TECH. (MECHANICAL ENGINEERING)

PUNJAB TECHNICAL UNIVERSITY

KAPURTHALA

SUBMITTED BY

Harminder Singh

B- Tech., Mech. Engg.

Univ. Roll No. L-90491175389.

CONTENTS

PREFACE

The globe is shrinking. The world is taken over by the technicians. A day after day

a new technology arises. A technician without practical knowledge is zero, dont matter

how many books you have studied. Practical know how is must to be successful.

Industrial training is the bridge for a student that takes him from the world of

theoretical knowledge to that of practical one.

Training in a good industry is highly conducive for:

1. Development of solid foundation of knowledge and personality.

2. Confidence building.

3. Pursuit of excellence and discipline.

4. Enhancement of creativity through motivation and drive which helps to

produce professional and well trained for the rigorous of the job/society.

The present report has been done as an industrial training of six weeks for the

completion of 4th semester of BTech Mechanical Engineering.

During the training I got the exposure to various equipment and machines their

maintenance and technology concerning the repairing the Diesel Locomotive and hence

was assisted in developing self-confidence. The training helped me in implementing my

theoretical knowledge to the actual industrial environment.

This training at the NORTHERN RAILWAY DIESEL SHED LUDHIANA

is definitely going to play an important role in developing an aptitude for acquiring

knowledge hard work and self confidence necessary for successful future.

ACKNOLEDGEMENT

In these six weeks of industrial training, I wish to my attribute my profound

sense of gratitude without whose generous co-operation and co-ordination it would have

been highly difficult for me to have such a successful training experience in the

organization, in every game of life these are multitude of players whose are the real

heroes and this experience there are many loyal and phenomenally selfless friends, co-

workers and my bosses in industry, I am overwhelmed.

Few tasks are more enjoyable and fulfilling than acknowledging my gratitude to

all those, who have helped in this effort in so many ways. I take this opportunity to

express my sincere thanks to the management of NORTHERN RAILWAY DIESEL

SHED LUDHIANA of permitting me to observe and study the whole setup of factory.

I owe more than a debt of gratitude to Mr. R.P.Ram (Principal), Senior Section

Engineer Mr. Kuldeep Rai, and specially Thanks to Mr. Sarbjeet Singh (Mechanic) &

all the staff for their corporation & guidance made it possible to complete the work. I am

equally thankful to my faculty teacher for providing me this opportunity to work with

such a big company.

Certificate

OVERVIEW

Early internal combustion engine-powered locomotives used gasoline as their

fuel. Soon after Dr. Rudolf Diesel patented his first compression ignition engine in 1892,

its application for railway propulsion was considered. Progress was slow, however, due

to the poor power-to-weight ratio of the early engines, as well as the difficulty inherent in

mechanically applying power to multiple driving wheels on swivelling trucks (bogies).

Steady improvements in the Diesel engine's design (many developed by Sulzer

Ltd. of Switzerland, with whom Dr. Diesel was associated for a time) gradually reduced

its physical size and improved its power-to-weight ratio to a point where one could be

mounted in a locomotive. Once the concept of Diesel-electric drive was accepted the pace

of development quickened. By the mid 20th century the Diesel locomotive had become

the dominant type of locomotive in much of the world, offering greater flexibility and

performance than the steam locomotive, as well as substantially lower operating and

maintenance costs. Currently, almost all Diesel locomotives are Diesel-electric.

NORTHERN RAILWAY, DIESEL SHED, LUDHIANA

Chapter-1 INTRODUCTION

_____________________________________________________________ Diesel Shed Ludhiana came into existence on 29.09.1977. Initially, the shed was

designed to home 60 WDM2 locos. Later, it was expanded to home 100 WDM2 locos in

the year 1987-88. Further the total holding of shed was increased to 150 locos in the year

1993-94. Present loco holding of Diesel Shed, Ludhiana is 170 having different types of

locos i.e. WDM2, WDM3A & WDG3A.

Diesel Shed, Ludhiana is presently the biggest shed on the Northern Railway and

the 3rd largest on Indian Railways. The total kilometers earning is approximately 22 lakh

kilometers per month and the shed is running a mail link of 96 locos consisting of various

prestigious Mail/Express trains.

Diesel Shed, Ludhiana is also having a Diesel Training School and Hostel attached

to it. The Training School consists of 5 classrooms and various working models of

mechanical and electrical sub assemblies of WDM2 locos. The staying capacity in the

hostel is 72 and is having 38 double-bedded rooms. This training School is being mainly

utilized for training of running staff for Diesel conversion and refresher courses of FZR

& UMB division. In addition to this, this is also being utilized for imparting training to

the maintenance staff of the shed. It is also equipped with the recreation facilities &

gymnasium with high-tech exercise machines, indoor games etc.

Presently, Diesel Shed, LDH is ISO0-14001 Certified Shed, which is headed by

under the dynamic control of Sr.Divl. Mech.Engineer (Diesel), under whom the officers

DME-I, DME-II, ADME/H, ADME/R/Mech., ADME/R/Elect, ACMT & SMM/Stores

are working.

1.1 Various Sections In Diesel Shed:-

Turbo Section

Expressor Section

Compressor Section

Power Assembly Section

Cylinder Head Section

Machine Shop

Cross Head Section

Water Pump & Lube Oil Section

Radiator Section

Traction M/C

Governor Section

Gauge & Valve Section

Air Brake Section

Electrical Complaint Room

Auxillary M/C Section

Electrical Test Room

Magnaflux Section

Bogie Section

Valve Grinding Section

Contactor & Relay Room

Zyglo Testing Room

Fip Section

Tsc Balancing Section

Draftsman Room

Battery Section

Metallurgical Lab.

Spectro Section

Scrap Yard

Various Sections In Diesel Shed

To maintain various parts of locomotives, Diesel Shed, Ludhiana has different

sections for electrical and mechanical repairs & maintenance. Brief details are as under:-

1. 1.1 Turbo Supercharger Section

Turbo Supercharge is a machine, which uses exhaust of the diesel engine to

compress the intake air to improve the engine efficiency to about 1.5 times. At present, 4

types of TSCs are being overhauled in this section.

(i) ALCO Turbo Supercharger

(ii) ABB Turbo Supercharger

(iii) Napier Turbo Supercharger

(iv) Hispano Suiza Turbo Supercharger

All these TSCs are fully dismantled and overhauled in this section. The strength

of staff of this section is 7.

1.1.2 Fip & Injector Section

This section is responsible for maintaining the fuel injection pump and the

injector of diesel locomotives. The fuel injection pump is responsible for maintaining

desired pressure to inject the fuel, whereas the injector has the duty to spray the fuel in

the cylinder after atomization. Two types of FIPs are being used at present.

(i) 15mm FIP

(ii) 17mm FIP

All these subassemblies are being dismantled, overhauled and tested in this

section.

1.1.3 Expresser & Compressor Section

The expresser is used to maintain air pressure and vacuum pressure for breaking

system in the locomotive. This section is responsible for maintaining this subassembly.

Complete expressor or compressor is dismantled and overhauled in this section as per

Work Instructions issued to the section. The staff strength of the section is about 30.

1.1.4 Power Assembly Section

The piston and connecting rod assembly is called as power assembly. 16 power

assemblies are being used in one locomotive. Two types of pistons are being used in the

locomotive. Steel cap pistons are being used in fuel efficient locomotives, whereas

aluminium pistons are being used in conventional locomotives. The shed has switched

over to barrel shape piston rings to provide better fuel efficiency. The pistons and

connecting rods are dismantled, cleaned, zyglo tested and again are made ready for

service in this section. The staff strength of section is about 10.

1.1.5. Cylinder Head Section

This section is responsible for maintenance and overhauling of cylinder heads

of diesel locomotives. 16 Nos. cylinder heads are there in one locomotive. Each cylinder

head has four valves, two exhaust and two inlet valves. In fuel-efficient locomotives, the

valve angle is 300, whereas in conventional locomotives it is 450. The head is completely

dismantled and after cleaning and mating the valve & valve seat and overhauling the

complete components, the head is made ready for service in this section after various

tests. The staff strength of this section is about 7.

1.1.6. Cross Head Section

Crosshead is a subassembly, which is operated by camshaft to operate the valve

lever mechanism of the cylinder heads. There are 16 cross heads in one locomotive. The

cross heads operate the valve levers through two bush rods, one for exhaust and other for

air inlet. Cross heads are completely dismantled and overhauled and also the valve lever

mechanism is completely dismantled and overhauled in this section. The staff strength of

this section is about 4.

1.1.7. Pump Section

The pump section is responsible for overhauling water pump and lube oil pump

of the locomotive. Both the pumps are gear driven through crankshaft split gear train.

Every loco is having one water pump and one no. lubricating oil pump. Both the pumps

are cleaned, overhauled and made ready for service in this section. The staff strength of

this section is 4.

1.1.8. Miscelleneous Sub-assembly & Heat Exchanger Section This section is responsible for maintaining rear truck traction motor blower

which is belt driven, front truck traction motor blower which is gear driven, universal

shaft, which is used to drive radiator fan, eddy current clutch gear box used to provide

drive to radiator fan, over speed trip assembly is responsible for preventing the engine

from over-speeding. In addition to above, various heat exchangers, such as radiator, turbo

aftercooler, compressor after cooler and engine lube oil cooler are cleaned, tested &

overhauled in this section. The self-centrifuging unit of locomotive is also overhauled in

this section.

1.1.9.Bogie Section

This section is responsible for complete overhauling of undergear of the

locomotive. A locomotive is driven on line through 06 No. traction motors, which are

supplied from a generator driven by the diesel engine. These motors are fitted on 6 Nos.

axles and connected to axles through a bull gear pinion arrangement. The motors are

suspended through suspension bearing which is plain bearing in some locomotives,

whereas these are roller bearings in about 50% of locomotives. Two bogie frames are

used to house six axles and wheels and called as front bogie and rear bogie. The braking

arrangement for the locomotives is given through 8 brake cylinders, 4 on each bogie and

various brake riggings, brake shoes and brake blocks. The load of locomotive is shared

by each bogie. Each bogie has two nos. side bearers and one no. central pivot. The load

sharing between the central pivot and the side bearer is in the ratio of 60:40. The chassis

of the locomotive is having 2 Nos. central buffer couplers on each side for connection to

the train. The chassis is also having mounted 4 Nos. buffers, 2 on each side to bear

various pumps during operation. Staff strength in this section is about 70.

1.1.10. Yearly Section

Yearly section is used for complete overhauling of locomotive, engine block

and removal of various mechanical subassemblies. The yearly section carries out 24

monthly and 48 monthly schedules of the locomotives in which engine and various

subassemblies are overhauled completely. Staff strength of this section is about 90.

1.1.11. Air Brake Section

Air brake section is responsible for overhauling of brake valves of air brake

system and other safety items such as wipers, sanders, horns etc. In addition to it, various

gauges are also being maintained by this section. Staff strength of this section is about 50.

1.1.12. Valve Section

This section is responsible for maintaining fuel regulating valve, fuel relief valve,

lube oil regulating valve, lube oil relief valve, lube oil bypass valve of the locomotive.

The valves are overhauled and are set at a required pressure as per Maintenance

Instructions. Staff strength of this section is 2.

1.1.13. Speedometer Section

The speedometer section is responsible for maintaining speedometers of the

locomotive, which are responsible for recording and indicating the speed of the

locomotive. Staff strength of this section is about 16.

1.1.14. Governor Section

Governor section is responsible for maintenance of governor of the locomotive.

The governor of the locomotive is responsible for maintaining constant speed of the

engine as per requirement at every notch. At present, the shed has 3 types of governors.

(i) Woodward governor

(ii) GE or electro hydraulic governor

(iii) Microprocessor based governor

1.2 Minor Repairs Sections

1.2.1 Mail Section

Mail Section is having 2 sections i.e. Mail/Mech. and Mail Elect. section. Mail

section is responsible for maintenance of diesel engine, various mechanical

subassemblies, undergears etc. for trip schedule, monthly schedule and quarterly schedule

for mail and passenger locomotives.

1.2.2 Goods Section

Goods section is also having goods mech. and goods electrical. Goods section is

responsible for maintenance of diesel engine, various mechanical subassemblies,

undergears etc. for trip schedule, monthly schedule and quarterly schedule for goods

locomotives.

1.2.3 Quarterly & Half Yearly Section

Quarterly and half yearly section is responsible for 8 monthly, 12 monthly and 16

monthly schedules of diesel locomotives.

1.2.4 Out-Of-Course Section

OOC section is responsible for attending various major repairs of the locomotives,

which cannot be covered during minor schedule.

1.2.5 M & P Of The Shed

The shed, in its bogie section, is having two 40tonne cranes and one 10 tonne

crane. These cranes are used to lift bogies, engine blocks and various major

subassemblies. Heavy Repair Bay subassembly sections are having two cranes, 0ne

10tonne and the other is 3tonne crane. These are used for handling various

subassemblies. Every minor repair bay i.e. goods, mail, quarterly half yearly sections are

also having 3 tonne self operated cranes which are used to lift various subassemblies of

the locomotive. The shed is also having 3 Nos. fork lifters for material handling.

1.2.6 SCHEMATIC DIAGRAM OF DIESEL ELECTRIC LOCOMOTIVE

Fig. 1 schematic diagram of diesel electric locomotive

1.2.7BLOCK DIAGRAM OF DIESEL LOCOMOTIVE

RADIATOR AFTER FRAME

BOG

GI

E

EXPRESSOR OR

COMPRESSOR ROOM

ENGINE ROOM

GENERATOR ROOM

DRIVER CABIN

NOTCH COMPART

MENT

BOG

GI

E

Fig. 2 Block diagram of diesel locomotive

A Diesel locomotive is a type of railroad locomotive in which the prime mover is a

Diesel engine

1.2.8 SALIENT FEATURESSanctioned staff strength = 1331Staff on roll = 1206Total covered area = 12,577 sq. meters. Berthing capacity = 32 locos. %age of staff housed = 21%.Fuel storage capacity = 730 kiloliters. Average off take of diesel oil per day = 0.3 lakh liters (approx). Lube oil storage capacity = 350 kiloliters. Average off-take of lube oil per day = 2700 liters (approx).Annual budget of shed = Rs.___________ (approx). Average kms earned/month = 21.61 lakh kilometers.Stock items in the stores depot. = 1969 Present mail link = 96Present loco holding = 170

(a) WDM2 = 62(b) WDG3A = 44(c) WDM3A = 64

Total = 170Direct maintenance staff per loco = 4.30SFC Mail (Lts/1000GTKM) (2008-09) = 3.72

SFC Goods (Lts/1000GTKM) (2008-09) = 2.03

ACTIVITIES IN SHED SCHEDULES GIVEN BY SHOPSSchedules Periodicity Schedules Periodicity

Trip 15/20 days. IOH/M48 (By CB Shop) 4 yearsT2 30 days. POH/M96(By CB Shop) 8 years. M2 60 days. RB (By DMW/PTA) 16-22 years M4 120 days.

M12 12 months. NO.OF SCHEDULES UNDERTAKEN IN A MONTH

M24 24 months. Type of Sch No. of Sch.M48 48 months. Trip 280

M72 72 months T2 82M2 40M4/8/16/20 27M12 08M24/48 04

1.2.9 Engine Description

Diesel Engine

Main Alternator

Auxiliary Alternator

Motor Blower

Air Intakes

Rectifiers / inverters

Electric Controls

Control Stands

Batteries

Cab

Traction Motor

Pinion Gear

Fuel Tank

Air compressor

Drive Shaft

Gear Box

Radiator and Radiator Fan

Turbo charging

Sand Box

Truck Frame

Wheel

Brakes

Mechanical Transmission

Fluid Coupling

Final Drive

Hydraulic Transmission

Wheel Slip

Chapter-2 Diesel Engine

_____________________________________________________________

The diesel engine was first patented by Dr Rudolf Diesel (1858-1913) in

Germany in 1892 and he actually got a successful engine working by 1897. By 1913,

when he died, his engine was in use on locomotives and he had set up a facility with

Sulzer in Switzerland to manufacture them. His death was mysterious in that he simply

disappeared from a ship taking him to London.

The diesel engine is a compression-ignition engine, as opposed to the petrol (or

gasoline) engine, which is a spark-ignition engine. The spark ignition engine uses an

electrical spark from a "spark plug" to ignite the fuel in the engine's cylinders, whereas

the fuel in the diesel engine's cylinders is ignited by the heat caused by air being suddenly

compressed in the cylinder. At this stage, the air gets compressed into an area 1/25th of

its original volume. This would be expressed as a compression ratio of 25 to 1. A

compression ratio of 16 to 1 will give an air pressure of 500 lbs/in (35.5 bar) and will

increase the air temperature to over 800 F (427 C).

The advantage of the diesel engine over the petrol engine is that it has a higher thermal

capacity (it gets more work out of the fuel), the fuel is cheaper because it is less refined

than petrol and it can do heavy work under extended periods of overload. It can however,

in a high speed form, be sensitive to maintenance and noisy, which is why it is still not

popular for passenger automobiles.

2.1 Diesel engine: Mode of Operation

1. Suction stroke: Pure air gets sucked in by the piston sliding downward.

2.Compression stroke: The piston compresses the air above and uses thereby work,

performed by the crankshaft.

3.Power stroke: In the upper dead-center, the air is max. Compressed: Pressure and

Temperature are very high. Now the black injection pump injects heavy fuel in the hot

air. By the high temperature the fuel gets ignited immediately (auto ignition). The piston

gets pressed downward and performs work to the crankshaft.

4.Expulsion stroke: The burned exhaust gases are ejected out of the cylinder through a

second valve by the piston sliding upward again.

Fig. 3 4 stroke compression ignition (diesel) engine cycle

2.2 Diesel-electric control

A Diesel-electric locomotive's power output is independent to road speed, as long as

the units generator current and voltage limits are not exceeded. Therefore, the unit's

ability to develop tractive effort (also referred to as drawbar pull or tractive force, which

is what actually propels the train) will tend to inversely vary with speed within these

limits.

The diesel engine ideally should operate with maximum fuel economy as long as

maximum power is not required. Maintaining acceptable operating parameters was one of

the principal design considerations that had to be solved in early Diesel-electric

locomotive development, and ultimately led to the complex control systems in place on

modern units where all these parameters are solved and regulated by computer modules.

The prime mover's power output is primarily determined by its rotational speed

(RPM) and fuel rate, which are regulated by a governor or similar mechanism. The

governor is designed to react to both the throttle setting, as determined by the engineer

(driver), and the speed at which the prime mover is running.

Locomotive power output, and thus speed, is typically controlled by the engineer (driver)

using a stepped or "notched" throttle that produces binary-like electrical signals

corresponding to throttle position. This basic design lends itself well to multiple unit

(MU) operation by producing discrete conditions that assure that all units in a consist

respond in the same way to throttle position. Binary encoding also helps to minimize the

number of train lines (electrical connections) that are required to pass signals from unit to

unit. For example, only four train lines are required to encode all throttle positions.

In older locomotives, the throttle mechanism was ratcheted so that it was not

possible to advance more than one power position at a time. The engineer could not, for

example, pull the throttle from notch 2 to notch 4 without stopping at notch 3. This

feature was intended to prevent rough train handling due to abrupt power increases

caused by rapid throttle motion ("throttle stripping," an operating rules violation on many

railroads). Modern locomotives no longer have this restriction, as their control systems

are able to smoothly modulate power and avoid sudden changes in train loading

regardless of how the engineer (driver) operates the controls.

2.3 WORKING OF DIESEL LOCOMOTIVE When the throttle is in the idle position, the prime mover will be receiving minimal

fuel, causing it to idle at low RPM. Also, the traction motors will not be connected to the

main generator and the generator's field windings will not be excited (energized)the

generator will not produce electricity with no excitation. Therefore, the locomotive will

be in "neutral." Conceptually, this is the same as placing an automobile's transmission

into neutral while the engine is running.

To set the locomotive in motion, the reverser control handle is placed into the correct

position (forward or reverse), the brake is released and the throttle is moved to the run 1

position (the first power notch). An experienced engineer (driver) can accomplish these

steps in a coordinated fashion that will result in a nearly imperceptible start. The

positioning of the reverser and movement of the throttle together is conceptually like

shifting an automobile's automatic transmission into gear while the engine is idling

Placing the throttle into the first power position will cause the traction motors to be

connected to the main generator and the latter's field coils to be excited. It will not,

however, increase prime mover RPM. With excitation applied, the main generator will

deliver electricity to the traction motors, resulting in motion. If the locomotive is running

"light" (that is, not coupled to a train) and is not on an ascending grade it will easily

accelerate. On the other hand, if a long train is being started, the locomotive may stall as

soon as some of the slack has been taken up, as the drag imposed by the train will exceed

the tractive force being developed. An experienced engineer (driver) will be able to

recognize an incipient stall and will gradually advance the throttle as required to maintain

the pace of acceleration.

As the throttle is moved to higher power notches, the fuel rate to the prime mover will

increase, resulting in a corresponding increase in RPM and horsepower output. At the

same time, main generator field excitation will be proportionally increased to absorb the

higher power. This will translate into increased electrical output to the traction motors,

with a corresponding increase in tractive force. Eventually, depending on the

requirements of the train's schedule, the engineer (driver) will have moved the throttle to

the position of maximum power and will maintain it there until the train has accelerated

to the desired speed.

As will be seen in the following discussion, the propulsion system is designed to produce

maximum traction motor torque at start-up, which explains why modern locomotives are

capable of starting trains weighing in excess of 15,000 tons, even on ascending grades.

Current technology allows a locomotive to develop as much as 30 percent of its loaded

driver weight in tractive force, amounting to some 120,000 pounds of drawbar pull for a

large, six-axle freight (goods) unit. In fact, a consist of such units can produce more than

enough drawbar pull at start-up to damage or derail cars (if on a curve), or break couplers

(the latter being referred to in North American railroad slang as "jerking a lung").

Therefore, it is incumbent upon the engineer (driver) to carefully monitor the amount of

power being applied at start-up to avoid damage. In particular, "jerking a lung" could be a

calamitous matter if it were to occur on an ascending grade.

As previously explained, the locomotive's control system is designed so that the

main generator electrical power output is matched to any given engine speed. Due to the

innate characteristics of traction motors, as well as the way in which the motors are

connected to the main generator, the generator will produce high current and low voltage

at low locomotive speeds, gradually changing to low current and high voltage as the

locomotive accelerates. Therefore the net power produced by the locomotive will remain

constant for any given throttle setting.

In older designs, the prime mover's governor and a companion device, the load

regulator, play a central role in the control system. The governor has two external inputs:

requested engine speed, determined by the engineer's throttle setting, and actual engine

speed (feedback). The governor has two external control outputs: fuel injector setting,

which determines the engine fuel rate, and load regulator position, which affects main

generator excitation. The governor also incorporates a separate over speed protective

mechanism that will immediately cut off the fuel supply to the injectors and sound an

alarm in the cab in the event the prime mover exceeds a defined RPM. It should be noted

that not all of these inputs and outputs are necessarily electrical.

The load regulator is essentially a large potentiometer that controls the main

generator power output by varying its field excitation and hence the degree of loading

applied to the engine. The load regulator's job is relatively complex, because although the

prime mover's power output is proportional to RPM and fuel rate, the main generator's

output is not (which characteristic was not correctly handled by the Ward Leonard

elevator drive system that was initially tried in early locomotives).

As the load on the engine changes, its rotational speed will also change. This is detected

by the governor via a change in the engine speed feedback signal. The net effect is to

adjust both the fuel rate and the load regulator position. Therefore, engine RPM and

torque will remain constant for any given throttle setting, regardless of actual road speed.

In newer designs controlled by a traction computer, each engine speed step is

allotted an appropriate power output, or kW reference, in software. The computer

compares this value with actual main generator power output, or kW feedback,

calculated from traction motor current and main generator voltage feedback values. The

computer adjusts the feedback value to match the reference value by controlling the

excitation of the main generator, as described above. The governor still has control of

engine speed, but the load regulator no longer plays a central role in this type of control

system. However, the load regulator is retained as a back-up in case of engine

overload. Modern locomotives fitted with electronic fuel injection (EFI) may have no

mechanical governor, however a virtual load regulator and governor are retained with

computer modules.

Fig.4 3200Hp Diesel Locomotive Engine

Traction motor performance is controlled either by varying the DC voltage output of

the main generator, for DC motors, or by varying the frequency and voltage output of the

VVVF for AC motors. With DC motors, various connection combinations are utilized to

adapt the drive to varying operating conditions.

Fig. 5 Top View of Diesel Locomotive Engine

Here are some of the specifications of this engine:

Number of cylinders: 12

Compression ratio: 16:1

Displacement per cylinder: 11.6 L (710 in3)

Cylinder bore: 230 mm (9.2 inches)

Cylinder stroke: 279 mm (11.1 inches)

Full speed: 904 rpm

Normal idle speed: 269 rpm

At standstill, main generator output is initially low voltage/high current, often in

excess of 1000 amperes per motor at full power. When the locomotive is at or near

standstill, current flow will be limited only by the DC resistance of the motor windings

and interconnecting circuitry, as well as the capacity of the main generator itself. Torque

in a series-wound motor is approximately proportional to the square of the current.

Hence, the traction motors will produce their highest torque, causing the locomotive to

develop maximum tractive effort, enabling it to overcome the inertia of the train. This

effect is analogous to what happens in an automobile automatic transmission at start-up,

where it is in first gear and thus producing maximum torque multiplication.

As the locomotive accelerates, the now-rotating motor armatures will start to

generate a counter-electromotive force (back EMF, meaning the motors are also trying to

act as generators), which will oppose the output of the main generator and cause traction

motor current to decrease. Main generator voltage will correspondingly increase in an

attempt to maintain motor power, but will eventually reach a plateau. At this point, the

locomotive will essentially cease to accelerate, unless on a downgrade. Since this plateau

will usually be reached at a speed substantially less than the maximum that may be

desired, something must be done to change the drive characteristics to allow continued

acceleration. This change is referred to as "transition," a process that is analogous to

shifting gears in an automobile.

2.4 Starting:

A diesel engine is started (like an automobile) by turning over the crankshaft

until the cylinders "fire" or begin combustion. The starting can be done electrically or

pneumatically. Pneumatic starting was used for some engines. Compressed air was

pumped into the cylinders of the engine until it gained sufficient speed to allow ignition,

then fuel was applied to fire the engine. The compressed air was supplied by a small

auxiliary engine or by high pressure air cylinders carried by the locomotive.

Electric starting is now standard. It works the same way as for an automobile,

with batteries providing the power to turn a starter motor which turns over the main

engine. In older locomotives fitted with DC generators instead of AC alternators, the

generator was used as a starter motor by applying battery power to it.

2.5 Transition methods include:

Series / Parallel or "motor transition."

o Initially, pairs of motors are connected in series across the main generator. At higher speed, motors are re-connected in parallel across the main

generator.

Field shunting," "field diverting" or "weak fielding."

o Resistance is connected in parallel with the motor field. This has the effect of increasing the armature current, producing a corresponding increase in

motor torque and speed.

Note: Both methods may also be combined, to increase the operating speed range.

Generator transition

o Reconnecting the two separate internal main generator stator windings from parallel to series to increase the output voltage.

In older locomotives, it was necessary for the engineer to manually execute

transition by use of a separate control. As an aid to performing transition at the right time,

the load meter (an indicator that informs the engineer on how much current is being

drawn by the traction motors) was calibrated to indicate at which points forward or

backward transition should take place. Automatic transition was subsequently developed

to produce better operating efficiency, and to protect the main generator and traction

motors from overloading due to improper transition.

The hybrid diesel locomotive is an incredible display of power and ingenuity. It

combines some great mechanical technology, including a huge, 12-cylinder, two-stroke

diesel engine, with some heavy duty electric motors and generators, throwing in a little

bit of computer technology for good measure.

This combination of diesel engine and electric generators and motors makes the

locomotive a hybrid vehicle. In this article, we'll start by learning why locomotives are

built this way and why they have steel wheels. Then we'll take a look at the layout and

key components.

2.6 Size Does Count

Basically, the more power you need, the bigger the engine has to be. Early

diesel engines were less than 100 horse power (hp) but today the US is building 6000 hp

locomotives. For a UK locomotive of 3,300 hp (Class 58), each cylinder will produce

about 200 hp, and a modern engine can double this if the engine is turbocharged.

The maximum rotational speed of the engine when producing full power will be

about 1000 rpm (revolutions per minute) and the engine will idle at about 400 rpm.

These relatively low speeds mean that the engine design is heavy, as opposed to a high

speed, lightweight engine. However, the UK HST (High Speed Train, developed in the

1970s) engine has a speed of 1,500 rpm and this is regarded as high speed in the railway

diesel engine category. The slow, heavy engine used in railway locomotives will give

low maintenance requirements and an extended life.

There is a limit to the size of the engine which can be accommodated within the

railway loading gauge, so the power of a single locomotive is limited. Where additional

power is required, it has become usual to add locomotives. In the US, where freight

trains run into tens of thousands of tons weight, four locomotives at the head of a train are

common and several additional ones in the middle or at the end are not unusual.

2.7 Important Maintenance Instruction For Cylinder Head.

Study the condition of cylinder head combustion chamber face, cooling jackets

and its valves thoroughly before its dismantling.

Clean cylinder head thoroughly especially cooling jackets.

Do RDF of cylinder head combustion face, defect any cracks.

Check cylinder head hydraulically at 5kg/sq. cm and 8. Temp of water up to a min

of 15 minutes.

Check the diameter of valve guide after removing its carbon deposits.

Check the clean nozzle, cooling sleeves seat of cylinder head.

Use liquid nitrogen for valve seat insert fitting.

Check valve seat inserts for cracks by RDF (After grinding).

Before final assembly check all valve seat inserts as well as of nozzle cooling

sleeve.

Compare seat should be lapped thoroughly and it should be 1/16 thick all over.

2.8 Cylinder Head

Fig. 6 Cylinder Head

2.9 To V or not to V

Diesel engines can be designed with the cylinders "in-line", "double banked" or in

a "V". The double banked engine has two rows of cylinders in line. Most diesel

locomotives now have V form engines. This means that the cylinders are split into two

sets, with half forming one side of the V. A V8 engine has 4 cylinders set at an angle

forming one side of the V with the other set of four forming the other side. The

crankshaft, providing the drive, is at the base of the V. The V12 was a popular design

used in the UK. In the US, V16 is usual for freight locomotives and there are some

designs with V20 engines.

2.10 Tractive Effort, Pull and Power

Before going too much further, we need to understand the definitions of tractive

effort, drawbar pull and power. The definition of tractive effort (TE) is simply the force

exerted at the wheel rim of the locomotive and is usually expressed in pounds (lbs) or

kilo Newtons (KN). By the time the tractive effort is transmitted to the coupling between

the locomotive and the train, the drawbar pull, as it is called will have reduced because of

the friction of the mechanical parts of the drive and some wind resistance.

Power is expressed as horsepower (hp) or kilo Watts (kW) and is actually a rate of

doing work. A unit of horsepower is defined as the work involved by a horse lifting

33,000 lbs one foot in one minute. In the metric system it is calculated as the power

(Watts) needed when one Newton of force is moved one metre in one second. The

formula is P = (F*d)/t where P is power, F is force, d is distance and t is time. One

horsepower equals 746 Watts.

The relationship between power and drawbar pull is that a low speed and a high

drawbar pull can produce the same power as high speed and low drawbar pull. If you

need to increase higher tractive effort and high speed, you need to increase the power. To

get the variations needed by a locomotive to operate on the railway, you need to have a

suitable means of transmission between the diesel engine and the wheels.

One thing worth remembering is that the power produced by the diesel engine is

not all available for traction. In a 2,580 hp diesel electric locomotive, some 450 hp is lost

to on-board equipment like blowers, radiator fans, air compressors and "hotel power" for

the train.

Chapter-3 WDM-2 Diesel Locomotive

_____________________________________________________________

The first few prototype WDM-2s were imported. After Diesel Locomotive Works

(DLW) completed construction of its factory in Varanasi, production of the locomotives

began in India. The first 12 locos were built using kits imported from ALCO in the

United States. After that DLW started manufacturing the WDM-2 locomotives from their

own components. Since then over 2,800 locomotives have been manufactured and the

WDM-2 has become the most popular locomotive in India.

However, even before the arrival of WDM-2 another type of diesel locomotive

was imported from ALCO beginning in 1957. This locomotive was classified as WDM-1.

Later a number of modifications were made and a few subclasses were created.

This includes WDM-2A, WDM-2B and WDM-3A (formerly WDM-2C).

The WDM-2 is the diesel workhorse of the Indian Railways, being very reliable

and rugged.

The class WDM-2 is Indian Railways' workhorse diesel locomotive. The first

units were imported fully built from the American Locomotive Company (Alco) in 1962.

Since 1964, it has been manufactured in India by the Diesel Locomotive Works (DLW),

Varanasi. The model name stands for broad gauge (W), diesel (D), mixed traffic (M)

engine. The WDM-2 is the most common diesel locomotive of Indian Railways.

The WDM-2A is a variant of the original WDM-2. These units have been retro-

fitted with air brakes, in addition to the original vacuum brakes. The WDM-2B is a more

recent locomotive, built with air brakes as original equipment. The WDM-2 locos have a

maximum speed of 120 km/h (75 mph), restricted to 100 km/h (62 mph) when run long

hood forward. The gear ratio is 65:18.

Types of Diesel locomotives

WDM2 BG Main Line Locomotive 2600HP

WDM3 BG Main Line Locomotive 3100HP

WDM6 BG Main Line Locomotive 1350HP

WDM7 BG Main Line Locomotive 2150HP

WDG4BG Main Line Goods Locomotive 4000HP

WDP4 BG Main Line Passenger Locomotive 4000HP

WDS6 BG Shunting Locomotive 1350HP

WDP1 BG Inter City Express Locomotive 2300HP

WDP2 BG High HP Passenger Locomotive 3100HP

WDG3A BG High Goods Locomotive 3100HP

WDG3C BG High HP Goods Locomotive 3300HP

YDM4 MG Main Line Locomotive 1350HP

3.1 Technical specifications

Builders Alco, DLW

Engine

Alco 251-B, 16 cylinder, 2,600 hp (2,430 hp site rating) with Alco

710/720/?? Turbo supercharged engine. 1,000 rpm max, 400 rpm idle;

228 mm x 266 mm bore/stroke; compression ratio 12.5:1. Direct fuel

injection, centrifugal pump cooling system (2,457 l/min at 1,000 rpm), fan

driven by eddy current clutch (86 hp at 1,000 rpm).Governor GE 17MG8 / Woodwards 8574-650.

TransmissionElectric, with BHEL TG 10931 AZ generator (1,000 rpm, 770 V, 4,520

amps).

Traction motorsGE752 (original Alco models) (405 hp), BHEL 4906 BZ (AZ?) (435 hp)

and (newer) 4907 AZ (with roller bearings)Axle load 18.8 tones, total weight 112.8 t.Bogies Alco design cast frame trimount (Co-Co) bogies

Starting TE30.4 t, at adhesion 27%.

Length over

buffer beams15,862 mm.

Distance

between bogies10,516 mm.

The above requirement, in the year 1987, led to the creation of test beds at Engine

Development Directorate of RDSO at Lucknow having state of the art facilities for

developmental testing of all the variants of diesel engines being used by Indian Railways.

It included the computer based test facility for both data logging and control of engines.

The above facilities comparable to the best facilities in the world were created to

meet the following objectives:

Development of technology for improving existing Rail Traction Diesel Engines for

1. Better Fuel Efficiency

2. Higher Reliability

3. Increased Availability

Development of technology for increasing power output of existing Diesel Engines.

Develop capability for designing new Rail Traction Diesel Engines for meeting future needs of Indian Railways.

To provide effective R&D backup to Railways and Production units to

1. Maintain Quality

2. Facilitate Indigenization

3.2 Broad Gauge Main Line Freight Locomotive WDG 3A

3.2.1 Technical Information Diesel Electric main line, heavy duty goods service locomotive, with 16 cylinder ALCO

engine and AC/DC traction with micro processor controls.

Wheel Arrangement Co-CoTrack Gauge 1676 mmWeight 123 tLength over Buffers 19132 mmWheel Diameter 1092 mmGear Ratio 18 : 74Min radius of Curvature 117 m

Maximum Speed 105 Kmph

Diesel Engine Type : 251 B,16 Cyl.- V

HP 3100 Brake IRAB-1Loco Air, DynamicTrain AirFuel Tank Capacity 6000 litres

3.3 Broad Gauge Main Line Mixed Service LOCO WDM 3D

3.3.1 Technical Information Diesel Electric Locomotive with micro processor control suitable for main line

mixed Service train operation.

Wheel

Arrangement

Co-Co

Track Gauge 1676 mmWeight 117 tMax. Axle Load 19.5 tLength over

Buffer

18650 mm

Wheel Diameter 1092 mmGear Ratio 18 : 65Maximum

Speed

120 Kmph

Diesel Engine Type: 251 B-16 Cyl. V type HP 3300 HP (standard UIC condition)Transmission Electric AC / DCBrake IRAB-1 systemLoco Air, Dynamic, HandTrain AirFuel Tank

Capacity

5000 litres

3.4 Broad Gauge Shunting Locomotive WDS 6AD

3.4.1Technical Information

A heavy duty shunting Diesel Electric Locomotive for main line and branch line

train operation. This locomotive is very popular with Steel Plants and Port Trusts.

Wheel Arrangement Co-Co

Track Gauge 1676 mmWeight 113 tLength over Buffer 17370 mm

Wheel Diameter 1092 mmGear Ratio 74 : 18Maximum Speed 50 KmphDiesel Engine Type : 251 D-6 Cyl. in-lineHP 1350 / 1120 HP (std.)Transmission Electric AC / DCBrake IRAB-1Loco AirTrain Air

Fuel Tank Capacity 5000 litres

3.5 Engine Test Bed Facilities

The test bed facilities in RDSO are equipped with four Test Cells. These Test Cells

house four (16 cylinders GMEMD, 16 cylinders ALCO, 12 cylinders ALCO, 6 cylinders

ALCO) types of DLW manufactured Engines. Each test cell has its own microprocessor

controlled data acquisition and control systems and Video Display Unit (VDU) for

pressure, temperature and other parameters. Various transducers relay the information

from the test engines to the microprocessor based test commander for further processing

with the help of sophisticated software. Each test cell has an instrumentation catering to

60 to 120 pressures / temperature transducers along with sophisticated equipments like

gravimetric fuel balance for measurement of fuel consumption and the equipment for

measurement of air flow.

Fig. 8 Test Bed 3.6 Fuel Consumption on 8th Notch

Since the fuel consumption at 8th notch is highest and also since Locomotives run at this notch for longer duration as compared to other notches, fuel consumption at this

notch is one of the important fuel efficiency index. This is measured in terms of gm / bhp

- hr.

3.7 Fuel Consumption Over Duty Cycle

An Engine runs in the field at different notch as per requirement of speed / load of

the locomotive. The notch wise percentage running of locomotive over duty cycle for

passenger and freight operations of Indian Railways locomotives is as under:

3.8 Speed at different Notch position

Notch Speed (RPM)1 4002 4503 5504 6505 7506 8507 9158 1000

3.9 Driving a Locomotive

You don't just hop in the cab, turn the key and drive away in a diesel locomotive.

Starting a train is a little more complicated than starting your car.

The engineer climbs an 8-foot (2.4-m) ladder and enters a corridor behind the cab. He or

she engages a knife switch (like the ones in old Frankenstein movies) that connects the

batteries to the starter circuit. Then the engineer flips about a hundred switches on a

circuit-breaker panel, providing power to everything from the lights to the fuel pump.

Next, the engineer walks down a corridor into the engine room. He turns and holds

a switch there, which primes the fuel system, making sure that all of the air is out of the

system. He then turns the switch the other way and the starter motor engages. The engine

cranks over and starts running.

Next, he goes up to the cab to monitor the gauges and set the brakes once the

compressor has pressurized the brake system. He can then head to the back of the train to

release the hand brake.

Finally he can head back up to the cab and take over control from there. Once he

has permission from the conductor of the train to move, he engages the bell, which rings

continuously, and sounds the air horns twice (indicating forward motion).

The throttle control has eight positions, plus an idle position. Each of the throttle

positions is called a "notch." Notch 1 is the slowest speed, and notch 8 is the highest

speed. To get the train moving, the engineer releases the brakes and puts the throttle into

notch 1.

In this General Motors EMD 710 series engine, putting the throttle into notch 1

engages a set of contactors (giant electrical relays). These contactors hook the main

generator to the traction motors. Each notch engages a different combination of

contactors, producing a different voltage. Some combinations of contactors put certain

parts of the generator winding into a series configuration that results in a higher voltage.

Others put certain parts in parallel, resulting in a lower voltage. The traction motors

produce more power at higher voltages.

As the contactors engage, the computerized engine controls adjust the fuel injectors

to start producing more engine power.

Chapter-4 Main Parts Of An Engine

_____________________________________________________________

4.1 Main Alternator

The diesel engine drives the main alternator which provides the power to move the

train. The alternator generates AC electricity which is used to provide power for the

traction motors mounted on the trucks (bogies). In older locomotives, the alternator was

a DC machine, called a generator. It produced direct current which was used to provide

power for DC traction motors. Many of these machines are still in regular use. The next

development was the replacement of the generator by the alternator but still using DC

traction motors. The AC output is rectified to give the DC required for the motors.

4.2 Auxiliary Alternator

Locomotives used to operate passenger trains are equipped with an auxiliary

alternator. This provides AC power for lighting, heating, air conditioning, dining

facilities etc. on the train. The output is transmitted along the train through an auxiliary

power line. In the US, it is known as "head end power" or "hotel power". In the UK, air

conditioned passenger coaches get what is called electric train supply (ETS) from the

auxiliary alternator.

4.3 Motor Blower

The diesel engine also drives a motor blower. As its name suggests, the motor

blower provides air which is blown over the traction motors to keep them cool during

periods of heavy work. The blower is mounted inside the locomotive body but the

motors are on the trucks, so the blower output is connected to each of the motors through

flexible ducting. The blower output also cools the alternators. Some designs have

separate blowers for the group of motors on each truck and others for the alternators.

Whatever the arrangement, a modern locomotive has a complex air management system

which monitors the temperature of the various rotating machines in the locomotive and

adjusts the flow of air accordingly.

4.4 Air Intakes

The air for cooling the locomotive's motors is drawn in from outside the locomotive. It

has to be filtered to remove dust and other impurities and its flow regulated by

temperature, both inside and outside the locomotive. The air management system has to

take account of the wide range of temperatures from the possible +40 C of summer to

the possible -40 C of winter.

4.5 Rectifiers/Inverters

The output from the main alternator is AC but it can be used in a locomotive with

either DC or AC traction motors. DC motors were the traditional type used for many

years but, in the last 10 years, AC motors have become standard for new locomotives.

They are cheaper to build and cost less to maintain and, with electronic management can

be very finely controlled. To see more on the difference between DC and AC traction

technology try the Electronic Power Page on this site.

To convert the AC output from the main alternator to DC, rectifiers are required. If the

motors are DC, the output from the rectifiers is used directly. If the motors are AC, the

DC output from the rectifiers is converted to 3-phase AC for the traction motors.

In the US, there are some variations in how the inverters are configured. GM

EMD relies on one inverter per truck, while GE uses one inverter per axle - both systems

have their merits. EMD's system links the axles within each truck in parallel, ensuring

wheel slip control is maximized among the axles equally. Parallel control also means

even wheel wear even between axles. However, if one inverter (i.e. one truck) fails then

the unit is only able to produce 50 per cent of its tractive effort. One inverter per axle is

more complicated, but the GE view is that individual axle control can provide the best

tractive effort. If an inverter fails, the tractive effort for that axle is lost, but full tractive

effort is still available through the other five inverters. By controlling each axle

individually, keeping wheel diameters closely matched for optimum performance is no

longer necessary.

4.6 Electronic Controls:

Almost every part of the modern locomotive's equipment has some form of

electronic control. These are usually collected in a control cubicle near the cab for easy

access.

The controls will usually include a maintenance management system of some

sort which can be used to download data to a portable or hand-held computer.

Fig.9 Controls, indicators and the radio

4.7 Control Stand

This is the principal man-machine interface, known as a control desk in the UK

or control stand in the US. The common US type of stand is positioned at an angle on the

left side of the driving position and, it is said, is much preferred by drivers to the modern

desk type of control layout usual in Europe and now being offered on some locomotives

in the US.

4.8 Batteries

Just like an automobile, the diesel engine needs a battery to start it and to provide

electrical power for lights and controls when the engine is switched off and the alternator

is not running.

The locomotive operates on a nominal 64-volt electrical system. The locomotive has

eight 8-volt batteries; each weighing over 300 pounds (136 kg). These batteries provide

the power needed to start the engine (it has a huge starter motor), as well as to run the

electronics in the locomotive. Once the main engine is running, an alternator supplies

power to the electronics and the batteries.

4.9 Cab

Most US diesel locomotives have only one cab but the practice in Europe is two

cabs. US freight locos are also designed with narrow engine compartments and

walkways along either side. This gives a reasonable forward view if the locomotive is

working "hood forwards". US passenger locos, on the other hand have full width bodies

and more streamlined ends but still usually with one cab. In Europe, it is difficult to tell

the difference between a freight and passenger locomotive because the designs are almost

all wide bodied and their use is often mixed. The cab of the locomotive rides on its own

suspension system, which helps isolate the engineer from bumps. The seats have a

suspension system as well.

4.10 Traction Motor

Since the diesel-electric locomotive uses electric transmission, traction motors are

provided on the axles to give the final drive. These motors were traditionally DC but the

development of modern power and control electronics has led to the introduction of 3-

phase AC motors. There are between four and six motors on most diesel-electric

locomotives. A modern AC motor with air blowing can provide up to 1,000 hp.

Propulsion: The traction motors provide propulsion power to the wheels. There is one

on each axle. Each motor drives a small gear, which meshes with a larger gear on the axle

shaft. This provides the gear reduction that allows the motor to drive the train at speeds of

up to 110 mph.

Fig. 10 Traction Motor

Each motor weighs 6,000 pounds (2,722 kg) and can draw up to 1,170 amps of electrical

current.

4.11 Fuel Tank

A diesel locomotive has to carry its own fuel around with it and there has to be

enough for a reasonable length of trip. The fuel tank is normally under the loco frame

and will have a capacity of say 1,000 imperial gallons (UK Class 59, 3,000 hp) or 5,000

US gallons in a General Electric AC4400CW 4,400 hp locomotive. The new AC6000s

have 5,500 gallon tanks. In addition to fuel, the locomotive will carry around, typically

about 300 US gallons of cooling water and 250 gallons of lubricating oil for the diesel

engine. Air reservoirs are also required for the train braking and some other systems on

the locomotive. These are often mounted next to the fuel tank under the floor of the

locomotive.

This huge tank in the underbelly of the locomotive holds 2,200 gallons (8,328 L)

of diesel fuel. The fuel tank is compartmentalized, so if any compartment is damaged or

starts to leak, pumps can remove the fuel from that compartment.

4.12 Governor

Once a diesel engine is running, the engine speed is monitored and controlled through a

governor. The governor ensures that the engine speed stays high enough to idle at the

right speed and that the engine speed will not rise too high when full power is demanded.

The governor is a simple mechanical device which first appeared on steam engines. It

operates on a diesel engine as shown in the diagram below.

The governor consists of a rotating shaft, which is driven by the diesel engine. A pair

of flyweights is linked to the shaft and they rotate as it rotates. The centrifugal force

caused by the rotation causes the weights to be thrown outwards as the speed of the shaft

rises. If the speed falls the weights move inwards. The flyweights are linked to a collar

fitted around the shaft by a pair of arms. As the weights move out, so the collar rises on

the shaft. If the weights move inwards, the collar moves down the shaft. The movement

of the collar is used to operate the fuel rack lever controlling the amount of fuel supplied

to the engine by the injectors.

Fig. 11 Principle of Governor

4.12.1 Function and types of governors

The purpose of a governor is to control the speed of an engine. If an engine is loaded beyond its rated capacity, it will slow down or may even stop. Governors act through the

fuel injection system to control the amount of fuel delivered to the cylinders. The

quantity of fuel delivered, in turn, governs the power developed.

The two types of governors, each of which serves a distinctly different purpose, are :

over speed governor and regulating governor. The over speed type is used on most

marine engines where the speed of the engine is variable. By necessity, the marine engine

requires flexibility in speed due to the maneuvering of the ship. This type of governor is

installed as a safety measure and comes into action when the engine approaches

dangerous over speed. This condition could occur before the operator had time to bring

the engine under control by other means. The over speed trip functions only if the

regulating governor fails. This governor controls all abnormal speed surges.

Overspeed governors are of the centrifugal type; that is, the action of the governor

depends upon the centrifugal force created as the governor weights revolve. Centrifugal

force is the force that tends to move a body away from the axis about which it is

revolved. This force is transmitted to the fuel injection system by means of levers

connected to the governor collar and a linkage system. In some types of over speed

governors the action merely cuts off the fuel until the engine has slowed to a point of

safety and then allows the resumption of normal operation. The other type trips a fuel

cutout mechanism and affects a complete stopping of the engine. The F-M engines

employ an F-M design over speed governor and the GM engines use Woodward over

speed governors.

For this discussion governors will be classified as either hydraulic or mechanical.

The mechanical type embodies the principle of centrifugal force similar to the over speed

type, while the hydraulic type employs a centrifugally actuated pilot valve to regulate the

flow of a hydraulic medium under pressure. The mechanical governor is more applicable

to the small engine field not requiring extremely close regulation while the hydraulic type

finds favor with the larger installations demanding very close regulation. The regulating

governor is much more sensitive to slight speed fluctuations than is the overspeed

governor. Its duty is to control the speed within very narrow limits when an engine is

operating under varying loads. It takes the place of the operator's manual control of the

throttle. When the load on the engine increases, and before the engine's speed has

appreciably dropped, it permits an increase of fuel to the cylinders, thus maintaining the

engine speed at the set rate. To perform this function, the governor must be sensitive to

the slightest variation in speed. The Woodward hydraulic governor of the regulating type

is widely used in the United States Navy & Railway Engines.

4.12.2 Description and operation

The type of regulating governor used on all submarine main engines is the

Woodward SI hydraulic type governor. On F-M engines, it is driven from the lower

crankshaft, and on GM engines, from one of the camshafts. The purpose of the governor

is to regulate the amount of fuel supplied to the cylinders so that a predetermined engine

speed will be maintained despite variations in load. Figure 10-2 is a schematic diagram of

the governor. The principal parts of the governor are a gear pump and accumulators

which serve to keep a constant oil pressure on the system at all times; a pilot valve

plunger, pilot valve bushing, and flyweights which control the amount of oil going to the

power assembly; a speed adjusting spring whose tension governs the speed setting of the

governor; the power element, consisting of the power spring, power piston, and power

cylinder; and the compensating assembly which consists of the actuating compensating

plunger, the receiving compensating plunger, the compensating spring, and two

compensation needle valves. The pilot valve plunger is constructed with a land which

serves to open or close the port in the pilot valve bushing leading to the power cylinder.

In this governor the flyweights are linked hydraulically to the fuel control

cylinder. The downward pressure of the power spring is balanced by the hydraulic lock

on the lower side of the power piston. The amount of oil below the power piston is

regulated by the pilot valve plunger controlled by the flyweights.

Fig. 12 Woodward regulating governor installed

When the engine is running at the speed set on the governor, the land on the pilot

valve plunger covers the regulating port in the bushing. The plunger is held in this

position by the flyweights. However, if the engine load decreases, the engine speeds up

and the additional centrifugal force moves the flyweights outward, raising the pilot valve

plunger. This opens the regulating port of the bushing, and trapped oil from the power

cylinder is then allowed to flow through the pilot valve cylinder into a drainage passage

to the oil sump. As the trapped oil drains to the oil sump, the power spring forces the

piston down, actuating the linkage to the fuel system controls, and the supply of fuel to

the engine is diminished. As the engine speed returns to the set rate, the flyweights

resume their original position and the, pilot valve plunger again covers the regulating

port.

Fig. 13 Schematic diagram of Woodward regulating governor

If the load increases, the engine slows down, and the flyweights move inward. This

lowers the pilot valve plunger, allowing pressure oil to flow through the pilot valve

chamber to the power cylinder. This oil supplied by a pump is under a pressure sufficient

to overcome the pressure of the power spring. The power piston moves upward, actuating

the linkage to increase the amount of fuel injected into the engine cylinders. Once again,

as the speed returns to the set rate, the flyweights resume their central position. The gear

pump that supplies the high-pressure oil is driven from the governor drive shaft and takes

suction from the governor oil sump. A spring-loaded accumulator maintains a constant

pressure of oil and allows excess oil to return to the sump.

To prevent overcorrection in the regulating governor a compensating mechanism

is used. This acts on the pilot valve bushing so as to anticipate the pilot valve movement

and close the regulating port slightly before the centrifugal flyballs would normally direct

the pilot valve to cover the port. A compensating plunger on the power piston shaft

moves in a cylinder that is also filled with oil. When the engine speed increases and the

power piston moves downward, the actuating compensating plunger is also carried down,

drawing oil into its cylinder. This creates a suction above the receiving compensating

plunger which is part of the pilot valve bushing. The bushing moves upward, closing the

port to the power piston. Thus the power piston is stopped, allowing no time for

overcorrection. As the flyweights and pilot valve return to their central position, oil

flowing through a needle valve allows the compensating spring to return to its central

position. To keep the port closed, the bushing and plunger must return to normal position

at exactly the same speed. Therefore, the needle valve must be adjusted so that the oil

passes through at the required rate for the particular engine.

When the engine speed drops below the set rate, the actuating compensating

plunger moves upward with the power piston. This increases the pressure above the

actuating compensating plunger and consequently above the receiving compensating

piston which therefore moves down, carrying with it the pilot valve bushing. As before,

the lower bushing port is closed. The excess oil in the compensating system is now forced

out through the needle valve as the compensating spring returns the bushing to its central

position.

The governing speed of the engine is set by changing the tension of the speed adjusting

spring. The pressure of this spring determines the engine speed necessary for the

flyweights to maintain their central position. Oil allowed to leak past the various plungers

for lubricating purposes is drained into the governing oil sump.

In actual operation, the events described above occur almost simultaneously.

4.12.3 Regulating governor sub-assemblies:-

The governor consists of five principal subassemblies as follows:

a. Drive adapter: - The drive adapter assembly serves as a mounting base for the

governor. The upper flange of the casting is bored out at the center to form a bearing

surface for the hub of the pump drive gear and for the upper end of the drive shaft.

b. Power case assembly:- This assembly includes the governor oil pump, oil pump

check valves, oil pressure accumulators, and compensating needle valves.

The oil pump drive gear turns the rotating sleeve to which it is attached. The

pump idler gear is carried on a stud and rotates in a bored recess in the power case. These

two gears and their housing constitute the governor oil pump. On opposite sides of the

central bore in the power case, and parallel to it, are two long oil passages leading from

the bottom of the power case to the top of the accumulator bores. Check valve seats are

arranged at the top and bottom of each chamber. Both check valves have openings

leading from the space between the valves to the oil pump. In this way the pump is

arranged for rotation in either direction, pulling oil through the lower check valve on one

side and forcing it through the upper check valve on the opposite side.

There are two oil pressure accumulators. Their function is to regulate the

operating oil pressure and insure a continuous supply of oil in the event that the

requirements of the power cylinder should temporarily exceed the capacity of the oil

pump. There is no adjustment for oil pressure, as this pressure is determined by the size

of the springs in the accumulators. The two compensating needle valves control the size

of the openings in the two small tapered ports in the passage that connects the area above

the actuating compensating plunger in the Servo motor and the space above the receiving

compensating plunger in the pilot valve bushing of the rotating sleeve assembly. These

ports open the compensating oil passage to the oil sump tank. Only one needle valve and

one port are necessary for operation, but two are provided so that adjustment can be made

on the one that is more accessible.

Fig. 14 Governor-sections through adapter, power, case, power cylinder and rotating sleeve assembly.

c. Power cylinder assembly: - The power cylinder assembly consists of the cylinder,

power piston, piston rod, power spring, and the actuating compensating plunger. The

power piston is single acting. Any oil pressure acting on the lower side forces the piston

up against the power spring, thereby increasing the fuel flow. If no oil pressure is present,

the power spring acting on the upper side forces the piston down to decrease the fuel

flow.

The area underneath the power piston is connected to the pilot valve regulating

ports. An oil drain is provided in the space above the power piston to permit any oil that

may leak by the piston to drain into the governor case oil sump. No piston rings are used

in the closely fitting piston. A shallow, helical groove permits equal oil pressure on all

sides of the piston, thus preventing wear and binding.

An adjustable load limit stop screw is provided in the power cylinder. This screw

prevents the power piston from traveling beyond the predetermined load limit. The screw

can be adjusted by removing the cap nut on top of the power cylinder, loosening the lock

nut, and turning the screw up or down with a screwdriver.

d. Speed control column:- The basic speed control column assembly includes the

speeder plug screw, speed adjusting spring, rack shaft, rack shaft gear, and the speed

adjustment knob with gear train. The gear train consists of the dial shaft gear, dial shaft

pinion, and the pinion shaft gear and pinion. Movement of the gear train changes the

compression of the speed adjusting spring. The amount of compression determines the

speed at which the flyballs will be vertical. Hence, the compression determines the

engine speed. The speeder plug screw allows the adjustment of the governor speed setting

to match the actual speed of the engine.

e. Rotating sleeve assembly: - The principal parts of the rotating sleeve assembly

(Figure 10-13) are: the pump drive gear, pilot valve bushing, pilot valve plunger,

ballhead, and flyballs. The central bore in the power case forms a bearing for the entire

rotating sleeve. The port grooves in the sleeve align with the ports in the power case

(Figure 10-10). Since these grooves extend completely around the diameter of the

rotating sleeve, the results are the same as if the sleeve were stationary and the ports were

permanently in line with those in the case. From top to bottom the ports are as follows:

accumulator pressure to pilot valve, regulating pressure to power cylinder, drain from the

lower end of the pilot plunger, compensating pressure from the power piston to the

receiving compensating plunger on the pilot valve bushing, and drain from the lower side

of the receiving compensating plunger.

4.12.4 ADJUSTMENTS

a. Speed adjustment: - The speed setting of the governor is changed by increasing or

decreasing the compression of the speed adjusting spring which opposes the centrifugal

force of the flyballs. Increasing the spring compression will make it more difficult for the

flyballs to move outward; consequently a higher flyball (and engine) speed must be

attained to move the flyballs outward and thereby reduce the fuel supply.

Conversely, decreasing the compression of the speed adjusting spring will permit

the flyballs to move outward when they, and the engine, are running at a lower speed.

Thus, decreasing the spring compression decreases the speed at which the engine will

run.

Speed adjustments may be made manually at the governor, or electrically from the

governor control cabinet in the maneuvering room as follows:

1. Manual adjustment:- The manual adjustment is made by means of the

speed control knob located on the front of the regulating governor. This knob is

connected through a gear train to the rack shaft which in turn is- geared to a rack on

the speed adjusting plug. The knob also actuates a pointer that travels over a dial

graduated to show engine speeds corresponding to deflection of the speed adjusting

spring.

2. Electrical adjustment:- For electrical control, a Selsyn receiving motor is

also geared to the rack shaft. This receiving motor operates in parallel with a Selsyn

transmitter generator in the governor control cabinet mounted on the main control

cubicle instrument panel in the maneuvering room. When the speed setting is

changed at the transmitter generator, the receiving motor in the governor moves to

establish the same setting in the governor.

b. Compensating needle valve adjustment:- This adjustment is made with the engine

running from 200 rpm to 300 rpm as set by the speed adjustment knob or by remote

control.

Either of the two needle valves may be used for adjustment. The one not used must be

turned in against its seat. When performing the adjustment, the more accessible valve is

opened a full turn or more and the engine is allowed to surge for approximately 30

seconds to eliminate trapped air. Then the valve is closed until surging is just eliminated.

The needle valve will usually be open about one-fourth of a turn for best performance.

However, the adjustment depends on the characteristics of the engine. The needle valve

should be kept open as far as possible to prevent sluggishness. Once the valve has been

adjusted correctly for the engine, it should not be necessary to change the adjustment

except for a permanent temperature change affecting the viscosity of the oil.

4.12.5 Air Compressor

The air compressor is required to provide a constant supply of compressed air for

the locomotive and train brakes. In the US, it is standard practice to drive the compressor

off the diesel engine drive shaft. In the UK, the compressor is usually electrically driven

and can therefore be mounted anywhere. The Class 60 compressor is under the frame,

whereas the Class 37 has the compressors in the nose.

4.12.6 Gear Box

The radiator and its cooling fan is often located in the roof of the locomotive.

Drive to the fan is therefore through a gearbox to change the direction of the drive

upwards.

4.12.7 Fuel Injection

Ignition is a diesel engine is achieved by compressing air inside a cylinder until it

gets very hot (say 400 C, almost 800 F) and then injecting a fine spray of fuel oil to

cause a miniature explosion. The explosion forces down the piston in the cylinder and

this turns the crankshaft. To get the fine spray needed for successful ignition the fuel has

to be pumped into the cylinder at high pressure. The fuel pump is operated by a cam

driven off the engine. The fuel is pumped into an injector, which gives the fine spray of

fuel required in the cylinder for combustion.

Fig. 15 Fuel injection pump Fig. 16 FIP cut section

The original fuel injection pumps used on ALCO Engines had plunger diameter of

15 mm. The plunger diameter of the fuel injection pump was increased from 15 mm to 17

mm. This modification led to sharper fuel injection i.e. injection at higher-pressure. The

modification resulted in increase of peak fuel line pressure from 750 to 850 bars and,

thus, improvement in the fuel efficiency.

The estimated fuel and lube oil economy with this modification is approx. 1.5%

and 4% respectively.

4.12.8 FIP Testing

Ensure the level of servo calibration. Oil is above the low mark in storage tank of

test stand.

Heat the oil to 100 F to 120 F.

Mount the m/c nozzle according to FIP type to be used on m/c.

Mount the overhauled FIP on cam housing & tighten. The FIP rack should be

against the spring loaded plunger.

Screw the fuel inlet union.

Connect the high pressure tube b/w FIP discharge & calibrating nozzle.

Keep the control rack in full fuel oil position & insert horse shoe space according

to FIP type to be tested b/w the rack positioning tool & FIP face.

Reset the counter to zero.

Operate the calibrating m/c & set the oil pressure 25-30 psi.

Measure the oil delivery in beaker for 300 strokes. Do this process five times &

check the average of last three measurement of oil delivery.

If specified delivery is not achieved adjust the rack by rotating rack position tool

in the required direction to get the specified delivery & when it is found within

specified limit, stop the m/c.

Adjust the pointer of full fuel position to proper mm reading. Remove the horse

shoe space & ensure rack length is at idle fuel length i.e. at 9 mm & record the full

fuel delivery in calibration data nozzle.

4.12.9 Injector Assembly Sequence

1. Nozzle holder body.

2. Compensating washer.

3. Spring.

4. Spindle with guide bush.

5. Intermediate disc.

6. Nozzle.

7. Nozzle cap nut.

4.12.9.1 Maintenance Instruction Of Injector While Re-Conditioning

Nozzle value lift 0.024 max.

Testing pressure

Min. 3100 Psi-260 kg/cm

Max. 4100 Psi-290 kg/cm

Spring pattern should be uniform.

Nozzle should give healthy chartering sound.

Seat tightness test, there should be no dribbling.

4.12.9.2Tool, Gauges, Torque Wrenches Used In FIP Section

Torque Wrench 100 to 400 ft. lbs.

Torque Wrench 450 to 750 ft. lbs.

Socket 1 () & 2(()

Box Spanner 36 mm & 70 mm.

Reamer 23/32 HSS.

Centering Sleeve For Injector Nozzle.

True Running Tool For Injection.

Pin Vice Kit.

Dial Gauge.

Temp. Gauge 0 to 110 C.

Pressure Gauge 0 to 100 psi.

Pressure Gauge 0 to 8960 psi.

Nose Plier.

Clean all the components once again using clean HSD oil & assemble them wet.

Place the injector nozzle holder body in the fixture with nozzle & upward.

Position the spring seat & spring in the body.

Keep spindle with guide bush & intermediate disc on spring.

Place assemble nozzle over the intermediate disc & screw the nozzle cap nut &

torque to 105 ft. lbs.

4.13 Fuel Control

In an automobile engine, the power is controlled by the amount of fuel/air mixture

applied to the cylinder. The mixture is mixed outside the cylinder and then applied by a

throttle valve. In a diesel engine the amount of air applied to the cylinder is constant so

power is regulated by varying the fuel input. The fine spray of fuel injected into each

cylinder has to be regulated to achieve the amount of power required. Regulation is

achieved by varying the fuel sent by the fuel pumps to the injectors.

Fig. 17 Fuel System

The amount of fuel being applied to the cylinders is varied by altering the effective

delivery rate of the piston in the injector pumps. Each injector has its own pump,

operated by an engine-driven cam, and the pumps are aligned in a row so that they can all

be adjusted together. The adjustment is done by a toothed rack (called the "fuel rack")

acting on a toothed section of the pump mechanism. As the fuel rack moves, so the

toothed section of the pump rotates and provides a drive to move the pump piston round

inside the pump.The fuel rack can be moved either by the driver operating the power

controller in the cab or by the governor. If the driver asks for more power, the control

rod moves the fuel rack to set the pump pistons to allow more fuel to the injectors. The

engine will increase power and the governor will monitor engine speed to ensure it does

not go above the predetermined limit.The limits are fixed by springs limiting the weight

movement.

Fig.18 Fuel Supply system

4.14 Radiators

They are used for cooling internal combustion engines, chiefly in automobiles but

also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating

plant or any similar use of such an engine.

They operate by passing a liquid coolant through the engine block, where it is heated,

then through the radiator itself where it loses this heat to the atmosphere. This coolant is

usually water-based, but may also be oil. It's usual for the coolant flow to be pumped,

also for a fan to blow air through the radiator.

In railway with a liquid-cooled internal combustion engine a radiator is connected to

channels running through the engine and cylinder head, through which a liquid (coolant)

is pumped. This liquid may be water (in climates where water is unlikely to freeze), but is

more commonly a mixture of water and antifreeze in proportions appropriate to the

climate. Antifreeze itself is usually ethylene glycol or propylene glycol (with a small

amount of corrosion inhibitor).

The radiator transfers the heat from the fluid inside to the air out