London Underground Electric Train E-Book

Piers Connor

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2015

Beschreibung

The London Underground Electric Train tells the story of the development of electric traction on the London Underground system. It combines technical knowledge, historical context and practical experiences, and covers the history of underground lines since the opening of the first deep-level underground rail system in the world in 1890: the City & South London Railway. The evolution of train design, including power, lighting, heating and design of the Underground cars is also covered along with the development of operational, engineering and safety devices on trains. Highly illustrated with period and new photography and technical diagrams, this book is a reference work for electric traction and underground rail enthusiasts.

Leseprobe

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THE LONDON UNDERGROUND ELECTRIC TRAIN

Piers Connor

THE CROWOOD PRESS

First published in 2015 by

The Crowood Press Ltd

Ramsbury, Marlborough

Wiltshire SN8 2HR

www.crowood.com

© Piers Connor 2015

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 014 0

Unless otherwise credited, all illustrations are from the author’s collection.

CONTENTS

List of Abbreviations

Preface

CHAPTER 1 HERITAGE

CHAPTER 2 FROM DREAMS TO WHEELBARROWS

CHAPTER 3 ELECTRIC TRACTION IN LONDON

CHAPTER 4 TUBE CAR BODIES

CHAPTER 5 BRAKES

CHAPTER 6 DOORS

CHAPTER 7 BOGIES

CHAPTER 8 AUXILIARIES

CHAPTER 9 SAFETY

CHAPTER 10 BREAKTHROUGH

CHAPTER 11 TRAIN FORMING

CHAPTER 12 ONE-PERSON OPERATION (OPO) AND AUTOMATIC TRAIN OPERATION (ATO)

CHAPTER 13 MODERN EQUIPMENT

CHAPTER 14 THE NEED FOR CAPACITY-WHAT NEXT?

Bibliography

Index

LIST OF ABBREVIATIONS

ATO (Automatic Train Operation).

ATP (Automatic Train Protection).

BTH (British Thomson–Houston) The British arm of the American General Electric Company (GE, q.v.) that supplied the bulk of the Underground’s electric traction equipment until the 1980s.

BW (British Westinghouse Electric & Manufacturing Company) A company set up in 1899 to sell Westinghouse electrical products in Britain. Later became Metropolitan Vickers (q.v.).

C&SLR (City & South London Railway) The company that owned the first electrically operated tube railway in London, which eventually ran from Clapham Common to Euston via the City. It is now the City branch of the Northern line.

CLR (Central London Railway) The company set up to construct and run the tube railway between Shepherd’s Bush and Bank. It became part of the Underground Group.

CSDE (Correct-Side Door Enable).

CTBC (Combined Traction/Brake Controller).

ECEB (Electrical Control of Emergency Braking) Introduced for the 1973 Tube Stock to replace the Westinghouse brake as the on-board safety brake system.

EMI (Electro-Magnetic Interference).

FACT (Fully Automatic Control of Trains).

GE (General Electric) The American company originally founded by Thomas Edison that was formed when Edison’s company was absorbed by the Thomson–Houston company.

GEC (General Electric Company) The UK company founded in 1886 that only first supplied the Underground with electric traction equipment in 1923.

GNPB (Great Northern, Piccadilly & Brompton Railway) The official company title of the Piccadilly Line in its early days.

GTO (Gate Turn Off) (thyristor) A type of electronic switch used in 1990s traction power circuits to vary power in DC motor control.

HSCB (High-Speed Circuit Breaker).

IGBT (Insulated Gate Bipolar Transistor) Now a common component in electric traction power circuits. Replaced GTOs.

LER (London Electric Railway) A company formed in 1910 by amalgamation of the Baker Street & Waterloo Railway (the Bakerloo Line), the Charing Cross, Euston & Hampstead Railway (the Hampstead line) and the Great Northern, Piccadilly & Brompton Railway (the Piccadilly Line).

LNWR (London & North Western Railway) The name of the company that owned (amongst other routes) the West Coast main-line route from London Euston to Watford, Birmingham and northwards to Carlisle.

LU (London Underground).

MAR (Motor Alternator Rectifier).

MG (Motor Generator).

MU (Multiple Unit) System for controlling distributed power and other equipment on a passenger train from one driving position.

MV (Metropolitan–Vickers) A company formed from the original British Westinghouse company and Vickers that supplied electrical equipment to the Underground.

NTfL (New Tube for London) The design proposals for new tube rolling stock published in October 2014.

OMO (One-Man Operation) Used until replaced by the more politically correct OPO.

OPO (One-Person Operation).

PCM (Pneumatic Camshaft Mechanism).

PDC (Passenger Door Control)

PEA (Passenger Emergency Alarm).

PEAB (Passenger Emergency Alarm Brake).

PWM (Pulse Width Modulation).

RTT (Round-The-Train circuits).

SAPB (Spring Applied Parking Brake) Automatic parking brake used on Underground trains built from the late 1970s.

SCAT (Speed Control After Tripping).

SDO (Selective Door Operation).

UERL (Underground Electric Railways of London Ltd) The holding company set up in 1902 to finance the electrification of the District Railway and manage the completion of the tube railways then under construction. It became known as ‘the Underground Group’ and it later absorbed some London bus and tram operations.

W&C (Waterloo & City Railway) The tube line built by the London & South Western Railway in 1898 between Waterloo and Bank and taken over by the Underground in 1994.

WJS (Watford Joint Stock) A tube stock fleet partially owned by the LNWR and partly by the LER. It was built in 1920 to work the Bakerloo service to Watford over the ‘New Lines’ built adjacent to the LNWR main line out of Euston.

PREFACE

The century and a half that has passed since the first Underground line in London opened in 1863 has seen huge advances in technology. The greatest of these has been the development of electric traction, which started 125 years ago in London with the opening of the City & South London Railway (C&SLR) in 1890.

This book tells the story of the advances in engineering and operations, many originally developed by American engineer Frank J. Sprague and his successors, that have pushed forward the development of the Underground’s electric trains. It shows how the trains we see today have been designed with a background of 125 years of experience and development since the opening of the C&SLR. In the book are the stories behind the various systems in use now and the reasons for the introduction of the operational, engineering and safety devices provided on trains.

This book is not a history of the rolling stock itself; rather the story of its development. Each chapter contains a bit of background, a bit of science, a bit of history and a bit of practical experience, with many illustrations showing how the basics were developed and what trains looked like through the years of their development.

Much of the information in this book is from official sources and company records, gathered over the last fifty years. During this time, I have had help from many colleagues and friends like Brian Hardy, Graham Neil, Mike Horne, Felix Schmid, Julian Galeswki, Richard Griffin, Andy Barr, Steve Smith, Ted Robinson, John Sprague, Tim O’Toole and some who, sadly, have passed, like Gordon Hafter, J. Graeme Bruce, Cyril Birkbeck, Bob Greenaway and Ernest Lumley. My thanks to those who have helped with the provision of photos and illustrations and drawings; they are acknowledged with each figure. To all these and many others I have known over the years, my thanks for their help and support, given both knowingly and unknowingly.

Piers Connor

CHAPTER ONE

HERITAGE

THE LONDON UNDERGROUND

The London Underground, known as ‘The Tube’, is the oldest of the world’s many urban rapid transit systems, the first section opening on 10 January 1863. Its wonderful heritage was celebrated in style for its 150-year anniversary in 2013, including a visit by Her Majesty The Queen and members of the Royal Family and a re-enactment of steam operation between Edgware Road and Moorgate over part of the original route. The Underground now has eleven lines and serves 270 stations, which provide services for up to twenty hours a day. The system is operated by TfL (Transport for London), which is also responsible for the provision of some main line rail services (the ‘Overground’), London area bus service franchising and surface transport facilities in the greater London area, amongst other things.

The region known as Greater London has an area of 618 square miles (1,600km2) and a population of over 7 million. Over a million people travel into central London each day for work and over 60 per cent of these use the London Underground system. Over the last fifteen years there has been a 70 per cent increase in the demand for travel on the Underground so that, more than ever before, London relies upon the Underground system as part of the social and economic structure of the city. Recently, the number of passenger journeys exceeded 4 million a day.

Tube and surface stock on test at the Bombardier factory in Derby. The smaller train on the right is 2009 Tube Stock for the Victoria Line, while the larger train is the S (subsurface) Stock. The tube car floor is about 300mm (12in) lower than the subsurface stock car and the roof is 800mm (31in) lower. A surviving tradition on the Underground is to identify sub-surface stock train types by letters and Tube Stock by the date of delivery, or close to it. EDWARD ROBINSON

The central area of London is enclosed by the major mainline railway termini and the Underground’s Circle Line that connects them. This area within the Circle Line forms the commercial heart of the capital. The area known as ‘The City’, east of Holborn, is the financial district, while the West End contains the principal shopping and entertainment areas. Until the beginning of the twentieth century there was virtually no penetration of these areas by railways but then the various deep-level Underground ‘tube’ lines were opened and there is now a network of lines covering both the City and West End zones and connecting them with many of the suburbs. The routes going out to the suburbs rise to the surface outside the central area and, in fact, some 55 per cent of the London Underground route mileage is in the open.

The Greater London area is geographically divided into two halves by the River Thames, which flows west to east across the city. In the north–south division that this causes, by far the greater proportion of the Underground system is located in the northern area. Of the 270 stations serving the system only twenty-nine are located south of the Thames, due partly to old railway company politics and partly to the nature of the subsoil in the area, which rendered tube construction difficult and expensive. In contrast with the freight-rich railway companies north of the river, the southern companies depended very much on local passenger traffic for revenue and provided a dense network of frequent services, which were electrified almost entirely by 1930. The Underground was not needed in this area.

One of the features of the London Underground is that it operates rolling stock of two different sizes. This is because, over the long period of its development, two different methods of tunnel construction were adopted.

Cross-section of the 1863-built Circle Line tunnel at Baker Street station (now Platforms 5 and 6) showing the original cut and cover construction that is still in place today. The arch and side walls are brick. The station tunnel was provided with angled shafts at intervals to admit natural light, seen on the left section. These shafts have since been covered but they now have artificial lighting to replicate their original use. The road above is the Marylebone Road. Note that the track shown is mixed 7ft (2m) and 4ft 8½in (1.4m) gauge, to accommodate trains from the Great Western Railway as well as other operators. This section is wider at 45ft 1 in (13.7m) than the inter-station sections, where the internal width is 28ft 6in (8.7m). Later tunnels were only 25ft (7.6m) wide as they did not need to accommodate the broad-gauge track.

TWO SIZES OF TRAINS

The original tunnelling method, used for the Circle Line and its extensions (now the Metropolitan and District Lines) is known as the ‘cut and cover’ method. With this method, a cutting is dug along the line of the route just deep enough to take a main-line-sized train and its track. When completed, the tunnel is roofed over and the surface restored, often with a roadway. Most of the resulting tunnels are wide enough to take two tracks, except at stations, where they are widened to take platforms and stairways. Because of their proximity to the surface, they are often referred to in London as ‘the sub-surface lines’.

The second type of tunnel is the deep-level ‘tube’ tunnel. This method of construction was adopted to overcome the huge surface disruption caused by the cut-and-cover method and it took advantage of the blue clay soil upon which London is built. Single-track, circular tunnels of about 3.4m diameter (11ft 8in) were bored at a level deep enough to reduce conflicts with water mains, sewers and other underground services. Tunnels bored since the 1930s were built to a standard 12ft (3.7m) internal diameter on straight track and widened slightly for curves.

Cross-section of C&SLR tube tunnel showing the profile of the locomotive and passenger car. The tunnels were excavated with a shield and lined with cast-iron segments to form a protective ring. The internal diameter of the original tunnels varied between 10ft 2in (310cm) and 10ft 6in (320cm) but it was increased to 11ft 6in (350cm) on the Moorgate extension. A tube line required two separate tunnels: one for each direction of running. The older, sub-surface tunnels were usually double track.

Stations usually used a large single-track tunnel for each platform. Station tunnels are generally 21–25ft (6.4–7.6m) in diameter. The greater depth of these lines (an average of 66ft or 20m) meant that lifts or escalators had to be provided for street access. The technology of deep-level tube construction was available quite early on in the development of railways but it had to await a practical means of propulsion that did not require the use of smoke and steam. At first, cable drive was considered for London’s first tube line, the City & South London Railway (C&SLR), but this was soon discarded in favour of electric traction.

CITY & SOUTH LONDON RAILWAY (C&SLR)

The C&SLR was London’s first tube railway. It was opened in 1890 between King William Street in the City of London (near the Monument) and Stockwell. It used small, four-wheeled, electric locomotives hauling a set of three passenger coaches. The original, single-track, running tunnels were only 10ft 2in (6.6m) in diameter. Intermediate station tunnels were 20ft (6m) in diameter. Later tube lines were built to slightly larger dimensions.

Scale drawing of early C&SLR locomotive showing the principal parts. One feature introduced at this time was the location of the brake pipe connection hose at roof level. The small-bore tunnel restricted the height of the vehicle and there wasn’t room for anything other than the link and pin coupler below floor level. The lowest floor level was only 30in (762mm) above rail level. It had to be raised in two steps to clear the motors. The main body structure was only 10ft (3,048mm) long. Another unusual feature was the setting of the conductor rail height below that of the running rails. It meant that wooden ramps had to be inserted at points and crossings so that the collector shoes could ride up over the running rails.

The electrical equipment of the C&SLR, including the motors and controls for the locomotives, was contracted to Mather & Platt of Manchester. The locomotive bodies were built by Beyer Peacock, who were actually better known for their steam locomotives. The C&SLR locomotives’ equipment consisted of two electric motors, controlled through a hand-operated, rotary power controller carrying traction current through exposed, live contacts connected to the controlling resistors and motors. The original controller handle rotated in the vertical plane but later locomotives had enclosed controllers with the handle arranged in the horizontal plane, like a tramcar controller. There was no driver’s safety device (deadman’s handle) – it was to be another ten years before it was invented. In any case, a second man was available who rode in the cab to assist with coupling and uncoupling.

These locomotives were tiny. With a 10ft-long body (just over 3m), they were shorter than the distance between two sets of doors on a modern tube car but they had enough power, just, at 100hp (75kW) to haul a set of three trailer cars.

For train lighting on the C&SLR, a simple two-core cable was provided down the train at roof level and was connected to three lamps in each car. Connections between cars were along the roof, with sockets and a jumper cable between vehicles. The brake control pipe (later known as the train line) was also connected at roof level. The lights were fed directly off the DC traction supply and would reduce to a dull red glow when the line voltage dropped on uphill gradients or at busy times.

THE WATERLOO & CITY (W&C)

The next electric railway to be opened in London was the Waterloo & City Railway (W&C). I have to include it in this story, first because it is now part of the London Underground empire, although it was in main-line ownership for almost 100 years and second, because it had three major technical distinctions: it was the first tube railway to be allowed cables carrying motor current between cars; it was the first to adopt the duplex floor configuration for its cars, which became a standard for London Underground for the next forty years; and it was the first to be built to the American standards adopted on most of the new electric fleets built for the Underground’s electrification.

The W&C was opened in 1898 by the London & South Western Railway as a means of getting their incoming business passengers from their terminus at Waterloo to ‘Bank’ in the City of London. There were no intermediate stations, just the two termini. It was built with single-track tube tunnels like the C&SLR but with a 12ft 1½in (3.7m) internal diameter. The line was electrified at 500V DC, using a centrally positioned third rail. The larger tunnel allowed the third rail to fit centrally under the vehicle couplers instead of being located off-centre as it was on the C&SLR. The voltage was upgraded to 600V in 1917.

A sketch of a W&C motor car, showing the general layout and split-floor arrangement. The floor level was raised over the motor bogie to provide room for the traction motors. The trailer wheels were designed to protrude through openings in the floor, which were covered by seats. This was the first example of what became the standard tube motor car design, which lasted for almost forty years.

The electrical equipment was supplied by Siemens Bros, the UK arm of the German company. Werner Siemens began his electrical business in Germany in telegraphy. His successes in this field led to his development of other electrical devices like a dynamo and a motor. His brother, Wilhelm, ran the UK branch of the company from 1850, selling Siemens’ electrical equipment here. The company was successful in running a telegraph line 11,000 miles (17,700km) from London to Calcutta in 1870 and Wilhelm (by now thoroughly Anglicized and sporting the name William) was knighted by Queen Victoria. Back in Germany, his elder brother was also doing well, being ennobled by the Kaiser and becoming Werner von Siemens. In 1881, Werner opened a short tramway in Berlin using 180V DC electrified running rails. Over the next fifteen years they developed electric motors for industry and railway traction and, in 1896, the company equipped a 3.5 mile (5.6km) long underground railway in Budapest.

In the W&C contract, Siemens provided the generators for the power station at Waterloo and the electrical equipment for five four-car trains. The car bodies were built by Jackson & Sharp of Wilmington, Delaware, USA, by coincidence the same company that built the Chicago South Side Elevated cars that Sprague electrified in 1897. Locomotives were not used. Each train had a motor car at each end with space for forty-six seated passengers and a cab with the power controller at the leading end. There were two fifty-six-seat trailer cars between them.

Each motor car had a bogie at the leading end with a large, 60hp motor on each axle. Like the C&SLR locomotives, the motors were gearless, the armatures being mounted directly on the axles. The wheels of these bogies were 33in (828mm) in diameter and the car floor was raised from the 1ft 10in (560mm) level of the main part of the car to 3ft 2½in (978mm) to clear these wheels. A small section of this floor was provided with a longitudinal row of three seats either side of the car, which passengers could access (carefully minding their heads in the process) up a pair of steps.

The power controller was huge – a roughly 4ft cube, which sat in the middle of the cab and protruded through the cab front making it look like an old motor lorry. The driver sat on the left-hand side and controlled the power through a large wheel linked to a rotating drum inside the controller box. There were eight power positions on the controller.

The motor bogie of a W&C motor car with the cab end of a motor car immediately behind. The current collector shoe can be seen at the front of the bogie. It was similar in design to that of the C&SLR, being a hinged flap. It was mounted on a wooden block attached to the front of the motor case. The huge motors can be seen occupying most of the space between the wheels. The motor armatures were mounted directly on the axles.

The rear car was connected electrically to the front car through eleven power cables that ran along the car roofs, so that the driver controlled both cars from the front. The eleven cables were necessary to allow the driver to control the motors at both ends of the train in a series-parallel configuration. This was the first example of a deep-level tube railway being allowed to run motor cables between cars. Drawings show the cables were hung in a row over the entrance platforms between cars. They were semi-permanently coupled and suspended from chains attached to the overhanging roof canopies. As the height of the canopy from the floor was 7ft 8in (234cm), it seems it was quite possible for a passenger to touch the cables.

An electric motor with the armature fitted around the axle. The C&SLR, the W&C and the CLR all adopted this design on their original electric trains. It removed the need for expensive and noisy gears but it limited the torque of the motor. This design was used on a C&SLR locomotive. It begs the question as to how difficult it was to fit the case with the field coils inside it around the armature without damaging the windings.

The 500V DC current was collected by a single shoe attached to the leading edge of the front motor frame and another attached to the leading edge of the trailer bogie. The current rail ran along the centre line of the track and the top of the rail was at the same level as the top of the running rails. To avoid the shoes touching the running rails and causing a direct short, when negotiating points and crossings, wooden ramps were fitted at each location. These lifted the shoe 1½in (3.8cm) above the running rail so they could cross without touching it. The shoes were almost 1ft (0.3m) wide to allow them to bridge the gap in the ramp where the rail passed through. This seemingly fragile concept seems to have worked and a somewhat similar version was adopted by another new line, the Central London Railway.

Detail from a photo showing a set of points in the CLR’s Wood Lane Depot c. 1925. The current rails have wooden sections added to the ends where rail cross their alignment. The wooden sections allowed the wide shoe to ride over the running rail without touching it. The outline of the shoe is added to demonstrate how it worked. Note also how the ends of the current rails are anchored to the sleepers to prevent them moving out of alignment. The photo also shows how the short, curved section of current rail slopes down where it joins a straight section of rail. This is to prevent the shoe striking a blunt end of rail. The wooden safety ramp between the two joining sections of current rail performs a similar function. The final thing that this photo shows is that the depot uniquely used flat bottom rail, spiked directly to the sleepers in American style. On the main line, rails were bolted to sleepers. LT MUSEUM/AUTHOR

A completed CLR locomotive coupled to a train at the Wood Lane depot. There are no current rails. An overhead wire system has been installed over the yard and at least two locomotives are said to have been fitted with trolley poles to allow them to shunt vehicles around the yard. Date believed to be mid-1900. B.R. HARDY

THE CENTRAL LONDON RAILWAY (CLR)

By the time the Waterloo & City Railway had opened in August 1898, another new tube railway in London was close to completion. This was the Central London Railway (CLR). It opened in July 1900 and ran from the City of London (Bank) to Shepherd’s Bush – the prime route in London then and still a prime route today.

The CLR learned from C&SLR experience that the tunnels should be a little larger, so they adopted a standard of 11ft 8¼in (3.56m) on straight track and 12ft 5in (3.78m) on curves. The diameter narrowed to 11ft 6in (3.50m) at the entrances to stations where the tunnels were lined with concrete. Like the C&SLR, the CLR adopted locomotive haulage for the trains, so it was necessary to change locomotives at each end of the line. Both lines used the well-tried arrangement at termini where an arriving locomotive was uncoupled from its train and then waited until another locomotive had been coupled at the other end and had taken the train away on its next trip back down the line. The arriving loco was then run clear of the platform, where it was held in a short spur as the departure locomotive for the next train. This was a reasonably efficient solution for the day but it did involve the provision of an additional locomotive for each terminus.

As we’ve seen, the CLR was electrified with a central positive conductor rail but at 550V DC (instead of 500V) and set with its top surface 1½in (3.8cm) higher than that of the running rails (instead of level). Like the W&C, wooden boards were used at point and crossing work to guide the collector shoes clear of the running rails and the shoes were 1ft (0.3m) wide to allow the gaps between boards to be bridged. The similarity with the W&C system allowed the Central London to send one of its locomotives there for testing.

With the intention to operate seven-car trains, the CLR locomotives were larger and heavier than the C&SLR machines, weighing 44 tons (44,704kg) each, more than four times the weight of the C&SLR locos. They had four gearless motors, so that the unsprung weight was 33 tons (33,528kg). This soon began to cause trouble. Suffice for me to say here that the locomotives caused such high levels of vibration along the line that the Central London was forced to replace them, as we shall see.

The other Underground lines operating at this time, the District and Metropolitan, plus the Circle line, which they shared, were all worked with steam locomotives. The tunnels were dirty, stuffy and full of smoke and steam. Towards the end of the nineteenth century, there were moves to convert the routes to electric operation but electric traction was new technology and expensive. The new tube railways had been costly to build and operate and the return for their private investors was small. This made financing new electric railways very difficult. In those days all railways in Britain were privately owned and operated.

CLR locomotive drawing with known dimensions added. The basic layout is almost as built but the air reservoirs are omitted and the layout of the resistor grids was not as shown here. It is interesting to note that there are no axlebox springs. I have added the lighting socket. One of these was provided at each end of the locomotive. The only indication of how the locomotive was orientated is in the location of the handbrake wheel. This is on the south side of the locomotive. The driver was on the north side. Another item not shown is the steel cover over the twin buffers. With this in place the overall length increased to 29ft 11in (912cm).

CHAPTER TWO

FROM DREAMS TO WHEELBARROWS

A DREAM

In America, on 26 July 1897, for one 10-year-old boy a dream came true. He got a brand new train set to play with. This was unusual in those days, since toy trains were rare and expensive, but this was no toy. This was a full-size train. He was given the controls of the first six-car electric train to be assembled at the General Electric Company’s works in Schenectady, New York, and he was allowed to drive the train along the test track in front of the assembled officers and engineers of the Chicago South Side Elevated Railway. The boy’s name was Desmond Sprague and he was the son of one Frank Julian Sprague. He was showing off his electrical engineer father’s system of multiple-unit control, which Dad was trying to sell to the Chicago South Side Elevated.

Chicago South Side Elevated car on a demo run in 1898. The driver’s cab is the cubicle on the right. Sprague himself can be seen second from the left, standing in the back of the cab. The conductor looks like he’s been dressed by the French Foreign Legion. The rest of the riders are company officials and their hangers-on. The general design of the car was to be adopted for the first electric fleets of most of the Underground lines in London.

Well, sell it he did. The demonstration was a resounding success (‘Hey, it’s so simple, even a kid can drive the train’) and, within twelve months of this demonstration, the whole of the Chicago South Side Elevated system had been converted from steam to electric traction with 120 multiple-unit cars. Electric trains, operating under the same principles that their engineers would recognize today, provided a frequent, high-capacity urban transit service and set a new system of railway operation on a path of development that continues to this day. Perhaps it’s just as well they didn’t know then that, over 100 years later in Britain, it would take twelve months just to write the safety management system as part of the process of getting permission to operate the railway, let alone re-equip a whole railway. Sprague, who was not troubled by such bureaucracy, proudly noted later that his invention caused the shares of the Elevated company to treble in value. Doubtless, being a smart man, he had some of his own.

General Electric GE57 motor rated at 50hp as used on the Chicago South Side Elevated electric cars in 1898. The drive pinion is clearly visible on the right. This type of motor was hung on the axle and the axle bearings can be seen on the two front corners of the case. This general design of DC motor survives on the Underground to this day. What is surprising is the very small diameter of the bearings for the axle to pass through. It was quickly learned through frequent breakages that axles had to be thicker to withstand the daily duty cycle. Axles are larger and more robust today. Also, the gears shown here are straight cut. Modern gears are helical, being cut at an angle.

Sprague’s conversion of the Chicago South Side Elevated Railroad to electric traction was not without its troubles. During the early months of 1898, while the newly converted trains were being delivered and tested, one of the cars caught fire. It was quickly found that the cause was electrical and that a large batch of the resistor grids was defective. Seventeen of the twenty cars by then delivered had to be taken out of service that day. Suffice to say, teething troubles with new rolling stock are not unique to modern times.

Two traction motors showing more recent developments. In the foreground, one from the Bakerloo’s 1972 Tube Stock, type LT115A(79kW or 105hp) and, in the background, a smaller LT130 (46kW or 62hp) motor from the Central Line’s 1992 Tube Stock.

SOME HISTORY

Victorian Britain was very conservative in its approach to railway technology, largely because railways were privately owned. The owning companies had shareholders to satisfy and making money from railways was always a precarious business. New technology cost money and, unless it could be seen to make financial sense, no board of directors would allow it on their railway. Nothing new there then. In the late nineteenth century, electricity was new technology and it was considered expensive and high risk. Most UK railways ignored it.

Power circuit schematic of series-parallel motor control system, as used on the London Underground. The sequence chart shows how the power applied to the motor is controlled. This system was the basis for all UndergrounD Stock power control systems until the 1990s.

In the US, most existing railways also eschewed conversion to electric traction. It was technically difficult at that time to electrify over long distances and the capital costs would have been too high to see a reasonable financial rate of return. For short distances and heavily used street tramways, it was a different story. Most of these used horse-drawn tramcars, while the others were cable-operated. Horses were expensive to keep and maintain, requiring at the very least, stabling, water, hay, shoeing and disposal of dung, with vast amounts of labour to provide these facilities. Conversion to electricity showed that operating expenses could be slashed, quoted in one early case as being halved. So it was the street railway operators who first adopted electric traction and it was they who caused it to spread widely in urban transport. Some densely used main lines later adopted electric traction but it was in the field of US urban transport that the early development flourished, so it is there that our story starts.

MORE DREAMS

In the Sprague family, Desmond hadn’t been the only member with a dream. Back in 1881, Sprague senior visited London to attend an electrical exhibition at the Crystal Palace. During his visit he travelled regularly on the steam-operated lines of the London Underground and he became convinced that here was a system that needed conversion to electric power. He wanted to rid the tunnels of steam and smoke and he had a dream that, one day, electric trains would do the job. He told the story later that he seriously considered staying on in London just so he could achieve that dream. He didn’t stay then – electric traction technology had not developed sufficiently to allow its use on railways – but his dream did come true when his multiple-unit electric traction system replaced steam in London some twenty-four years later.

Sprague’s invention of the multiple-unit system was gradually developed from his involvement, first with electric motors and then with lifts. Sprague, who was born in 1857, began his career in 1878 as an engineer in the US navy. His interests were in the field of electricity and, after spending some time at sea and in Europe (including his visit to London), he left the navy in 1883 and, for a few months, worked for Thomas A. Edison on setting up electric light systems. Realizing that his real interests lay in electric motors and in equipping railways with them, later that year he set up the Sprague Electric Railway & Motor Company. With financial help from Edison’s company, he developed a successful constant speed, static electric motor and, by May 1885, Edison was selling the motor under his name.

Sprague was already looking at the electrification of railways, particularly urban railways and, in early 1886, he demonstrated an electrically driven flat car on a section of the steam-operated Manhattan Elevated Railroad in New York City. In this instance, Sprague was demonstrating the use of electric motors to drive a train, not multiple-unit control, which he was to develop later. At that time, he just wanted to sell motors to urban railway operators.

Although the Manhattan company didn’t take up the idea of electric traction then, enough people saw it as the future for urban rail transport to enable Sprague to gather a group of investors to put together offers to equip street tramways with electric traction. Their first contract was in Richmond, Virginia, where they had to finance, build and equip a 12-mile (19km) long street tramway, complete with power station, overhead wires, track and forty two-motor equipped, four-wheeled tramcars within an heroic ninety days allowed for the whole job.

BIG BANG THEORY

Rather strangely, although Sprague tested his electric motor on the Manhattan Elevated RR, they didn’t adopt his ideas until early in the twentieth century. The story goes that, during his demonstration on the Manhattan Elevated in 1886, he frightened Jay Gould, the autocratic head of the railroad, when a fuse blew with a loud bang as Sprague was driving the demonstration car. Gould jumped off the car and refused to get back on, believing that he was in danger of his life. Perhaps this was why the Manhattan was the last elevated to convert to electric operation. Sprague later admitted that he had been over-enthusiastic in his operation of the master controller and attempted to accelerate too fast, which is why the fuse blew. The idea of an overload relay instead of a fuse came later.

The contract was signed in May 1887. Sprague said later that his contract had a ‘superabundance of reckless confidence’, especially since his contract to supply forty motors was roughly equal to the number of electric traction motors that had been built anywhere in the world over the previous ten years. And, of course, he didn’t manage to open the line in ninety days. There were lots of technical problems, mostly because of the poor quality of the civil engineering work. Sprague himself caught typhoid fever in the middle of it and spent several weeks in his sick bed and several more convalescing.

Commercial operations in Richmond eventually began in February 1888, when they soon learned, first-hand, the problems of operating electric traction in freezing conditions. Sprague describes how, to get the ice off the overhead wire, a man had to climb on to the top of the tramcar and knock it off with a broom. They also had a very early lesson on EMI (electro-magnetic interference) when the local telephone company complained about the hissing and crackling on telephone calls caused by current leakages from the tram system and sued them to prevent them using an earth return circuit. Fortunately for the future of electric traction, they lost their suit.

Sprague lost financially on the Richmond job (amounting to about $1.2 million in today’s money) but it was the first complete, long-distance, commercially working electric tramway in the world and it led to his company eventually getting over 100 contracts to supply electric traction systems. Because he was already successfully selling electric motors for static industrial use, he had enough money to save him from bankruptcy after the Richmond losses, and he had enough for further research and development in electric traction. He didn’t have the market to himself, however, as a new organization appeared in the eastern US called the Thomson–Houston Company, based in Lynn, Massachusetts. This company, in its British form, was to develop a long and fruitful relationship with London Underground and, in my time as an Underground train driver, it was a name I saw every day, imprinted on the top of the master controller in the cab.

A typical product of BTH – a master controller, as supplied around 1906, for an electric train driving position, with the cover removed to show the control circuit contacts. The key-operated reverser switch is on the left (with the key in place) and the controller handle on the right. A spring-loaded button in the handle acted as a ‘deadman’ facility. The button had to be held down while the controller was in a motoring position. If it was released, the power was switched off and the train brakes applied. Generations of drivers up to the present day would attest that the button, which is still in use on the Underground’s battery locomotives, is uncomfortable to hold down for a long time.

THOMSON AND HOUSTON

Elihu Thomson was born in Manchester, UK, in 1853 but his family emigrated to Philadelphia when he was five. He went to university there and, after graduating, he was asked to stay and teach chemistry. He did this for a while but his real interest was in electrical engineering and, in 1880, he formed the American Electric Company with a fellow teacher, Edwin J. Houston. They began by developing arc lamps and generators, and they were soon so successful in selling them that they obtained finance for expansion and moved to a new factory in Lynn, Massachusetts, under the name of Thomson–Houston. Thomson was the chief engineer and the company was run by a local businessman, Charles A. Coffin.