This document provides a summary of the author's 24-week training experience at Sri Lanka Railways. It begins with acknowledging those who helped facilitate the training program. The body discusses various areas of training, including locomotive repair, electrical systems, traffic control, machining, and more. It provides technical details on topics like diesel engine components, traction motors, signaling equipment, and lathe operation. The conclusion reflects on the overall training and makes suggestions for improving future programs.

1. i
Acknowledgement
First of all, I would like to thanks to HOD of University of Vocational Technology Eng.
S.P.A.R.S. Jayathilaka, and also the officers of the NAITA for helping me from the placement
at the organization until the end of the training period.
I would like to give my sincere gratitude to Training Director Mr. A.D.
Wickramasinghe and Training Operational Manager Mrs. S.H.M.P.Y. Samarasinghe. Of Sri
Lanka German Railway Technical Training Center for accepting me as an apprentice and
providing all the facilities for the training period of 24 weeks. And also, I would like thanks
for Chief Mechanical Engineer Mr. W.G.D.L. Wickramathunge, Deputy Mechanical Engineer
K.G.S. Bandara of Chief Mechanical Engineering Office Rathmalana and Signal Engineer Mrs.
M.A.N Sugandi.
Also, I am grateful to all foreman, Supervisors, Technicians and Labors of Workshops
14,35,39,41, STE,16,27,28 of Chief Mechanical Engineering Office Rathmalana.
J.R.A Shantha
MEC/16/B1/10
Department of electrical and electronics
University of Vocational Technology.

2. ii
Preface
In this report included my experience and training knowledge which I was established to
training program at Sri Lanka Railways from 25th
June 2018 to 24th
December 2018.The
content of this report has main three chapters. The first one is introduction to the training
establishment. The second one is training experience that I have from Sri Lanka Railways.
Then finally conclusion
First chapter provides a short introduction about the training establishments. I have
visited their organizational structures. The present performance of Chief Mechanical
Engineering Workshops Rathmalana and STE unit in Dematagoda of Sri Lanka Railways.
Also, it contains the details about the project works done and other observed and learnt things.
The final chapter is the conclusion, which summarizes the training experience. In
addition to that, suggestions to improve the training program are added to the chapter. It will
describe about the entire training assessment in order to give an overall idea about the 24 weeks
training program at Sri Lanka Railways.

3. iii
Table of Contents
1 Sri Lanka Railways............................................................................................................1
1.1 Introduction to The Training Establishment ...............................................................1
1.1.1 Introduction..........................................................................................................2
1.1.2 Present Performance ............................................................................................2
1.1.3 Vision & Mission of Sri Lanka Railways............................................................3
1.1.4 Structure of Sri Lanka Railways..........................................................................3
1.1.5 Strengths and weakness .......................................................................................4
1.1.6 Opportunities for Improvement ...........................................................................4
1.1.7 Profitability ..........................................................................................................4
1.1.8 Threats for Its Survival ........................................................................................5
1.1.9 Usefulness to the Country....................................................................................5
1.1.10 Suggestions to improve........................................................................................5
1.1.11 EPF (Employees’ Provident Fund) ......................................................................6
1.1.12 ETF (Employees’ Trust Fund).............................................................................6
1.1.13 Leave procedures .................................................................................................6
2 Training Experience...........................................................................................................7
2.1 Diesel Electric Locomotive Repair (2 stroke).............................................................7
2.1.1 How Locomotive Engine Transmit Power to Wheels .........................................7
2.1.2 Working Principal of Two Stroke Diesel Engine ................................................7

4. iv
2.1.3 Locomotive Governor..........................................................................................8
2.1.4 Cylinders of 2 Stroke Engine...............................................................................9
2.1.5 Two Stroke Engines Firing Order........................................................................9
2.1.6 Injector Pump Calibration..................................................................................10
2.2 Electronic Controls, DC Electrical Machines & Rewinding.....................................10
2.2.1 DC Motors .........................................................................................................12
2.2.2 Rewinding..........................................................................................................14
2.3 Heavy AC & DC Generators, Traction Motors.........................................................15
2.3.1 Traction Motors .................................................................................................16
2.3.2 Control Cubical Works ......................................................................................21
2.3.3 Armature balancing............................................................................................22
2.4 Traffic Control Systems ............................................................................................25
2.4.1 Interlocking system............................................................................................27
2.4.2 Wayside Signalling Equipment..........................................................................30
2.4.3 Track switching (Point Machines).....................................................................31
2.4.4 VHF/UHF Radio Network & Optical Fibre Communication System...............33
2.5 Bench Fitting and Machining....................................................................................36
2.5.1 Lathe Machines..................................................................................................37
2.5.2 Shaping Machine ...............................................................................................39
2.5.3 Planning Machine ..............................................................................................40

5. v
2.5.4 Drilling Machines ..............................................................................................40
2.6 Tool Room.................................................................................................................41
2.6.1 Cutting Tool Making..........................................................................................41
2.6.2 Gear Wheel Cutting ...........................................................................................43
2.6.3 Profile Tool........................................................................................................44
2.6.4 Engraving Machine............................................................................................44
2.7 Diesel Electric Locomotive Repair (4 stroke)...........................................................45
2.7.1 Working Principle of 4 Stroke Diesel Engine....................................................45
2.7.2 Piston Rings .......................................................................................................45
2.7.3 Sleeves of 4 Stroke Engine ................................................................................46
2.7.4 Generator Alignment for the Crankshaft ...........................................................46
2.7.5 Crankshaft Installation.......................................................................................47
2.8 Diesel Engine Auxiliaries..........................................................................................47
2.8.1 Air Compressors, Exhauster and Expressor.......................................................47
2.8.2 Radiators and Intercoolers .................................................................................49
2.8.3 Turbochargers and superchargers ......................................................................50
2.9 Diesel Hydraulic Locomotive Repair........................................................................51
2.9.1 Power Transmitting Through Torque Converter ...............................................51
2.9.2 Torque Converter...............................................................................................51
2.9.3 Timing of Engine ...............................................................................................52

6. vi
2.9.4 Wheel and Underframe......................................................................................52
2.9.5 What is Bogie.....................................................................................................52
2.9.6 Brake Hoses .......................................................................................................54
2.10 Inspection...............................................................................................................54
3 Conclusion .......................................................................................................................55

7. vii
Figures
Figure 1: engine with genarator .................................................................................................7
Figure 2:Traction motor.............................................................................................................7
Figure 3: 2 Stroke Cylinder........................................................................................................8
Figure 4: 2 Stroke Engine Block................................................................................................8
Figure 5: Fuel Rack Lever .........................................................................................................9
Figure 6: Loco Governor ...........................................................................................................9
Figure 7: V12 Firing Order........................................................................................................9
Figure 8: V8 Firing Order..........................................................................................................9
Figure 9: Injector Pump Testing Machine ...............................................................................10
Figure 10: Injector Pumps........................................................................................................10
Figure 11:Loco HMI................................................................................................................11
Figure 12: DC motor................................................................................................................13
Figure 13:Rewinding motor.....................................................................................................14
Figure 14: Loco comiutetator...................................................................................................15
Figure 15: Traction motor........................................................................................................16
Figure 16: Motor schematic.....................................................................................................18
Figure 17: Schematic of a simple traction motor power control circuit. .................................19
Figure 18: Schematic showing a DC traction motor control circuit with notching, overload and
no-volt relays. ..........................................................................................................................20

8. viii
Figure 19: Apparatus of the Control Cubicle...........................................................................21
Figure 20: Traction motor controller .......................................................................................22
Figure 21: Armature balancing................................................................................................23
Figure 22:Traffic control room................................................................................................25
Figure 23: Train tracking monitor............................................................................................25
Figure 24: Srilanka traffic map................................................................................................26
Figure 25: Mechanical inter locking........................................................................................28
Figure 26: Relay room .............................................................................................................28
Figure 27: Electronic control interlocking system...................................................................30
Figure 28: Track changer.........................................................................................................31
Figure 29: Way side signal ......................................................................................................32
Figure 30: signal communication system ................................................................................34
Figure 31: Fibre optic communication system.........................................................................36
Figure 32: Center Lathe ...........................................................................................................37
Figure 33: Turret Lathe............................................................................................................37
Figure 34: Headstock ...............................................................................................................37
Figure 35/; Headstock..............................................................................................................38
Figure 36: Tailstock .................................................................................................................38
Figure 37: Four Way Tool Post ...............................................................................................38
Figure 38: One Way Tool Post ................................................................................................38

9. ix
Figure 39: 4 Jaw Chuck ...........................................................................................................39
Figure 40: 3 Jaw Chuck ...........................................................................................................39
Figure 41: 4 Jaw Chuck ...........................................................................................................39
Figure 42: Planning Machine...................................................................................................40
Figure 43: Radial Arm Drill.....................................................................................................40
Figure 44: Cutting Tool ...........................................................................................................41
Figure 45: Side View of a Tool................................................................................................41
Figure 46: Top View of a Tool ................................................................................................42
Figure 47: End View of a Tool ................................................................................................42
Figure 48:Figure 2.23- Furnaces..............................................................................................43
Figure 49: Milling Machine.....................................................................................................43
Figure 50:Divide Head.............................................................................................................43
Figure 51: Profile Tool.............................................................................................................44
Figure 52: Engraving Machine ................................................................................................44
Figure 53: Piston Rings............................................................................................................45
Figure 54: M8 Engine Sleeves.................................................................................................46
Figure 55: Bedding Bar............................................................................................................47
Figure 56: Air Compressor ......................................................................................................48
Figure 57: Expresser ................................................................................................................48
Figure 58: Radiator ..................................................................................................................49

10. x
Figure 59: Turbocharger ..........................................................................................................50
Figure 60: -Turbocharger.........................................................................................................50
Figure 61:-Turbine of Torque Converter .................................................................................51
Figure 62:Torque Converter ....................................................................................................51
Figure 63: DC Motors on Bogie ..............................................................................................53
Figure 64: M10 Bogie Center ..................................................................................................53
Figure 65: Completed M4 Bogie .............................................................................................53
Figure 66: Brake Hangers........................................................................................................53
Tables
Table 1 : Training schedule........................................................................................................1
Table 2: Organization chart .......................................................................................................3

11. 1
1 Sri Lanka Railways
1.1 Introduction to The Training Establishment
In the Final year of the studies every B Tec Engineering undergraduate of University
of Vocational Technology Ratmalana should complete an industrial training.24 weeks’ employ
in the state or private company which is recognized by Industrial Training Division and
NAITA. The training program was supervised by Industrial Training Division of University
and NAITA.
I had my industrial training at Sri Lanka Railways. The training schedule provided is
shown in following table
No Section Period (weeks)
1 Diesel Electric Loco Repair (2 Stroke) 14 01
2 Electronic Controls, DC Electrical Machines & Rewinding
35
03
3 Heave AC & DC Generators, Traction Motors, DC
Traction Controls and Control Cubical Works, Armature
balancing. 39
02
4 Bench Fitting & Machining. 41 03
5 Traffic Control Systems, Interlocking system & Wayside
Signaling Equipment, VHF/UHF Radio Network, Optical
Fiber Communication System etc.
08
6 Diesel Electric Loco Repair (4 Stroke) 16 01
7 Motors & AC Main Generators, Locomotive Wiring 27 03
8 Diesel Hydraulic Loco Repair 28 02
Table 1 : Training schedule
Figure 1.1

12. 2
1.1.1 Introduction
1.1.1.1 HISTORY
Sri Lanka Railway introduced to Sri Lanka in 1864 for transport coffee from state of
up country of Kandy to port city of Colombo.With the development of tea plantations
in 1880s .Tea plantation grooved rapidly.To transport tea wanted more railway
facilities. Then builded more and more railways in Kandyan highlands. Also it was
providing service for transport to labour, machinery, manure, rice etc.Railway also
serviced to coconut plantaion in the west, south west and northwest and wet inland
rubber plantaion below the tea belt.
Ancient city of Anuradhapura attach to the main line to go further north Kankasanturai
To transport indian labours to ta and rubber plantations and import rice and other food
stuff from india Talaimannar connect to the main line.
Towards the east, strategically worthwhile connect a line to main line from natural
harbor Trincomalee and east province capital city Baticoloa. Also a line for Nanu Oya
and around Nuwara eliya tea plantations connect to the main line.
1.1.1.2 OVERVIEW
Sri Lanka railways is a government department functioning under the ministry of
transport It is the only rail transport service in Sri Lanka. Sri Lanka Railway daily
transport both passengers and cargo.
Sri Lanka Railways has 1561km rail tracks,72 locomotive engines,78 power sets 565
carriages and signaling network, at now workforce is 17634.
1.1.2 Present Performance
Sri Lanka railways has many numbers of locomotive engines and rail carriages. These are made
by different countries with different technologies. In this Chief Mechanical Engineering
workshops do heavy repair and maintenance of loco engines and carriages. Some parts are made
in workshops and others have buy from outside. Also, this workshop helps to made new
technicians for itself.

13. 3
1.1.3 Vision & Mission of Sri Lanka Railways
 The Vision
“To be the most sought-after land transport provider in Sri Lanka providing unsurpassed value
to our stakeholders”
 The Mission
“Provision of safe. reliable and punctual rail transport service for both passenger and freight
traffic, economically and efficiently”
1.1.4 Structure of Sri Lanka Railways
CME
DME
CEE
MED
MEC
CME
CME
CME
MES
MEW
MEF
MEL(E)
MEP
Foreman
MEL(H)
MEL(P)
Foreman Foreman
TKC
Trainees
Supervisor
TKC
Trainees
Technician
Technician
Technician
Labour
Technician
Technician
Technician
Labour
Table 2: Organization chart
Figure 1.2

14. 4
1.1.5 Strengths and weakness
 Strengths
 It is a government Organization
 Has lot of engines that made by Germany and USA with excellent technology
 Talented and experienced technical staff
 Quality and reliability machines at the workshops
 Employer satisfaction (good salary etc.)
 Weaknesses
 Very slow procurement process
 Very low efficiency working
 Oversized staff
 Bureaucracy
1.1.6 Opportunities for Improvement
SRL has oversize employers. It has to reduce. I saw very slow working. Lot of tasks pass the
deadline. So, have to make good working process for employers. It is very useful if change the
electrical trains to from typical diesel locomotives. Because diesel locomotives have expensive
maintenance system.
1.1.7 Profitability
It is not profitability. Government treasure every year pump millions for Sri Lanka Railways.
This is the only railway in Sri Lanka. So, it has no competitors. It has to do something. I think
it is very easy to make profitable. it beacause.it hasn’t any competitors.

15. 5
1.1.8 Threats for Its Survival
SRL has lot of threats for its survival. It has lot of employers. Also, it run with very old
technologies that exist since British era. So, its lower the working speed. One of the greatest
threats I saw is lot of workers haven’t safety methods for. In casting, machining, fittings, etc.
And their old workers only talented they have more knowledge and skills. But new workers
haven’t knowledge and skills. It is not problem of the experience I think it is a problem of
currently running training program of SRL.
1.1.9 Usefulness to the Country
Sri Lanka has huge population. And lot of them want public transportation it is covered by
buses and trains. So, trains do major part of public transport. It is covered lot of areas of Sri
Lanka. North to south. Eastern to western. Transport in train is low costly. And comfortable
than buses. It transports huge number of people of hundreds of tons of cargo or oil. It is also
help to distribution of oils posts and cargos. So, Sri Lanka Railways do major of transportation
of Sri Lanka
1.1.10Suggestions to improve
I think its employees are oversized. So, it has to reduced. It’s some progresses do with very old
technologies. It has to change with automation, CNC etc., Some workshops have more capacity
than needed to SRL. So Those workshops can production for outside (example foundry
workshop). In the world diesel locos out running. So, if SRL can change to electric locos it
very useful. it will reduce engine repairs, cost of lubricant diesel and other cost, Electric locos
are speed than diesel loco. So it is very useful for people of the country.

16. 6
1.1.11EPF (Employees’ Provident Fund)
The Employees Provident Fund (EPF) was established under the Act No. 15 of 1958 and is
currently the largest Social Security Scheme in Sri Lanka. With a current asset base of Rs.1,300
billion, the EPF is a little "Peace of Mind" for the employees of institutions and establishments
of the Private Sector, State Sponsored Corporations, Statutory Boards and Private Business.
The aim of the EPF is to assure financial stability to the employee in the winter of life and to
reward the employee for his or her role in the economic growth of the country. According to
the EPF act, the employee will contribute monthly 8% of the salary to the EPF and the company
will contribute 12%.
1.1.12ETF (Employees’ Trust Fund)
The ETF Board was established under Act No-46 of 1980 and commenced operations on 1st
March 1981. It was established under the Ministry of Labour and brought under the Ministry
of Finance in 1997. All public-sector employees who are not entitled to the Govt. Pension
Scheme and all private sector employees are members of this Fund while their employers are
required to remit 3% of the gross earnings of their employees to the Fund, monthly. Hence,
unlike the EPF, only the employer makes a contribution on behalf of the employee/member
and hence, it is a non-contributory benefit to the member. An ETF contribution of 3% of the
salary will be made by the company monthly.
1.1.13Leave procedures
 Annual Leave – 21 days per year
 Casual Leave – 2 days for private purpose
 Short Leave – 2 times per month
 Study Leave – 6 days per year
 Medical Leave – 365 year

17. 7
2 Training Experience
2.1 Diesel Electric Locomotive Repair (2 stroke)
In this workshop 2 stroke diesel engines were servicing and repaired. I spend 1st
week in this
shop. Class M2, M6 and M7 locomotive are the two stroke locomotive engines. All parts of
locomotive are disassembled and some part send to other shops for repair.M2 and M6 have
V12 engine and M7 has V8 engine.
2.1.1 How Locomotive Engine Transmit Power to Wheels
It is not work like normal vehicle. The huge engine drives a generator and generator produce
the current for DC motors. DC motors are joined to the wheel shaft of bogie. Then DC motor
drive the wheels. Engine can’t give suitable torque through gear box to initial acceleration the
train. So, DC motor at lowest rpm give highest torque. Then DC motor can give initial torque
to acceleration.
2.1.2 Working Principal of Two Stroke Diesel Engine
In this engine 4 valve on the engine head for exhaust and other for injecting the Diesel. Air is
taking by the when piston go to BDC by wholes of cylinder. Then compressed. Diesel inject
to the compressed (also heated) air. Then piston go to BDC by power stroke. When go to the
BDC exhaust valve opened. Intake and exhaust are done simultaneously.
Figure 1: engine with genarator
Figure 2:Traction motor

18. 8
2.1.3 Locomotive Governor
There is a special component in every loco engine that we can’t find in typical engines. It is
governor. It does key role in engine controlling. Governor use when engine need constant speed
regardless the load. Normally locomotive has 8 speeds. When we put notch to one speed
governor keep the that speed. Not considering load variation. Governor is connecting to a shaft
that driven by engine. It is work with centrifugal force. Locomotives in SLR are electro-
hydraulic type. The flyweight mechanism operates a hydraulic valve, which in turn allows oil
into a hydraulic cylinder. The piston link to the fuel rack lever. In the electro-hydraulic type,
the flyweights actuate solenoids. The solenoids in turn operate the hydraulic valves. Finally,
the hydraulic system actuates the fuel rack lever Also governor checks turbocharger pressure.
If it is not perfect governor reduce the magnetic field of generator. In this workshop also
governor is repairing. They check governor working for speeds, field change of generator. And
governor oil pressure. Normally turbo charger presser is 15 lb/𝑖𝑛2
. Governer oil have to be 7
bar.
Wholes for intake
Figure 3: 2 Stroke Cylinder
Figure 4: 2 Stroke Engine Block

19. 9
2.1.4 Cylinders of 2 Stroke Engine
Two stroke engine’s cylinder has some significant differences compare to the four stroke
engines cylinder, this has wholes for the air intake. There isn’t sleeve. Inside this cylinder has
pipe for the water cooling. It is put in to the engine block and then piston installed to the crank
shaft.
2.1.5 Two Stroke Engines Firing Order
The firing order is the order of power delivery of cylinder of multi-cylinder reciprocating
engine. In diesel engine do it by furl injecting to the correct order. Firing order is very important
to engine. Correct firing order can minimize the engine vibrations.
2
1 7 3 5
8 4 6
1 9 5 4 8 12
7 6 10 23 11
FlyWheel
FlyWheel
Figure 6: Loco Governor Figure 5: Fuel Rack Lever
Figure 8: V8 Firing Order Figure 7: V12 Firing Order

20. 10
2.1.6 Injector Pump Calibration
There is a tiny room for injector pump calibrations in workshop 14. Injector pump is the device
that inject the fuel to the cylinders. It is driven by indirectly from crankshaft. Injector pump
calibration is so very important. If it is not, it can be reason for reduce engines maximum power
and maximum fuel efficiency. So It have to deliver right amount of fuel on right time on right
piston. When calibrating. Verify volume of fuel inject it for certain stroke and it is delivers
fuels at right time to right piston.
2.2 Electronic Controls, DC Electrical Machines & Rewinding
Microprocessor based locomotive controller receives the signals from speed and current
sensors and gives the signals required for controlling electrical power output of the main
Class M10 locomotive is powered by the diesel engine model DLW 251C 12V with a
power of 2300 Hp. Engine governor is a microprocessor based electronic governor which
controls the fuel amount and governs the engine speed at each notch according to the power
demanded by traction and auxiliaries.
Figure 10: Injector PumpsFigure 9: Injector Pump Testing Machine

21. 11
alternator which is similar to the function of the load controller of the conventional diesel
electric locomotives. Fuel amount at each notch is set by the position of fuel rack, which is set
at the correct position at each notch by the servo drive unit driven by the signals of the
microcontroller. The mechanical power output of the diesel engine is converted to electrical
energy through the traction alternator which is directly coupled to the diesel engine. The 3
phase AC output from the traction alternator is rectified to DC voltage by a rectifier panel. The
rectified DC output is fed to the traction motors through breaking contactor (BKT), Reverser
(REV) and power contactors.
Microprocessor based loco control system MEP-660 made by MEDHA servo drives (Pvt) ltd
India, is a centralized locomotive control system which controls locomotive operation as per
the drivers’ commands and the status of the input devices.
Traction alternator power output is controlled by the microcontroller according to the notch
position (power level demanded by the driver) by controlling the exciter armature current
(traction alternator field current) through IGBT. Microcontroller generates a PWM output
signal and it triggers the IGBT as required.
Figure 11:Loco HMI

22. 12
2.2.1 DC Motors
Radiator fan is operated through an eddy current clutch similar to that of class M8 locomotives.
Operation control of the clutch is according to the engine temperature through the
microcontroller. Radiator fan operates at two speed levels as in M8 locomotives. M10
locomotive also provided with 28 LAV-1 type vacuum/compressed air brake system which is
also
During dynamic brake operation, the PWM is developed by microcontroller according to the
master control handle position in the dynamic brake zone and the speed of the locomotive and
the PWM controls the traction motor field current. Auxiliary generator field current also
controlled by a PWM signal produced by the microcontroller MEP-660.
Auxiliary generator voltage, battery voltage, auxiliary generator armature current etc are
measured by voltage and current sensors and fed into microcontroller for monitoring of them.
Radiator fan is operated through an eddy current clutch similar to that of class M8 locomotives.
Operation control of the clutch is according to the engine temperature through the
microcontroller.
similar to that of M8 locomotives. Contrary to M8, all brake valves are panel mounted to
enhance the maintainability.

23. 13
Like every electromotor, a brushed DC motor consists of two main parts, the
rotor and the stator. The DC motor contains either permanent magnets (PMDC) or
electromagnetic windings (SWDC) on the stator, which is on the outside of the motor. On the
inside, the rotor or “armature” is located. The rotor contains the coil windings that are powered
by DC current. When powered by DC current a magnetic field is created around the rotor.
Rotation is caused by the fact that one side of the rotor is attracted by the magnetic field in the
stator and the other side is repelled.
Figure 12: DC motor
The rotation continues due to the commutator. Basically, this commutator manages the
direction of the flow of current and thereby the direction of the magnetic field, as shown in the
image to the right. When the rotor turns due to attraction and repulsion and the rotor becomes
horizontally aligned, both brushes will make contact with the opposite side of the commutator.
This way the current through the rotor is reversed. As a consequence, the magnetic field is
reversed. This process repeats itself as long as power is supplied to the DC motor.
2.2.1.1 DIFFERENT TYPES OF BRUSHED DC MOTORS.
1. Permanent Magnet DC motor.
2. Series motor.
3. Shunt motor.
4. Compound motor.

24. 14
2.2.2 Rewinding
Alternating current (AC) and direct current (DC) motors employ an insulated,
current-carrying coil essential to their operation. The traditional method for motor rewinding
involves removing the old coil, winding a new coil and varnishing.
2.2.2.1 REMOVAL
Old coils are removed by heating the stationary part of the motor (stator) in an oven. The
stator is kept in the oven at temperature of 650 degrees Fahrenheit for at least 10 hours or
until the winding insulation turns to ash.
2.2.2.2 WINDING
New coils are traditionally wound by hand by a technician on a coil winding machine. The
technician controls the wire tension, layering and number of turns on the coil, although there
is also a mechanical counter on the machine.
Figure 13:Rewinding motor
2.2.2.3 VARNISHING
The newly rewound coil is warmed in an oven, immersed in an epoxy varnish and baked in
an oven at a temperature of 300 degrees Fahrenheit for at least four hours. This procedure is
known as dip and bake.

25. 15
2.3 Heavy AC & DC Generators, Traction Motors
Generators are useful appliances that supply electrical power during a power outage
and prevent discontinuity of daily activities or disruption of transportation operations.
Generators are available in different electrical and physical configurations for use in different
applications. In the following sections, we will look at how a generator functions, the main
components of a generator, and how a generator operates as a secondary source of electrical
power in residential and transformational applications.
Figure 14: Loco comiutetator
An electric generator is a device that converts mechanical energy obtained from an external
source into electrical energy as the output.
It is important to understand that a generator does not actually ‘create’ electrical
energy. Instead, it uses the mechanical energy supplied to it to force the movement of electric
charges present in the wire of its windings through an external electric circuit. This flow of
electric charges constitutes the output electric current supplied by the generator. This
mechanism can be understood by considering the generator to be analogous to a water pump,
which causes the flow of water but does not actually ‘create’ the water flowing through it.

26. 16
The modern-day generator works on the principle of electromagnetic
induction discovered by Michael Faraday in 1831-32. Faraday discovered that the above flow
of electric charges could be induced by moving an electrical conductor, such as a wire that
contains electric charges, in a magnetic field. This movement creates a voltage difference
between the two ends of the wire or electrical conductor, which in turn causes the electric
charges to flow, thus generating electric current.
Figure 15: Traction motor
2.3.1 Traction Motors
The main factors that have driven the enormous development of the railway,
as any other means of transport, have been, and continue to be safety, speed and economy. On
top of all this, as every day passes, its environmental impact is minimum, if not zero. In the
case of the railway, one of the determining factors behind its development was the type of track
used, either because of its gauge or the materials used in its construction. At the start, these
were made of cast iron, but they turned out to be lacking in safety as they easily broke due to
their fragility. Towards the end of the 19th century steel began to be used as it was a less fragile
and much stronger material. Nowadays, plate track is a key element in the development of

27. 17
High-Speed trains making wooden sleepers a thing of the past. The rubber track mountings
which are currently used to support the tracks have led to enormous reductions in vibration and
noise both in the track and the rolling stock. Moreover, each country had a different track gauge
due to strategic reasons of commerce and defense. Today’s global markets leave no other
option but to standardize track gauges or failing that, to produce rolling stock that can be
adapted to the different gauges quickly and automatically.
The birth of the railway is linked to the birth of the steam engine, while the
tremendous development of the railway in the 20th century was linked to the electrification of
the railway lines. In addition, the diesel locomotive played a very important role because of its
autonomy, particularly on those lines where electrification was unviable. The rivalry between
these three types of locomotive was long and hard with each competing to see which was the
safest, fastest and cheapest
2.3.1.1 THE DC TRACTION MOTOR
Historically, the DC motor was the mainstay of electric traction drives on both electric
and diesel-electric rolling stock. Many examples are still in use around the world. The motor
consists of two parts, a rotating armature and a fixed field (Figure 1). The fixed field consists
of tightly wound coils of wire fitted inside the motor case. The armature is another set of coils
wound round a central shaft. It is connected to the field through "brushes" which are spring
loaded contacts pressing against an extension of the armature called the commutator. The
commutator collects all the terminations of the armature coils and distributes them in a circular
pattern to allow the correct sequence of current flow.

28. 18
Figure 16: Motor schematic
The two parts are joined electrically through the commutator. The commutator rotates with the
armature and provides the connection to the field coils through brushes. Diagram: Author. The
DC motor works because, simply put, when a current is passed through the motor circuit, there
is a reaction between the current in the field and the current in the armature which causes the
armature to turn. The armature and the field are connected in series and the whole motor is
referred to as "series wound.
A series-wound DC motor has a low resistance field and armature circuit. Because
of this, when voltage is applied to it, the current is high (Ohms Law: current =
voltage/resistance). The advantage of high current is that the magnetic fields inside the motor
are strong, producing high torque (turning force), so it is ideal for starting a heavy object like
a train. The disadvantage is that the current flowing into the motor has to be limited somehow,
otherwise the supply could be overloaded and/or the motor and its cabling could be damaged.
At best, the torque would exceed the adhesion and the driving wheels would slip. Traditionally,
resistors were used to limit the initial current.

29. 19
2.3.1.2 TRACTION CONTROLS
DC control circuit
As the DC motor starts to turn, the interaction of the magnetic fields inside it causes it to
generate a voltage internally. This "back voltage" opposes the applied voltage and the current
that flows is governed by the difference between the two. So, as the motor speeds up, the
internally generated voltage rises, the effective voltage falls, less current is forced through the
motor and thus the torque falls. The motor naturally stops accelerating when the drag of the
train matches the torque produced by the motors. To continue accelerating the train, resistors
are switched out in steps, each step increasing the effective voltage and thus the current and
torque for a little bit longer until the motor catches up. This can be heard and felt in older DC
trains as a series of clunks under the floor, each accompanied by a jerk of acceleration as the
torque suddenly increases in response to the new surge of current. When no resistor is left in
the circuit, the full line voltage is applied directly to the motor. The train's speed remains
constant at the point where the torque of the motor, governed by the effective voltage, equals
the drag - sometimes referred to as balancing speed. If the train starts to climb a grade, the
speed reduces because drag is greater than torque. But the reduction in speed causes the back
voltage to decline and thus the effective voltage rises - until the current forced through the
motor produces enough torque to match the new drag.
Figure 17: Schematic of a simple traction motor power control circuit.

30. 20
Most DC motor circuits are arranged to control two or four motors. The control range
is enhanced by changing the connections to the motors as the train accelerates. The system is
known as "series-parallel control”. The diagram shows the resistors and contactors used to
regulate the voltage across the motors. The resistance is cut out in steps normally in the
sequence shown for both series and parallel connections. Diagram: Author.
On an electric train, the driver originally had to control the cutting out of resistance manually
but, by the beginning of the First World War in 1914, automatic acceleration was being used
on multiple-unit trains. This was achieved by an accelerating relay (often called a "notching
relay") in the motor circuit which monitored the fall of current as each step of resistance was
cut out. All the driver had to do was select low, medium or full speed (called "shunt", "series"
and "parallel" from the way the motors were connected in the resistance circuit) and the
equipment would do the rest.
Motor Control and Protection
Figure 18: Schematic showing a DC traction motor control circuit with notching, overload and no-volt relays.
As described above, DC motors are controlled by a "notching relay" set into the power circuit
(Figure 3). But there are other relays provided for motor protection. Sharp spikes of current
will quickly damage a DC motor so protective equipment is provided in the form of an
"overload relay", which detects excessive current in the circuit and, when it occurs, switches

31. 21
off the power to avoid damage to the motors. Power is switched off by means of Line Breakers,
one or two heavy-duty switches similar to circuit breakers which are remotely controlled. They
would normally be opened or closed by the action of the driver's controller but they can also
be opened automatically by the action of the overload relay.
A further protective device is also provided in the classic DC motor control circuit. This is the
"no-volt" relay, which detects power lost for any reason and makes sure that the control
sequence is returned to the starting point (i.e. all the resistances are restored to the power
circuit) before power could be re-applied. This is necessary to ensure that too much current is
not applied to a motor which lost speed while current was off.
2.3.2 Control Cubical Works
Figure 19: Apparatus of the Control Cubicle
(1) Motor cut-out switch (released with master controller locking key)
(2) Overload and earth fault panel with indicator flags. Flags show Red when normal, and
White when tripped
(3) Earth fault isolating switch (sealed in NORMAL position)

32. 22
(4) Nineteen miniature circuit-breakers (function and rating as labelled). (Toggle is down for
ON, up for OFF)
Fuses; auxiliary generator (800 amp), battery (250 amp), main generator excitation (125
amp), lubricating oil-cooling water pump set (35 amp), exhauster and blowers (60 amp), main
pump set (125 amp), voltmeter (2 amp), cooler fan (160 amp)
No spare fuses for the above are carried on the locomotives. If a fuse ruptures, the matter
should be reported at once. The defective fuse must not be replaced until the cause of the
rupture has been thoroughly investigated. Severe damage to machines or apparatus may be
caused otherwise.
A spare fuse of each type is carried, and these can be changed if necessary; boiler fuses (on
boiler control panel, low down on the right-hand side), magneto motor fuse (5 amp), boiler
and feed-water pump (20 amp)
Figure 20: Traction motor controller
2.3.3 Armature balancing
2.3.3.1 AN UNBALANCED ROTOR
Unbalance exists in a rotor when the mass center axis is different to its running center axis.
Practically all newly machined parts are non-symmetrical due to blow holes in castings, uneven
number and position of bolt holes, parts fitted off-center, machined diameters eccentric to the
bearing locations etc.

33. 23
An unbalanced rotor, when rotating, wants to revolve around its mass center axis. Because the
bearings restrict this movement, the centrifugal force, due to the unbalance, causes the rotor to
vibrate. This vibration causes wear to the bearings, creates unnecessary noise, and, in extreme
cases disintegration of the rotor itself can be experienced. It is therefore necessary to reduce
the unbalance to an acceptable limit
.
Figure 21: Armature balancing
2.3.3.2 BALANCING LIMITS
There are balance limits, just like machining limits, where the unbalance is acceptable.
International and national standards are quoted for rotors, for example: car wheels are balanced
to a limit of grade 40 and small electrical armatures are balanced to grade 2.5. The grades are
converted to unbalance units, depending on the rotational speed of the rotor as per ISO 1940
standards.
Use our balancing calculator: tolerance calculator

34. 24
2.3.3.3 UNITS OF UNBALANCE
The units of unbalance are mass times radius, for example: a weight added to a certain position
on the part being balanced would shift the mass axis into the running axis and therefore be in
balance. The weight of correction multiplied by the applied radius will give an unbalance unit.
For metric measurement the units will be gram-millimeters (gym) or for large rotors, gram-
centimeters. The Imperial equivalent will be gram-inches or ounce-inches. This weight (mass)
would be applied at a radius from the running center at the light position.
2.3.3.4 TYPES OF ROTORS
Rotors fall into two groups. One is where the rotor is rigid and does not deflect up to and
including the operating speed.
The other group comprises flexible rotors that “bow” up to the operating speed. The first
deflection seen is a “skipping rope effect” which means the center of the rotor at speed moves
out from its rotational axis, causing high “static” unbalance.
2.3.3.5 TYPES OF UNBALANCE
There are three types of unbalance:
1. Static unbalance – is where the mass axis is displaced only parallel to the shaft axis. The
unbalance is corrected only in one axial plane.
2. Couple unbalance – is where the mass axis intersects the running axis. For example: a disk
that has swash run-out with no static unbalance. The unbalance is usually corrected in two
planes
3. Dynamic unbalance – is where the mass axis is not coincidental with the rotational axis. This
unbalance is usually a combination of static and couple unbalance and is corrected in two
planes

35. 25
2.4 Traffic Control Systems
Figure 22:Traffic control room
The Centralized Traffic Control with Color Light Signaling was introduced to the Suburban
Section of Sri Lanka Railways in 1962 and this CTC Center too was set up in 1962. Originally
the system was based in Relays (RCTC). Then, the system underwent several technological
changes including Electronic CTC in 1985 and Computerized CTC in 2007. At present, there
are 06 train controller positions and the CTC center handles about 290 trains daily. It is
considered as the heart of the train operation of Sri Lanka.
Figure 23: Train tracking monitor

36. 26
Figure 24: Srilanka traffic map

37. 27
2.4.1 Interlocking system
In the early days of the railways, signalmen were responsible for ensuring any points (US:
switches) were set correctly before allowing a train to proceed. Mistakes were made which led
to accidents, sometimes with fatalities. The concept of the interlocking of points, signals, and
other appliances were introduced to improve safety. This prevents a signalman from operating
appliances in an unsafe sequence, such as setting a signal to 'clear' while one or more sets of
points in the route ahead of the signal are improperly set. Early interlocking systems used
mechanical devices both to operate the signaling appliances and to ensure their safe operation.
From about the 1930s, electrical relay interlocking’s were used. Since the late 1980s, new
interlocking systems have tended to be of the electronic variety. Interlocking’s can be
categorized as mechanical, electrical (electro-mechanical or relay-based), or
electronic/computer-based. All these interlocking’s are used in Sri Lanka at present, but the
mechanical interlocking systems are now being replaced by the other. They are explained
briefly below.
2.2.3.1. Mechanical interlocking
These types of system are not used in Sri Lanka railways. These are operated using
the lever frames. A typical picture of the lever frame is shown in figure below. lever frames are
used for the operation of interlock the signals and points to allow the safe operation of trains in
the area the signals control. Located in the signal box, the levers are operated by the signalman.
In mechanical interlocking plants, a locking bed is constructed, consisting of steel
bars forming a grid. The levers that operate switches, derails, signals or other appliances are
connected to the bars running in one direction. The bars are constructed so that if the function
controlled by a given lever conflicts with that controlled by another lever, mechanical
interference is set up in the cross locking between the two bars, in turn preventing the
conflicting lever movement from being made. The following figure shows the picture of a
locking bed used in Sri Lanka railways in past.

38. 28
Figure 25: Mechanical inter locking
In purely mechanical plants, the levers operate the field devices, such as signals, directly via
a mechanical rodding or wire connection. The levers are about shoulder height since they must
supply a mechanical advantage for the operator. Cross locking of levers was affected such that
19
2.4.1.1 ELECTRO-MECHANICAL INTERLOCKING
This type of interlocking system is called relay based interlocking system and it is used in
maradana yard heavily. From loco junction (Orugodawaththa) to Wadduwa, this relay based
(Electro-mechanical) interlocking system is used in Sri Lanka. Following picture was captured
at the relay house situated at the maradana yard during my visit to Sri Lanka railways.
Figure 26: Relay room

39. 29
The relay room consists of racks which are wired and on which the relays are mounted.
This is the interlocking Centre of the Station. This relay room on one side is connected to the
panel to receive commands from the panel for operation of the functions and also to give
indication to the panel to show the status of the functions which are controlled by the
interlocking. On theother side, this relay interlocking takes inputs from the field like position
of signals, points, track circuits, etc., and gives output to outdoor functions to drive them. These
interlocking’s used in maradana yard are electrically operated and is consist of complex
circuitry made up of relays in an arrangement of relay logic that ascertain the state or position
of each signal appliance. As appliances are operated, their change of position opens some
circuits that lock out other appliances that would conflict with the new position. Similarly,
other circuits are closed when the appliances they control become safe to operate. Equipment
used for railroad signaling tends to be expensive because of its specialized nature and fail-safe
design.
These interlocking’s which are operated solely by electrical circuitry can be operated locally
or remotely, with the large mechanical levers of previous systems being replaced by buttons,
switches or toggles on a panel or video interface. These types of interlocking may also be
designed to operate without a human operator
2.2.3.3. Electronic interlocking
This system is the modern interlocking system used in Sri Lanka railways and is
used for stations controlled from waadduwa to Galle. These interlocking systems used in Sri
Lanka are solid state, where the wired networks of relays are replaced by software logic running
on special-purpose control hardware. The fact that the logic is implemented by software rather
than hard-wired circuitry greatly facilitates the ability to make modifications when needed by
reprogramming rather than rewiring. In Sri Lanka railways, VPI interlocking is used. And
following is a block diagram which depicts the connection of point machines and the signal
lights to the VPI interface interlocking.

40. 30
Figure 27: Electronic control interlocking system
Solid State Interlocking (basically the Electronic Interlocking) is a data-driven signal control
system designed for use throughout the British railway system. SSI is a replacement for
electromechanical interlocking which are based on highly reliable relay technology and has
housing but the same functionality can be achieved with a relatively small number of
interconnected solid state elements as long as they are individually sufficiently reliable. SSI
has been designed to be compatible with current signaling practice and principles
ofinterlocking design, and to maintain the operator's perception of the behavior and appearance
of the control system. The operating principle of the Solid-state interlocking system (SSI) is
given in Appendix 1.
2.4.2 Wayside Signalling Equipment
Each circuit detects a defined section of track, such as a block. These sections respirated
insulated joints, usually in both rails. To prevent one circuit from falsely powering another in
the event of insulation failure, the electrical polarity is usually reversed from section. Circuits
are powered at low voltages (1.5 to 12 V DC) to protect against line power failures. The relays
and the power supply are attached to opposite ends of the section to prevent broken rails from
electrically isolating part of the track from the circuit. A series resistor limit current when the
track circuit is short-circuited. In some railway electrification schemes, one or both of the
running rails are used to carry the return current. This prevents use of the basic DC track circuit
because the substantial traction currents overwhelm the very small track circuit currents.
Where DC traction is used on the running line or on tracks in close proximity then DC track

41. 31
circuits cannot be used, similarly if 50 Hz AC electrification is used then 50 Hz AC track
circuits cannot be used.
To accommodate this, AC track circuits use alternating current signals instead of direct current
(DC) but typically, the AC frequency is in the range of audio frequencies, from 91 Hz up to 10
kHz. The relays are arranged to detect the selected frequency and to ignore DC and AC traction
frequency signals. Again, failsafe principles dictate that the relay interprets the presence of the
signal as unoccupied track, whereas a lack of a signal indicates the presence of a train. The AC
signal can be coded and locomotives equipped with inductive pickups to create a cab signaling
system.
2.4.3 Track switching (Point Machines)
In SLR, they used electrical point machines in order to switch the track and a
picture of the track switching machine in maradana yard is shown in figure 5 below. Electric
Point Machine is an electrically driven machine used for the operation of points in
Railway yards and comprises of an electric motor, point mechanism and circuit control device.
Figure 28: Track changer
This point machine consists of a DC series motor, friction clutch, reduction gears. Cams and
bars used for converting the rotary movement to linear movement. For the operation of switch
and lock the main gear wheel in the mechanism revolves less than one revolution. The type of
motor used in point machine is a D.C. series motor; since its initial starting torque is high. The
operating voltage of point machine motor is 110VDC at 3Amps current. Simply these point

42. 32
machines convert the rotational motion of the motor into linear motion required to switch the
points. Since it consists of gears, gear assembly also provides required transmission ratio so
that it can generate necessary force to move switch blades. They perform following function,
 Opening of the detection contacts.
 Unlocking of point
 Operation of point from ‘N’ to ‘R’ or ‘R’ to ‘N’
 Locking of the point
 Closing of detection contact.
Generally, we can brief the operation of point machines further as
follows,Following is the picture of the motor and the gear system of a point machine used in
SLR.Following picture shows the structure of the track and how the point machine is attached
to the track in order to switch the track. Inhere I have labelled the rods and other major parts.
As shown in figure 6 above, the motor consists of three terminals where middle terminal
iscommon and the other two terminals are used for the forward and reverse operation of
motor.As shown in figure 6, there is a contact block and I have named it as Left (L) and Right
(R) asin figure 6, I have also named the movable contact with the rod as Y. this contact block
is Movable Contact with the rod (say Y)
Figure 29: Way side signal
actually, used for a safety purpose in order for the controller to know whether the track is switch
properly or not. Normally when the track is switched to one direction, using the detection rod

43. 33
this will allow the contact inside the contact block to go and contact with another contact which
are named as L and R in figure. L and R represents left and right contacts (fixed) respectively.
When Y contacts with R, a signal ,
will never glow Green for the drivers and therefore the train will have to be stopped. As you
can see from the figure 6 above, there is a reed switch and this is for safety. This is because in
case of breakdown of point machine, when the technicians are at the job, in order to let the
controller at the centralized station know that the technicians are still at work, this switch is
used. Once the lid of the point machine is closed, this switch will get activated and thereby the
controller knew that the work is complete. If the lid is open, then the switch gets normally open
and then the controller knew that the work under going.
2.4.4 VHF/UHF Radio Network & Optical Fibre Communication System
In 1980, SLR planned and implemented it in 1983 to modernize the train control telephone
system. Following the other modem railways, SLR implemented the island wide Radio-
Communication Project, UHF/VHF multi-channel analogue system for train controlling doing
away with the overhead wire omnibus telephone system. Although it was only for voice
communications, at that time it was considered a very big leap forward implemented by making
use of some of the SLT infrastructure (repeater station towers, emergency power supplies etc.),
which helped float the project economically. Now the voice communication radio system is
defunct, outdated and could not be maintained in good order due to lack of spare parts from the
OEM Company — ABB of Switzerland from 1993). Today, SLR is at the cross roads like so
many other railways were in the past, and has to decide which type of communication
modernization it should undertake to avoid failures and assure the safety of the commuters,
goods, running staff and infrastructure. Taking into consideration the experience of other
railways worldwide, SLR is proposing to lay a Fiber Optic Cable (FOC) alongside the railway
tracks as the backbone network of a new digital integrated telecommunication system with a
mobile communication system exclusively for the SLR train communications from the railway
stations and the train control offices. SLR is planning to lease out the extra fibers of the FOC
to other service providers such government institutions.

44. 34
Figure 30: signal communication system
The three UIC experts were Mr. Klaus Konrad, Chairman of the UIC GSM-R (Global System
for Mobile Communication — Railway) project and leader of the railway group, Mr. Hans
Bier, Telecom expert and former Chairman, GSM—R project in Germany and Mr. Peter Hans
Fischer, Chairman GSM-R project in Austria. Their opinions and recommendations were that
SLR should deploy the well proven GSM-R technology for the railway mobile communications
system. They categorically said that the GSM-R technology was well advanced and had been
implemented in most modem railways well over a decade showing the expected stability to be
the bearer of the railway mobile communication needs.
Their presentations gave the information about the specifications and standards for GSM-R,
actual position it has gained with the modem railways in Europe and worldwide due to the very
attractive features and fast responses required for the railway communications. They also
provided information about the available technologies like CDMA and compared them with
GSM-R.
Mr. Konrad stated that GSM-R follows the main stream of GSM and was therefore an upto
date technology which was flexible and stable. It has been deployed as way back as 1994 with
the railways and proved to be very efficient. It covers the railway needs and is a bearer service
for actual and future applications. It is now an accepted worldwide phenomenon with the
mobile railway communications.
Mr. Fischer stated that GSM-R could be implemented in stages according to the requirements
of the railways as it was a modular system. The full range of railway features can only be

45. 35
provided within a GSM-R network, although public GSM operators could allow a railway to
build a virtual private network and to start with some basic functionality.
Mr. Bier gave a lengthy explanation regarding the differences between GSM-R and CDMA
systems. He concluded that even if CDMA developed the full functions, they would not be
available, tested and validated within the next decade.
He categorically stated that at present there was no railway which had yet approved such
functionality with a CDMA system. He reiterated that the Railway Communications was far
different from the Public Telecommunications, as it was a speciality which should assure the
safety of the train loads of commuters, train running staff, freight and the infrastructure of the
railway.
In Sri Lanka, TRC is giving license to CDMA technology for the land telephones and GSM
technology for the mobile phones. In due course TRC will have to consider giving license to
SLR for the GSM-R technology.
Logically if over one hundred or more domestic/commercial telephones are out of order, there
will not be any danger to life and limb until they are put right even in few days time. But if a
section of the railway communication system or a telephone of a railway station is out of order,
it could bring disastrous results, like head on collisions of trains derailments, etc bringing
danger to the life of the train travelling public, running staff, freogjt and the infrastructure of
the railway. For example, if SLR had the new Communication system along the Coast Line
commissioned and in good working order before 26th December 2004., the Worlds’ worst train
disaster which killed over 1300 commuters at Peraliya could have been averted. Due to the
safety aspects of the system an accepted dedicated frequency bands for the GSM-R system
have been exclusively reserved in the frequency bands spectrum for the railway
communications internationally. This will avoid any interference from other users of the
communication systems at large in the Island. The primary function of the railway
telecommunications has been and will continue to be, to support the safe working of trains, the
signalling or train control function. The communications network also supports other train
operations, business applications in freight and passenger markets, safety response and
security. As the present analogue communication system is defunct and no original, spare parts
are available to maintain it., the proposed new Digital Integrated Telecommunication System

46. 36
for the SLR should be implemented as early as possible for the safety of the train travelling
public, freight, running staff of the trains and the infrastructure of the railway.
Figure 31: Fibre optic communication system
The new FOC backbone network will pave the path to make money by the SLR by leasing out
the extra fibers as adopted by number of railways worldwide by commercializing the venture.
SLR could have number of case studies on this as some railways are making more money out
of their communications network, than by selling the train ride tickets and carrying freight. The
experience of those railways show that the project cost could be covered up in few years time
giving more independence to utilize the accrued funds in due course for the other railway
improvements without depending from the Treasury coffers annually. The long felt
modernisation plans of SLR could be undertaken in stages to par with the other modem
railways and to bring back the glorious past it had in the post independence era for clean
passenger carriages, to maintain punctuality of trains, to introduce more express intercity
named trains it had and to improve the safety of the trains.
2.5 Bench Fitting and Machining
I spend 3rd
and 4th
weeks in this work shop. In here do lot of machining process to components
of locomotives, machineries carriages and etc. There were lot of lathe machines, drilling
machines, shaping machines boring machines and etc. In this shop also repaired damper of
locomotive and locomotive couplings.

47. 37
2.5.1 Lathe Machines
Lathe machine is used for remove metal from the work-piece to required shape and size
by turning. Lathes are primarily used to manufacture circular parts, to lathe cylindrical surfaces.
To drill openings and to cut threads (inner and outer). The material should be harder than work
piece. The tool may be given any linear motion in any direction. In the workshop there are
center lathe machine and turret lathe machine
2.5.1.1 WORKING PRINCIPAL OF LATHE MACHINE
There are two ends, one end gets revolving for work-piece (live end). Other end not
revolving work-piece (dead end). the work-piece is revolving around its axis and cutting tool
feed into the work-piece or along the work-piece. Tool is linearly move.
2.5.1.2 MAIN PARTS OF THE LATHE MACHINE
 Headstock
The headstock is suited at the left hand end of the lathe machine bed. It supports the spindle
and driving arrangements. A separate speed changing gearbox is placed in the headstock.
The chuck is fixed right hand side of the headstock.
Figure 33: Turret Lathe Figure 32: Center Lathe
Figure 34: Headstock

48. 38
 Tailstock
Tailstock is used for support the work-piece at right hand side. In center lathe machine
tailstock can be moved only right hand or left hand side. But in turret lathe also it can rotate
itself. By holding the tool for tailstock. Can do drilling and boring processes. Turret lathe
machine can hold several tools by tailstock. When we needed other tool we can rotate turret
and do the process.
 Tool Post
The tool post is for the hold the cutting tool there are two types of tool post in the SLR.
Single tool post and four-way tool post. Single tool post can only hold one tool. But four-
way tool post can hold four tool. when we needed we can rotate, fixed it and use it.
 Chuck of the Lathe Machine
Lathe chucks are used for the rotating work-piece while it is holding. In SLR two types of
lathe chuck can see. There are three jaw chuck and, four jaw chuck. In three jaw chuck all
Figure 35/; Headstock
Figure 36: Tailstock
Figure 38: One Way Tool Post Figure 37: Four Way Tool Post

49. 39
jaws can adjust simultaneously. We can only hold a shaft concentrically shaft center and
chuck center. In four jaw chuck jaw can adjust independently so we can hold a shaft it
center eccentric from chuck’s center.
2.5.2 Shaping Machine
Shaping machine is use for machine flat surface on a horizontal, vertical or angular
plane in the shaping machine cutting tool and work-piece both are moving. By shaping machine
surface finishing and slot making are done.
Figure 41: 4 Jaw Chuck
Figure 40: 3 Jaw Chuck Figure 39: 4 Jaw Chuck

50. 40
2.5.3 Planning Machine
It is design for producing flat surfaces on a work-piece. It has stationary housing for the
holding the tool. There is a bed for work-piece holding. The bed moves reciprocating. The
work is moved against the tool. Because of its large size planer is capable of handling large
work-piece easily.
2.5.4 Drilling Machines
There are different types of drilling machine. These are used for to produce accurate
holes on work-piece. Radial arm drills, table drilling machine we can see in this work shop.
Figure 42: Planning Machine
Figure 43: Radial Arm Drill

51. 41
2.6 Tool Room
In this work shop cutting tools making, heat treatment processes, gear wheel cutting
etc. are doing. I spend 5th
and 6th
week in here.
2.6.1 Cutting Tool Making
In this workshop tool are making from High Speed Steel (HSS). HSS bars receiving from
Blacksmith workshop. A small piece of HSS is joint to a mild steel bar. The small piece of HSS
is the cutting tool. Mild steel part is holding part. It is fitted to the machines tool post
2.6.1.1 GRINDING
In this workshop first HSS piece that joint to mild steel is grinding by grinding machine
to certain back rake angle, front clearance angle, end cutting edge angle, side cutting edge
angle, side rake angle and side clearance angle.
Piece of HSS Piece of mild steel
Back rake angle
Front clearance angle
Figure 44: Cutting Tool
Figure 45: Side View of a Tool

52. 42
2.6.1.2 HEAT TREATMENT
To metal cutting process metal to be very hard. By heat treatment process we can hard
the metal. In this tool room heat treatment processes are done. Sometimes HSS and mild steel
are proceeded. For HSS first heating up to the 12000
C. After its cooling down by compressed
air blowing. HSS can be cooling down by air, oil, water. Maximum strength we can get by
cooling down by air, Minimum strength we can get by cooling down by water. For mild steel
first heating up to 9000
and after it is cooled by oil, It maximum strength can get by cooling
down by oil. Minimum strength can get by cooling down of air.
Heat treatment processes are not only for the hardening the material. Some metals can
get soften. Cupper heating up to the 3400
C and cooling by water.We can get soften cupper by
this process
End cutting edge angle
Side cutting edge angle
Side rake angle
Side clearance angle
Figure 46: Top View of a Tool
Figure 47: End View of a Tool

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2.6.2 Gear Wheel Cutting
2.6.2.1 SPUR GEAR
For gear wheel cutting use the milling machine horizontal vertical both can use for gear
wheel cutting. In this shop has British standard for gear cutting.
Example if we need 16 teeth spur gear wheel.
40
16
=2 and extra is 8
So we have to find relevant whole circle of universal index head. After a cut a one teeth then
after we have to rotate 2 rounds and 8 whole of index head then we can cut next teeth. Like this
we can cut spur gear wheel.
Figure 48:Figure 2.23- Furnaces
Figure 50:Divide Head Figure 49: Milling Machine

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2.6.2.2 BEVEL GEAR
For cutting bevel gears. Universal index head has to rotate to a certain angle
horizontally or vertically. This angle is changed by the gear wheel. Then can use same method
for use to spur wheel cutting.
2.6.3 Profile Tool
Profile cutting tool is making for the cut special shapes quickly. Sometimes this shape
can’t cut by normal cutting tools. In SLR using profile cutting tool for cutting steel wheels of
railway.
2.6.4 Engraving Machine
There is a one engraving machine in this shop. It is for the engraving letters on the metal
parts. It’s one end we can guide to a shape that we want and other end engrave the shape on
the work-piece. By adjusting this machine, we can enlarge or reduce the size of engraving.
Figure 51: Profile Tool
Figure 52: Engraving Machine

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2.7 Diesel Electric Locomotive Repair (4 stroke)
In this workshop 4 stroke diesel engines were servicing and repaired. I spend 14th
, 15th
,
and 16th
week in this shop. Class M4, M5, M8, M9, and M10 locomotive are the two stroke
locomotive engines. All parts of locomotive are disassembled and some part send to other shops
for repair.M4, M5, M8, M9 locomotive has V12 engines. Some of M8, and all M10 locomotive
have V16 engines.
2.7.1 Working Principle of 4 Stroke Diesel Engine
In this engine 4 valve on the engine head. 2 for exhaust and 2 for intake the air. Air is
taking by the when piston going to BDC from TDC. From intake 2 valve. Then compressed.
Diesel inject to the compressed (also heated) air. Then piston go to BDC by power stroke.
When go to the BDC. And When come to the TDC. Exhaust valve was opened. Then exit the
exhaust air.
2.7.2 Piston Rings
Piston rings are split rings that placed on piston’s groove. Piston rings do valuable
functions in engine. Sealing the air of combustion chamber between combustion chamber and
crank case. Regulating engine oil consumption by scraping oil from the cylinder walls back to
the sump. In normally locomotive piston has 5 rings. For air compression dedicated 3 rings.
For oil scraping dedicated 2 rings. When piston rings install to the piston the space of rings
must be avoided place in on to on. In oil scrapping rings has some holes for distribute oils for
cylinder wall from piston. Oil came from through piston connecting rod to from crank shaft
Oil rings
Compression rings
Figure 53: Piston Rings

56. 46
2.7.3 Sleeves of 4 Stroke Engine
There is special part in engine block. It is called sleeve. Sleeves can be used for cooling
cylinder when circulating the water around sleeve. After long running of engine. Piston and
sleeve get weird. So piston can have replaced that next size of used piston. When installing
new piston. Sleeve must be machined. This process is called engine boring. When sleeve almost
machined. Sleeve can be replaced. Sleeve manufactured by strength material more than engine
block. Sleeve is fitted to the engine block by tight fit. With advantages of taper in sleeve and
taper hole of engine block.
2.7.4 Generator Alignment for the Crankshaft
Main generator is directly connecting to the engine crankshaft. It is rigid coupling
between main generator and crankshaft. It is very important to there is no any misalignment in
generator and crankshaft. When coupling the generator. At first they coupling the generator to
the fly wheel. There is a window to the see to crankshaft in engine block. Then opened it nearest
one to generator. After put a dial gauge to between counter weight of crankshaft. At first rotate
the crankshaft a round. We can see when rotating first time crankshaft. Dial gauge show some
readings It is reading not constant. Reading is changing when rotating. After put thin metal
sheets to tighten position in generator. It is do until dial gauge reading show constant reading
all over the 360 degrees. If this process not properly done. Crankshaft can be deforming.
Figure 54: M8 Engine Sleeves

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2.7.5 Crankshaft Installation.
When crankshaft installing to the engine block we have to install bearing first. This
bearing are journal bearings. Bearing should be checked its surface before install the engine
block. Surface is checked by bedding bar. It is blue led smeared bar. It is place on the journal
bearings part and rolling. After some areas not touch with blue led. So then are that touch with
led have to scrape by metal scraper and for smooth scraping for sand paper (about 360). So this
bearing has grooves and hole for flow lubricating. Oil is coming from holes of crankshaft.
Journal bearing have two parts upper part and down part. Fist down part have to place correctly
after installed the crank shaft. Then installed the upper part. After installed the crankshaft
bearing caps. When tightening the bolt of bearing caps. Manufactures given torque have to
consider.
2.8 Diesel Engine Auxiliaries
Mainly expressors, radiators, intercoolers, turbochargers, pumps, and other auxiliary
drivers were repaired
2.8.1 Air Compressors, Exhauster and Expressor
2.8.1.1 AIR COMPRESSORS
Air compressors of locomotives. Almost two stage compressors One is law pressure
compressor. Other is high pressure compressor. Thera are few advantages of two stage
compressor over single stage compressor.
 Gas can be compressed to sufficient high pressure
 Pressure ratio of each stage lower. So air leakage is lower
 Low pressure ratio in cylinder improve the volumetric efficiency
Figure 55: Bedding Bar

58. 48
Suction air enter to low stage cylinder to wire mesh filter. This is use for air brakes and
horn.
2.8.1.2 EXHAUSTER
Exhauster is the inverse process of the air compressor. It is makes a vacuum. It is used
for vacuum brakes.
2.8.1.3 EXPRESSORS
Expressors is a device that combination of air compressor and exhauster. This used for
air brakes of engine and vacuum brake of rail carriage
.
Figure 56: Air Compressor
Figure 57: Expresser

59. 49
2.8.2 Radiators and Intercoolers
In radiators and intercoolers iron or cupper tubes to heat exchange. These tube can be
damaged or blocked. First these are separate to parts and cleaned. After Kerosene and caustic
soda used to clean the radiators. But not intercooler clean with intercoolers. Because
intercoolers made with cupper tube cupper tube can’t resist again caustic soda. Secondly this
component sunk in to water and connected to the pressurized air. If there is any leakage in tube.
Can be identifying that when bubbling.
2.8.2.1 RADIATORS
Radiators is main components of engine cooling system. Radiators are used for cooling
the water that circulating the through the engine and other components. In radiator maximize
surface area of water for transfer the heat for atmosphere. In locomotive has 6-8 radiators for
cooling huge amount of water.
2.8.2.2 INTERCOOLERS
In this locos intercooler use for cool to air. There are intercooler in compressors and
turbocharger. In ideal intercoolers n pressure change it cooling down to intake temperature of
air
Figure 58: Radiator

60. 50
2.8.3 Turbochargers and superchargers
2.8.3.1 TURBOCHARGER
Turbochargers contain two main parts. Impeller and turbine. Turbocharger are used for
four stroke engine to breathe more air into the combustion chamber using exhaust power. The
turbine of turbo driven by power of exhaust gas exhaust. Impeller and turbine mounted to the
one shaft. So impeller also rotating. Then impeller supply more compressed air to the
combustion chamber.
2.8.3.2 SUPERCHARGERS
Superchargers used in to two stroke engine. Superchargers duty is similar to the
turbochargers. But supercharger is driven by crankshaft power. But turbocharger of locomotive
are centrifugal type. But superchargers of locomotive are twin root type. So this s also called
as root blowers
Figure 60: -Turbocharger
Figure 59: Turbocharger

61. 51
2.9 Diesel Hydraulic Locomotive Repair
In this workshops S class, W class, Y class are repaired in this workshop. S class trains
are power sets. W class trains power are transmitted to bogie through torque converter. Also Y
class. S class trains transmit power as normal locomotives.
2.9.1 Power Transmitting Through Torque Converter
In W and Y class engine first coupling to a torque converter then. Torque converter
connect to a shaft. The shaft joined to the gear box that have only reverse and forward gear.
2.9.2 Torque Converter
Torque converter is a fluid coupling method. Torque converter has the ability of
multiple the torque. Also torque converter has turbine and impeller. Impeller connect to the
crankshaft. Then fluid goes to turbine. Then turbine is driven. In locomotives diesel are used
as the fluid. In these locomotives torque converter fluid pressure should be 60Psi-80Psi. Before
coupling the impeller to the crankshaft. There is a clutch.
Figure 62:Torque Converter Figure 61:-Turbine of Torque Converter

62. 52
2.9.3 Timing of Engine
Ignition timing is very important. Because if timing is not perfectly. It is problem for
engine efficiency. Also can be propagating the engine. For engine timing we have to first install
crankshaft, fly wheel, camshafts, injector pump, timing wheel, idling wheel and etc. Frist all
wheel set the according to the its marks, then a piston (that piston called by engine manufacture)
get the TDC by rotate crankshaft. Then put the dial gauge to the piston and after piston go back
to the little bit while watching the dial gauge reading. Then consider about injector pump. After
a dial gauge put to the relevant plunger after removing of delivery valve. So plunger get up to
the some certain readings of the dial gauge. After crankshaft and injector pump coupling via
gears. Then after piston that mentioned above positioned to the its previous dial gauge reading.
Then check the dial gauge that measured of plunger’s stroke reading is match with its previous
reading. If it is not. We have to do it again. Certain dial gauge values are given by engine
manufacturer. Some timing process have to do several times. Engine timing process different
according to the engine. I explained above S9 locomotive’s German MTU engine timing
process.
S10, S11, S12 locomotive engine has electronic timing process. Fuel injecting
controlled by ECU (Engine control unit). This system also called common rail.
2.9.4 Wheel and Underframe
In this workshop engine locomotives bogies were repairing and servicing, 22nd
and 23rd
weeks of my training period were appointed to this workshop.
2.9.5 What is Bogie
Bogie in locomotive is essential part of the train. its drive system and its guidance
mechanism. Normally locomotive has two bogies. Generally, it is located on two ends of
locomotives. Almost locomotive’s bogie has 6 wheels. Sometimes it has 4 wheels. The wheels
guide it along the track. It gives cushioning against the shocks transmitted from the track during
motion. Bogie has 2 DC motors (also called as traction motors).. DC motors driven by
electricity that generate by main generator.

63. 53
2.9.5.1 HOW BOGIE IS CONNECTED TO THE ENGINE COMPARTMENT
Bogie must be connected to the engine correctly. Every bogie is connected to the engine
compartment by four dampers and bogie center. In class M locomotive bogie’s bogie center
has pit. Connect to the engine compartment with like short shaft thing. So it is on the bogie
center with oil layer. But in S classes’ bogie center is like a pin. It is install in to the engine
compartment.
Figure 63: DC Motors on Bogie
Figure 65: Completed M4 Bogie
Figure 64: M10 Bogie Center
Figure 66: Brake Hangers

64. 54
2.9.6 Brake Hoses
Locomotive brakes are run with air. Vacuum or air brake. Power sets (S class) has air
brake. Other almost locomotive has vacuum brakes. Vacuum brakes are fail safety. Vacuum
brakes are quicker than hydraulic brakes. In this Workshop all components of brake system
(brake hangers, brake shoes, brake hose and etc.) are installed. In air brake big advantage is its
cylinder is smaller than vacuum cylinder.
2.10 Inspection
Staff of this workshop are working in everywhere in workshops. Duties of this
workshop are examine the repaired, serviced components and ordering the new components to
procurement section. That ordering forms called supplementary indents forms (SI forms).
Almost staff of this workshop are examiners. They measured lot of critical parts that
manufactured in SLR or repaired parts. They measure crankshafts, piston rods, pistons,
bearings and lot of components of engines. They use Vernier calipers, micrometers, depth
gauges and lot of gauges for measuring. My last week of the training schedule deploy to
familiarization with above processes.

65. 55
3 Conclusion
Having my internship in Sri Lanka Railways was great opportunity in my life. This is
my second time of industrial experience. Sri Lanka Railways was comprised with equipment
which are not available in anywhere in Sri Lanka. Locomotives, power sets, machines and
signal system in there.
I was appointed to lot of workshops in Sri Lanka Railways. I was able to experience
with diesel electrical loco repair workshops. I got lot of practical experience about various kind
of engine. After I trained in electronic controls, DC electrical machines & rewinding work shop
I got lot of experience about processes. Unimaginable gathered of machines. Some machines
only exist Sri Lanka Railways in Sri Lanka.
After I was appointed to Bench Fitting & Machining workshop. It was very good
experience in my training period. It was tool room. In tool I familiarization tool making. Tool
making, heat treatment and etc. then I was appointed to training in Traffic Control Systems, in
Dematagoda. So, I get knowledge about Interlocking System and Wayside Signal Equipment.
VHF/UHF Radio Network, Optical Fiber Communication System are learnt. Also, it was a new
experience. After I did my training at Maradana LTL unit. There are lot of controlling processes
use in SCADA System.
I moved to two stroke locomotive repairing workshop. In this workshop two stroke
locomotives were repaired and servicing. Lot of locomotives has under this workshop. So, I
familiarization with engine repairing and servicing. And know about lot of components that
include only in locomotives. After I moved to workshop that almost similar to previous
workshop. In this workshop repaired and servicing only four stroke locomotives. I get lot of
experienced in this workshop.
Then I assign to diesel auxiliary repair workshop. Auxiliary driven devices such as
expressers, turbochargers etc. were repaired. Also radiators, intercooler, etc. all cooling devices
were repaired and servicing here. Some components I never seen heard before. Expresser is
strange thing to me.

66. 56
After I appointed workshop that were repairing power set, Y, W class. So I
familiarization with power set engines and different transmission system in Y and W classes.
. I am very happy about to learn about it. Finally, I assign to work with inspection staff.
I work with inspection team. Learn How locomotive engine maintenance for about 50-60 years.
I spend my training period with different working environment. I worked with not only
engineers but also foreman, supervisors, technicians and labors. I was good opportunity as we
should also develop our ability to work with people in different levels in our carrier. And learn
how work with responsibilities of government section. It was very different from private
organization. When we work in government section we have to deal with public money. It was
huge responsibility.
I am very happy about training establishment. Staff treated me as an employee there.
Engineers and all other staff member are very friendly and give to me good support.
At first, I was quite nervous with working in professional environment because as this
my second industrial experience. Hence, I took some time to get ready to this environment. My
interpersonal skills were not good at all at beginning. Also, I hadn’t any experience work with
chief staff. So, I was mange to learn work with chief staff (Chief mechanical engineer, Deputy
mechanical engineer). And it was challenge to me work with staff in workshop. Because they
are in different levels. I have to learn how deal with them. I never had idea about responsibilities
in government section.
University of Vocational Technology Department of Electrical & Electronic
Engineering and National Apprentice and Industrial Training Authority (NAITA) together are
doing an appreciative work on arranging this industrial training to Engineering undergraduates
to get exposure in the industry. It is very important to get the exposure from industry before
someone get into it. It is very important to choose their field in final year.

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My suggestion for the industrial training is to let undergraduates to work in at two
training establishment which would let them learn more in different fields before selecting final
year stream
Finally, this industrial training program is beneficial for an undergraduate’s
professional skills and attitudes. This period assists undergraduates to understand the role of
an engineer in the industry and also become one of them.