Brief History Dlw

STUDY ON DIESEL LOCOMOTIVE WORKS

TRANING REPORT

SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING

HARYANA COLLEGE OF TECHNOLOGY AND MANAGEMENT

AMBALA ROAD KAITHAL

AS PART OF COURSE OF

B.TECH. ( MECHANICAL ENGINEERING)

KURUKSHETRA UNIVERSITY

KURUKSHETRA

SUBMITTED BY

Gaurav kumar Bohria

ROLL NO. 1709644

PREFACE

The globe is shrinking .The world is taken over by the technicians.A day after day a new technology srises. A technician without practical knowledge is zero,don’t matter how many books you have studied .practical know how is must to be successful.

Industrial trainning is the bridge for a student that takes him from the world of the theoretical knowledge to that of practicle one.

> training is a good industry is highly conductive for:

1. development of solid foundation of knowledge and personality.

2. confidence building.

3. Pursuit of excellence and disipline.

4. enhancement of creativity through motivation and drive which help produce professional and well for the rigorous of the job.

During the training I got the exposure to various eqipment 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

enviroment.

This traininig at the “DIESEL LOCOMOTIVE WORKS VARANSI”

STUDENT ‘S DECLARATION

I hereby certify that the works which is being done in the project entitled “study on diesel locomotive by GAURAV KUMAR

BOHRIA as per course requirement of b.tech.

Submitted in the department of Mechanical Engineering at HARYANA COLLEGE OF TECHNOLOGY AND MANAGE

MENT under KURUKSHETRA UNIVERSITY ,KURUKSHETRA is recorded of my own work

carried out during a period .

The presented in this project has not been submitted be me in any other institute for the award of b.tech degree.

Signature of HOD.

ACKNOWLEDGEMENT

I highly grateful to the D.P GUPTA(Director), HARYANA COLLEGE OF TECHNOLOGY OF MANAGEMENT,for providing this opportunity to out the project work.

The constant guidence and enncourge ment received from the department of mechanical,HCTM ,KAITHAL has been of great help in carrying out project and is acknowledge with reverential thanks.

I would like to express a deep sense of grantitude and thanks to HOD ER. R.P SINGH who help in the project work.without the wise counsel and able guindance ,it would have been quite difficult to complete the project work in this manner.

We express gratitude to other faculity members of the department of mechanical engineering ,HCTM for their intellectual support throughtout the couse of this work.

INTRODUCTION TO DLW

Background – diesel locomotive works (DLW) is production unit

under the ministry of railways. This was setup in collaboration with

American locomotive company (ALCO) USA in 1961 and the first

locomotive was rolled out in 1964. This unit produces diesel electronic

locomotives and DG sets for Indian railways and other customers in India

and Abroad.

Subsequently a contract for transfer of technology of 4000 HP

Microprocessor Controlled AC/AC Freight (GT 46 MAC) / passenger

(GT 46 PAC) locomotives and family of 710 engines has been signed

with electro motive division of general motors of USA for manufacture

in DLW. the production of these locomotives has now started and thus

DLW is the only manufacturers of Diesel Electric Locomotives with both

ALCO and General motors technologies in the world.

Brief History

Set up in 1961 as a green-field project in technical collaboration with

ALCO/USA to Manufacture Diesel Electric Locomotives.

First locomotive rolled out and dedicated to nation in January,1964.

Transfer-of-Technology agreement signed with General Motors/ USA

in October,95 to manufacture state-of-the-art high traction AC-AC

diesel locomotives.

A flagship company of Indian Railways offering complete range of

flanking products in its area of operation.

State-of-the art Design and Manufacturing facility to manufacture

more than 150 locomotives per annum with wide range of related

products viz. components and sub-assemblies.

Unbeatable trail-blazing track record in providing cost-effective, eco-

friendly and reliable solutions to ever-increasing transportation needs

for over three decades.

Fully geared to meet specific transportation needs by putting Price-

Value-Technology equation perfectly right.

A large base of delighted customers among many countries viz. Sri

Lanka, Malaysia, Vietnam, Bangladesh, Tanzania to name a few,

bearing testimony to product leadership in its category.

VISION:

To be a World class manufacturer of Diesel Electric locomotives."

QUALITY POLICY:

"We are Committed to Excellence in all Activities and Total Customer

Satisfaction through Continuous I improvement in Quality of Products

and Services."

SCOPE:

- "We shall achieve our vision through Continuous Improvement in

the areas of Product Quality, Research and Development, Supplier

Partnership, Human Resource Development and Team Work with

emphasis on Core Competence leading to Customer Satisfaction

and Business Excellence."

SALIENT FEATURES

Annual production capacity 125 Locomotives

Annual turn-over (Rs) 5000 million

Total number of staff 7223

Workshop land 89 Hectares

Township area 211 Hectares

Covered area in shops 86300 Sq.m

Covered area of other service buildings 73700 Sq.m

Electrical power requirement 3468 KVA

(Average maximum demand)

Electrical energy consumption (units/year) 19.8 million

Stand by power generation capacity 3000 KW

Locomotives — General Information:

Classification of Locos:

What do the designations such as 'WDM-2' mean?

Locos, except for older steam ones, have classification codes that identify

them. This code is of the form '[gauge][power][load][series][subtype]

[suffix]'

In this the first item, '[gauge]', is a single letter identifying the gauge the loco

runs on:

W = Broad Gauge

Y = Meter Gauge

Z = Narrow Gauge (2' 6")

N = Narrow Gauge (2')

The second item, '[power]', is one or two letters identifying the power

source:

D = Diesel

C = DC traction

A = AC traction

CA = Dual-power AC/DC traction

B = Battery electric(rare)

The third item, '[load]', is a single letter identifying the kind of load the loco

is normally used for:

M = Mixed Traffic

P = Passenger

G = Goods

S = Shunting

L = Light Duty (Light Passenger?) (no longer in use)

U = Multiple Unit (EMU / DEMU)

R = Railcar (see below)

The fourth item, '[series]', is a digit identifying the model of the loco. Until

recently, this series number was simply assigned chronologically as new

models of locos were introduced.

However, starting in 2002, for diesel passenger, goods, and mixed locos, i.e.,

WDP, WDG, and WDM sequences, (and only for them, apparently, not for

electrics, nor for diesel shunters), the series digit identifies the horsepower

range of the loco, with '3' for locos with over 3000hp but less than 4000hp,

'5' for locos over 5000hp but less than 6000hp, etc. This new scheme will be

applied to all passenger/goods/mixed-haul diesel locos starting in June 2002,

except for the WDM-2 and WDP-1 classes of locos.

The fifth item, '[subtype]', is an optional letter or number (or two of them)

that indicates some smaller variation in the basic model or series, perhaps

different motors, or a different manufacturer. With the new scheme for

classifying diesel locos (see above), the fifth item is a letter that further

refines the horsepower indication in 100hp increments: 'A' for 100hp, 'B' for

200hp, 'C' for 300hp, etc. So in this scheme, a WDM-3A refers to a 3100hp

loco, while a WDM-3F would be a 3600hp loco.

The last item, '[suffix]', is an optional indication that indicates something

special about the loco, such as a different gearing ratio or brake system than

usual.

So, a WCM-2 is a broad-gauge (W) DC electric (C) mixed traffic (M)

engine, model 2. Likewise, a WDS/5 is a broad-gauge diesel shunting

engine, model 5, and a ZDM-5 is a narrow-gauge diesel mixed-traffic model

5 loco. YAU-1 is the old series of MG EMUs run on the Madras-Tambaram

line.

The subtype indication of minor variations is not very systematic. Often

successive variants of a model are given subtypes 'A', 'B', etc. in alphabetic

order, e.g. ZDM-5A, WAM-4A, WAM-4B, etc., but not always. For many

loco classes (WDM-2A, WDP-2A, notably), the 'A' also indicates dual

braking systems (capable of hauling air-braked and vacuum-braked stock).

But in some, such as the WDM-2CA, the 'A' indicates a loco with only air-

brakes. A WAM-4R is a faster version ('R' for rapid?) of the WAM-4, and

WAM-4P is a version of the WAM-4 designed specifically for passenger use

('P'). But a WAM-4 6P is a version regeared and allowing all-parallel

operation of the traction motors. A WDM-2P is a prototype version of a

WDM-2 class.

Similiarly, a WAG-5HA is a WAG-5 with Hitachi motors ('H') built by

CLW; a WAG-5HB is the same, but built by BHEL. A WAG-5P,

interestingly, is a WAG-5 loco (a goods loco in its original design, as

indicated by the 'G') which has been modified by re-gearing to haul

passenger trains (the 'P' indicates 'passenger')! An 'E' suffix often indicates a

variant that is purely air-braked (WAP-1E, WAM-4E, etc., but redundant

with a WAP-4E.).

[5/02] As indicated above, a new system of classifying mainline diesels has

been introduced. The new scheme got off the ground with rebuilt WDM-2C

locos being reclassified as WDM-3A (as they have a power rating of

3100hp). It is likely that the new classifications will coexist with the old

ones for some time.

With the optional suffix, things get even less predictable and less systematic.

A WDM-2 5PD is a WDM-2 with a different gearing ratio (the '5P', usually

a 'P' in such a suffix indicates a gearing ratio suitable for passenger service).

On the other hand a WAM-4 6P indicates all 6 traction motors permanently

connected in parallel — in electric locos 'S' and 'P' often stand for 'series' and

'parallel' combinations of traction motors. Dual brake systems ('D'); similarly

with a WAM-4 6PD, another common designation. (It's been reported that

the 'PD' in these may actually refer to suitability for push-pull operation...??)

A WAP-1 FMII is a variant of the WAP-1 using Flexicoil Mark II bogies.

Ad hoc combinations of many such suffixes are possible, as with 'WAM-4 P

HS DB 6P' (HS = high speed, DB = dual-brake compatible, P = regeared for

passenger operations, 6P = all 6 traction motors may be placed in parallel

operation). The WAM-4 locos, in particular, are notorious for having

countless minor variations as CLW and various workshops keep making

minor experimental changes to them. Some sheds follow their own schemes

too. Bhusawal shed, for instance, adds 'DBC' or 'ABC' to loco classes to

indicate locos that have undergone conversion of the braking systems ('dual

brake converted', and 'air brake converted').

The model numbers are assigned chronologically as new loco types are

brought into use in IR, but there are some exceptions. Sometimes model

numbers are assigned to some experimental locos which are never brought

into regular use.

Some classification codes break the system above: e.g., 'RD' is used as a

code indicating the power and the load for diesel railcars, and not 'DR' as

one might expect: YRD-1 is a series of MG railcars, NRD-1 similarly an NG

series of railcars. Railcars used on the Tambaram line were classified simply

'RU'. 'RB' is used for railbuses, e.g., the WRB railbuses built on Ashok

Leyland bus frames operating between Bangarpet and Kolar.

PRODUCT OF DLW:

DLW is an integrated plant and its manufacturing facilities are flexible in

nature. these can be utilized for manufacture of different design of

locomotives of various gauges suiting costomer requirments and other

products. the product range avilable is as under. :

WDG4 4000 HP AC/AC Frieght traffic Locomotive

WDP4 4000 HPAC/AC Broad Gauge High Speed

Locomotive

WDG3D 3400 HP AC/AC Broad Gauge Mixed Traffic

Micro-Processor Controlled Locomotive.

WDM3C 3300 HP AC/DC Broad Broad Gauge Mixed

Traffic Locomotive.

WDM3A 3100 HP AC/DC Broad Gauge Mixed Traffic

Locomotive.

WDP3A 3100 HP AC/DC Broad Gauge High Speed

Passenger Locomotive.

WDG3A 3100 HP AC/DC Broad Gauge Freight

Locomotive.

WDM2 2600 HP AC/DC Broad Gauge Mixed Traffic

Locomotive.

WDP1 2300 HP AC/DC Broad Gauge Intercity Express

Locomotive.

WDM7 2150 HP DC/DC Broad Gauge Mixed Traffic

Locomotive.

WDM6 1350 HP DC/DC Broad Gauge Mixed Traffic

Locomotive.

WDS6 1350 HP AC/DC & DC/DC Broad Gauge

Shunting Locomotive.

YDM4 1350 HP AC/DC & DC/DC Broad Gauge Mixed

traffic Locomotive.

EXPORT LOCO 2300 HP AC/DC Meter Gauge/Cape gauge Mixed

Traffic Locomotive.

Diesel Generating Sets 800 KW to 2500 KW

Spare Parts fot engines, locomotives and generating sets.

WDG2 - WDG2 class 3100HP diesel electric locomotive with AC-DC

transmission, powered with DLW built 16Cyl. ALCO251C diesel engine, is

exclusively designed for heavy freight service. High adhesion two stage

suspension designed trucks minimise weight transfer and provide a higher

starting tractive effort and excellent riding quality. Ergonomically designed

cab is located between long and short hoods for either direction operation.

The load starting capability of locomotive is 4700 tonnes on steeper (1 in

300) gradient track. The locomotive is suitable for multiple unit operation

upto three units. WDG2 is popular for the low & easy maintenance at

extended periods, low rolling resistances, reduced noise & exhaust

emissions, fuel saving safe operation with anti-climber arrangement and

high hauling capability.

GENARAL CHARACTERISTIC:

Installed power 3100 HPPower input to traction under site condition - 550 C temp. & 600 M altitude

2750 HP

Gauge 1676 mmWheel arrangement Co-Co

Principal Dimensions

Height (Max) 4162 mm

Width (Max) 3016 mm

Length (Overall) 19132 mm

Locomotive weight basic 123000Kg.

Nominal axle load 20500 Kg.Wheel diameter basic 1092 mm.

Max. starting tractive effort 37884 Kg.Max. service speed 100 KmphFuel tank capacity 6000 Litres

WDM2 - WDM2 class 2600HP diesel electric locomotive with DC-DC

transmission, powered with DLW built 16 Cyl. ALCO251B diesel engine, is

designed for mixed traffic service, passenger or freight. The locomotive

equipped with fully equalized trimount trucks has medium axle loading and

higher adhesion. The versatile locomotive is geared for maximum speed 120

Kmph and suitable for multiple unit operation. WDM2 locomotive has

characteristics of low and easy maintenance, reduced noise & exhaust

emission, fuel saving, safe & comfortable riding quality and reliable high

performance.


Installed power 2400 HPPower input to traction under site conditions - 550 C temp. & 600M altitude

2250 HP

Gauge 1676 mmPrincipal Dimensions


Width (Max) 3010 mm


Locomotive weight basic 112800 Kg.Nominal axle load 18800 Kg.Wheel diameter basic 1092 mm.Max. starting tractive effort 30456 Kg.Max. service speed 120 KmphFuel tank capacity 5000 Litres

WDM2C

WDM2C class 3100 HP Diesel Electric Locomotive with AC-DC

transmission, powered with DLW built 16 Cyl. ALCO 251c fuel engine, is

designed for mixed traffic service with dual brake system, suitable for both

air and vaccume braked rolling stock. The cast steel fully equalized trimount

type trucks of locomotive minimise weight transfer and allow higher tractive

effort for moderate axle loading. The locomotive is geared for maximum

operating speed of 120 Kmph and has hauling capacity of above 4700 tonnes

at the speed of 60 Kmph. The riding quality is excellent. Full width cab is

located between short and long hoods for either direction operation. The

locomotive is provided with dynamic brake and is suitable for multiple unit

operation upto three units. Low and easy maintenance at extended periods,

low rolling resistance, fuel saving, reduced noise & exhaust emissions and

high reliability are the basic characteristics of the locomotive.Requisit safety

devices including anti climber arrangement are provided for safe operation

of locomotive.


Installed Power 3100 HP

Power Input to traction at site condition-55c temp and 600M altitude

2750 HP

Services Mixed Traffic

Guage 1676 mm

Wheel arrangement Co-Co

Principal Dimentions

Height (Max.)

Width (Max.)

Length (Overall)

4185 mm

3010 mm

17145 mm

Locomotive weight basic

118800 Kg.

Nominal Axle load 18800 Kg.

Wheel diameter basic 1092 mm

Max service speed 120 Kmph

Fuel tank capacity 5000 Liters.

WDP2 - WDP2 class 3100HP high speed dual cab diesel electric locomotive

with AC-DC transmission, powered with DLW built 16 Cyl. ALCO251C

diesel engine is exclusively designed for passenger service. Two stage

suspension flexicoil Co-Co MK-V trucks provide moderate adhesion and

excellent riding quality. Aerodynamic frontal profile and streamlined full

width body minimises air drag. Anti-collision posts are provided for

protection of crew and equipments. The locomotive is designed for speed

potential of 160 Kmph and is suitable for multiple unit operation upto three

units. WDP2 is popular for low and easy maintenance at extended periods,

reduced noise and exhaust emissions, fuel saving and safe operating

characteristics.


Installed power 3100 HP

Power input to traction under site conditions - 550 C. temp. & 600M

2750 HP

altitude

Gauge 1676 mm

Wheel arrangement Co-Co



Width (Max) 3124 mm


Locomotive weight basic 117000 Kg.

Nominal axle load 19500 Kg.

Wheel diameter basic 1092 mm.

Max. starting tractive effort 29250 Kg.

Max. service speed 160 Kmph

Fuel tank capacity 5000 Litres

WDS6 - WDS6 class 1350HP diesel electric locomotive with DC-DC

transmission, powered with DLW built 6 Cyl. ALCO251D diesel engine, is

specially designed for handling long and heavy train loads in Steel Plants

and Industrial Yards. The locomotive equipped with fully equalized trimount

trucks has high starting tractive effort and is capable of withstanding heavy

buffing loads of 400 tonnes. It is designed to negotiate sharp curves of 45

meter radius track and can work in multiple unit operation. A creep speed

control feature for operation between 1 to 7 Kmph can be provided as an

optional fitting.


Installed power 1350 HP

Power input to traction under site conditions - 550 C temp. & 600M altitude

1150 HP

Gauge 1676 mmPrincipal Dimensions


Width (Max) 3060 mm


Locomotive weight basic 126000 Kg.Nominal axle load 21000 Kg.Wheel diameter basic 1092 mm.Max. starting tractive effort 34020 Kg.Max. service speed 62.5 KmphFuel tank capacity 4600 Litres

YDM4 - YDM4 class 1350HP meter gauge diesel electric locomotive with

DC-DC transmission, powered with DLW built 6 Cyl. ALCO251D diesel

engine, is designed for mixed traffic service, passenger or freight. The

locomotive equipped with fully equalized trimount trucks has light axle

loading and higher adhesion. The maximum speed potential of the

locomotive is 100 Kmph and is suitable for multiple unit operation.

Locomotive is highly economical and reliable in operation with high level of

performance.


Installed power 1350 HPPower input to traction under site conditions - 550 C temp. & 600M altitude

1150 HP

Gauge 1000 mm



Width (Max) 2730 mm


Locomotive weight basic 72000 Kg.Nominal axle load 12000 Kg.Wheel diameter basic 965 mm.Max. starting tractive effort 18936 Kg.Max. service speed 100 KmphFuel tank capacity 3000 Litres

OTHER PRODUCT & RELATED SERVICES:

DLW is not only fast emerging as a global powerhouse to manufacture

locomotives and their spares but also as a single window destination offering

wide gambit of related products and services. It is adequately equipped with

state-of-the-art facilities and competent manpower to undertake: -

turn-key maintenance jobs;

design consultancies;

Techno-economic feasibility studies;

procurement/ contract management consultancies;

supply chain/ logistics management services;

high-end turn-key jobs;

project management consultancies.

DIFFERENT WORKS AT DLW:

UNDERFRAMES & SUPERSTRUCTURES

Precision cutting and forming of sheet metal is utilised for manufacture of superstructures including drivers cab, engine hoods, and compartments for housing electrical equipment. All activities connected with pipes like pickling, bending, cutting, forming and threading of pipes of various sizes are undertaken in another well-equipped work area. In yet another work area, all electrical equipment is assembled in the fabricated control compartments and driver’s control stands.Underframes are fabricated taking all due care to ensure designed weld strength. Care is taken to impart the requisite camber to the underframe during fabrication itself. Wherever required, welds are tested radiographically. Welder training and their technical competence is periodically reviewed.

BOGIE MANUFACTURING

Large special purpose machines are utilised for machining cast and

fabricated bogie frames. In the same work area, axle and wheel disc

machining is undertaken on sophisticated CNC machines. Inner diameter

of wheel discs are carefully matched with the outer diameter of axles

before the wheel discs are pressed onto axles, at designated pressure,

using a specially designed wheel press. The complete truck (bogie),

including bogie frames, wheels and axles, brake rigging and traction

motors is assembled before being sent onwards for locomotive assembly.

LOCOMOTIVE ASSEMBLY & TESTING

Assembled and tested engines are receive in this Shop from Engine

Division. Also, underframes, assembled trucks, superstructures and

contractor compartments are received from respective manufacturing and

assembly shops of Vehicle Division. Important alignments like crank

shaft deflection, compressor alignment and Eddy Current clutch/radiator

fan alignment are done during assembly stage itself. Electrical control

equipments are fitted and control cable harnessing is undertaken. The

complete locomotive is thus assembled before being sent onwards for

final testing and spray painting.

Rigorous testing of all locomotive systems is conducted as per laid down

test procedures before the locomotive is taken up for final painting and

despatch.

FABRICATION OF ENGINE BLOCK

Steel plates of sizes up to 80 mm thick are ultrasonically tested before

being precision cut by numerically controlled flame cutting machines.

Fabrication of engine block is completed by submerged arc welding using

semi-automatic welding machines. Down-hand welding is ensured using

specially designed positioners. Special fixtures are used for making

down-hand welding possible in inaccessible areas. Critical welds are

subjected to radiographic examination. All welders are periodically tested

and re-qualified for the assigned job.

MACHINING OF ENGINE BLOCK

The fabricated engine block is then taken up for a variety of machining

operations like planing, enveloping and end drilling. All these operations

use heavy duty planers and CNC drilling machines. V-boring of cylinder

liner bores is a process requiring a high degree of precision and is

undertaken using a specially designed machine. Recent addition of a

plano-milling centre has provided further fillip to the quality and speed of

enveloping operation. 12 Cylinder and 16 Cylinder Blocks have V angle

of 45°, whereas the 6 Cylinder Block is inline type.

COMPONENT MANUFACTURING

Over 2000 components are manufactured in-house at DLW. These include ALCO turbo superchargers, lubricating oil pumps, cam shafts, cylinder heads, chrome plated cylinder liners, connecting rods and various gears. Our well-equipped Machine Shops have dedicated lines for operations like turning, milling, gear hobbing, drilling, grinding and planing etc. In addition, DLW is equipped with a variety of special purpose machines and a large number of state-of-the-art CNC machines to ensure quality and precision.All related processes like heat treatment and induction hardening are also carried out in-house. A completely new Chrome Plating Shop for Cylinder Liners has been set up with modern infrastructure like fume extraction system and Programmable Logic Controlled material movement system.

ENGINE ASSEMBLY & TESTING

The engine block, crankshaft, camshafts, cylinder liners, pistons, connecting rods, cylinder heads, exhaust manifold, turbo-supercharger and all related piping is assembled to make a complete engine. This is followed by mounting of electrical machines like traction alternator, auxiliary generator and exciter. This power pack is tested for horsepower output and other parameters of engine health on computerised Engine Test Beds. Only after the engine parameters are found perfect the power pack is allowed to be moved to the locomotive assembly area.

What is a diesel locomotive?

Actually, it is more properly called a diesel-electric locomotive. The

concept is relatively simple: An oil-burning engine turns an alternator or

generator which in turn produces electricity that powers traction motors

that connect to the axles of the locomotive. This process is much more

efficient than the external-combustion steam locomotive.

The gasoline engine, like in an automobile, has a thermal efficiency (the

conversion of fuel into work) of 8 or 9%. The diesel engine, however, has

a thermal efficiency of about 30%. Unlike in a gasoline engine in which

the fuel is ignited by spark plugs, the fuel in a diesel engine ignites

because of the air pressure inside the cylinders. The air in the cylinders is

raised to about 500-600 psi which raises the temperature inside to about

1000 degrees F. Oil injected into the hot air ignites and expands. The

expanding gas forces the piston to move down and this turns the

crankshaft that is connected to the generator(DC) or the alternator(AC)

where electricity is produced. When the piston rises again from the

momentum, the gas is expelled from the cylinder and the cycle begins

again. The generator or alternator then provides power to the traction

motors. Then you're on your way!

Why was diesel engine developed? Diesel engines came about to replace steam. Even though the original

British Rail Modernisation Plan of 1954 specified that electric trains (which

already existed on the former Southern Railway in the form of 3rd-rail D.C.

electrification) should replace steam directly, because of the amount of

bureaucracy involved -BR was a large organisation, and still bureaucratic to

this day- meant that diesels were needed as a stop-gap measure before the

money could be found to electrify all the tracks. The decision to phase out

steam had been a political one, to give an illusion of development. In actual

fact steam locomotives were fine examples of industrial machines. They

were reliable even with the minimum maintenance, and when kept in

pristine condition they performed well. The relative sophestication of a

diesel locomotive in fact posed an operational handicap: better maintenance

facility was needed in order to ensure reliable operation, and as a result of

the additional equipments needed, the early diesels were relatively low in

power output, with the class 40 at 2,000hp almost at the top of the range

whilst large, powerful express passenger steam locomotives routinely

produced 2,500hp or more. Indeed in the early years diesels were often

called in pairs to haul trains which previously just one steam locomotive

would have had no problem handling.

The ‘Diesel advantage’

One of the many advantages they offered over steam, even in their early

years, is that they were very much more fuel efficient, and less polluting,

since they do not churn out a large amount of smog-causing soot. They also

offered better working conditions for the engine crew. No more was the

tunnel a locoman’s nightmare, instead of driving practically blind through

the dark with smoke filling the driving cab, the motormen now enjoyed

clean, closed cabs without all the smoke and the dust, and had small lights to

illuminate the line ahead. The ‘upgrade’ was not welcomed by all engine

crew. To run a passenger steam express at 80mph and keep it at that speed

require real skill from both the driver and the fireman, but the same is

relatively easy to do in a diesel. It also meant that the fireman’s job became

redundant and they became ‘secondmen’ on diesel-hauled trains, to simply

assist the driver since the driver’s absolute attention to the the signal ahead

is becoming more vital as train speeds are pushed higher and higher.

Interestingly, in the States they were never re-named as secondman, as a

result the dubious practice of carrying a ‘fireman’ on diesel trains persists

until today, even though the job description has changed somewhat, the

‘fireman’ is more like a diesel mechanic.

It is wrong to think that in the early days diesels were more powerful and

faster than steam counterparts. This becomes apparent when one examines

the world speed record for a diesel is 148mph, whereas for steam it is

126mph, and the diesel record was set some 50 years later since the

LNER’s; it had the extra half-century in between to develop.

The transmission system.

At low speeds diesel engines have very little torque (turning force) and when

stopped they have no turning force at all, engines have to be spinning to

provide some traction. This presents a technical problem, because if the

engine crankshaft was connected directly to the wheels like it is in a steam

locomotive, it would not be able to provide any force to accelerate the train

from rest. Cars and road vehicles get around this by a gear/clutch system,

otherwise known as a mechanical transmission system. The clutch allows

the engine to engage stationary wheels without having to slow down, and the

gears allows the engine to keep the spinning at sufficient speed to keep the

torque up.

Clutch/Gear systems were used for the very first diesel trains around, indeed

I have travelled on one and its a very strange experience, just like being on a

bus. However the forces involved are much greater on a train than on a road

vehicle, and gearboxes couldn’t really take it, and caused a lot of friction

too, further reducing the efficiency. Besides, diesel engines, being

compression-ignited, have a very small margin of optimal spin speed.

Efficiency drops off very sharply if the engine runs just slightly faster or

slower, unlike petrol-engines which do not have as tight a limitation. But,

the speed at which the wheels spin at 5mph differs dramatically from that at

80mph! To build such a gearbox would require perhaps some 15 different

gears. Even the best rally-drivers would probably find it extremely difficult

to change gears that fast, especially on commuter services where one may

not even reach top speed between adjacent stations or signal checks. As any

truck driver would know, an articulated lorry has up to 9 gears for a similar

reason, in order to keep the engine revs at its optimal value and to make sure

enough tractive effort is produced, faced with a wide variety of gradients.

Truck-trailers are only permitted to travel at up to 50mph in Britain, if one

attempt to build a 100mph diesel locomotive out of mechanical transmission

one would soon run into problems. An automatic transmission would be

pointless, as the efficiency loss in such a transmission would render the

‘diesel advantage’ in the early days practically nonexistent.

The electric transmission.

The solution was to use an Electric transmission. Electric motors have very

high torque just when stationary. If you take two electric motors, wire them

into each other, then if you turn one of them, the other one will turn. This

principle is used in diesel engines, the engine turns one of the motors and the

other is connected to the wheel axle. This is an excellent way of transferring

the power. The to start the train the engines roar up, spinning the motor very

fast. This puts a high potential difference across the axle motor bringing in

enough torque to start the train moving off and accelerating.

The inside schematic diagram of an English Electric class 47 diesel-electric locomotive.

Over 500 examples of this locomotive was built in the 1960s and it became one of the

most common, general-purpose standard type of all times, with a top speed of 95mph.

Over 250 examples still exists today.

Brief History Dlw

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