RAILWAY CARRIAGES 1900-2000

Perhaps the only certainty of the Twentieth Century was change – and the design of railway carriages was no exception: evolving from the kind of wooden vehicles that George Stephenson would have recognised in 1900 to extruded aluminium Pendolino sets at the turn of the new Millennium. In this article Mr F.W. Sinclair C. Eng. F.I.Mech.E , Chartered Mechanical Engineer and former Chief Engineer of the Gloucester Railway Carriage and Wagon Company Ltd, looks back at some of the design issues that the period threw up in the face of modernising motive power, higher train speeds and increasing demands for passenger safety and comfort.

Queen Adelaide's London & Birmingham carriage of 1842

WHEELSETS

Much more is now understood about the behaviour of coned wheeled tyres on the rails and great improvements in riding performance and comfort to passengers have been achieved as a result. Solid rolled wheels were a great advance over the Mansell or spoked wheels used in earlier years and the introduction of roller bearings gave an even greater reliability and required little service maintenance.
Axle design has been greatly improved and all axles are now recommended to be machined and cold rolled to avoid any insipiency, which might lead eventually to fatigue and breakage. The old bronze bearing axle box incorporating white metal linings was still being used well into the third part of the century and there seemed to be a reluctance to use roller bearings at the time. However, the change was most successful and much of the maintenance necessary with the old type box was then avoided.

Four and six wheeled wooden bodied carriages, early 20th Century

BOGIES

Before the intensive use of welding, the bogie side frames were joined to the headstocks and crossbars by angle knees and rivets but in later years "all weld" designs were becoming more common. Unfortunately some of the first efforts at completely welded bogie frames very unsuccessful, because it was found that the locked up stresses in the frames due to the contraction of the welding had to receive special consideration. The London Underground experiment with completely welded frames resulted in any frame, after welding, having to be subjected to heat treatment to relieve the joints where the weld had occurred. The problem was solved by joining welded side frames to the headstocks and crossbars with angle knees and rivets.

Wooden bodied Southern Railway bogie carriage

SUSPENSION

The bogie suspension, on which much of the ride quality of the vehicles depended, had always to be carefully considered. It was generally thought that a frequency of one balancing cycle per second, under full load, was the best that could be achieved from vehicles with laminated springs over the axle boxes and either elliptical or helical springs in the floating bolsters. In the latter half of the century however helical springs were used over the boxes and bolsters pushing laminated springs out of fashion. With the later introduction of hydraulic damping further improvements in ride quality have been achieved.

LMS Stove 6 wheeled brake van

BRAKING

During the first half of the century, in the age of steam, the main braking system was vacuum, which was obtained through the train pipe from an ejector in the locomotive cab using steam from the boiler. In the mid 1920s when the Southern Railway was formed the commuter services were electrified and Westinghouse brakes were introduced. This air brake system is used all over the World now and is becoming increasingly common as electrification continues. Indeed, all standard gauge carriages cleared for use on Railtrack metals are now air or air and vacuum dual braked and even some preserved steam locomotives have been fitted with air pumps to increase their utilisation.
Similarly, most passenger carriages in 1900 were fitted with clasp brakes; applying two blocks per wheel. These brake blocks were generally of cast iron or composite material, which required frequent maintenance. The old type of braking system also tended to cause some damage to the tread of the tyres, and flats were found when "pitting and spawling" of the tyre periphery was experienced. Automatic slack adjusters appeared in the second half of the century and are commonly used now to prevent this. London Underground Tube stock vehicles were even fitted with independent brake cylinders, each cylinder incorporating its own slack adjuster. This left room underneath each car where space was extremely limited. In the last half of the century too, disc brakes has arrived and the troubles associated with rattling brake gear have all but disappeared.

British Railways Mark 1 Corridor Brake Third

CONSTRUCTION

Railway carriages carrying passengers throughout the world in the Twentieth Century generally survived for many years, probably half a century. Even the most heavily worked subway passenger vehicles - electrically propelled, with high performance characteristics and operated twenty hours a day - built by the Gloucester Carriage and Wagon Co Ltd for the subway in Toronto were specifically designed to last for eighteen years. They in fact survived forty years before being taken out of service. Broadly speaking three different types of construction for passenger cars could be discerned: the earliest being of all wooden frames and bodies; followed by bogie vehicles with steel trussed underframes carrying wooden bodies of various types, some incorporating steel panels and rolled channel pillars. From 1980 however nearly all construction was all metal and integral, giving increased security to passengers in the event of a mishap. Many of the early two or three axled coaches survived into the middle of the 1920s when the railways of the United Kingdom were amalgamated into four main Groups. In fact on the Southern Railway many of these older coach bodies - which were of teak supported on steel trussed underframes - were used to form the bulk of the vehicle accommodation for the commuter services of its South Eastern section. However, passenger carrying vehicles on British railways have improved enormously since then and the days are long gone when a train of wooden bodied carriages arriving at a station would appear with a guard’s van next to the tender of the locomotive purely in the interests of safety. Similarly, all modern carriages use electricity for light, heat and cooking - rather than the oil and gas lamps and stoves which sadly proved lethally flammable in accidents in the past. Old fashioned slam doors – operated by passengers leaning out of the vehicle – are also being phased out in favour of central locking or power operated plug doors: in both cases operated remotely by the guard.

Monocoque built BR Mark 2 Manchester Pullman carriage

OPERATIONAL REQUIREMENTS

The railways of a modern industrialised country have to provide both long distance main line travel facilities and commuter services around highly populated areas such as south east England and London. In both cases, the trains provided are just as likely to be diesel or electric multiple units as the traditional rakes of locomotive hauled carriages. Although more flexible in the face of fluctuating loads throughout the working day, locomotive hauled trains have the time penalty of the locomotive uncoupling and running around the carriages at each terminus rather than the multiple unit driver simply changing cabs. A hybrid solution to this problem is the semi-fixed formation train with a locomotive at one end and driving trailer at the other, thus allowing a failed locomotive to be quickly changed: although such an arrangement tends to be less sure-footed than its multi- powered- axle alternative.

Monocoque built BR Mark 3 Restaurant Buffet

DESIGN

Passenger safety is always paramount, although multiple unit commuter vehicles have also to provide for crush loading at peak times. In particular, passengers surging in and out of the doors in stations cause particular problems with very large doorway openings needed on such trains. This alters the design of the integral all-steel coaches being built today and and multiple unit car bodies have to have very careful attention paid to the wide doorway section of structures, particularly the connection between cant rail and longitudinal solebar member.
On the other hand carriages used on main line routes cater for comfort over long periods of travel and their entrance doors at either end of the vehicle pose no structural problems for the designer. However, the travelling public of the year 2000 with a choice of rail, car, coach and aeroplane travel is much more demanding than that of a century before. In addition to toilets, they will expect an inter city railway carriage to provide an adequate catering service ( if only a well stocked trolley ), comfortable seats ( in both First and Standard Classes ), central heating and air conditioning. Indeed, the latter development has prompted a move away from ventilators mounted in windows to sealed double glazed panoramic units. This phenomenon, combined with open saloon interiors replacing compartments and corridors, means that the railway passengers of today have a better view of the world rushing by than ever before! As an alternative though, the next generation of passenger rolling stock may well feature seat-back audio and video facilities.

Traditional carriage construction techniques

THE FUTURE

In an article of this kind it is not possible to do more than refer to a few of the improvements that have appeared over the last one hundred years. However, with the arrival of the new Millennium and passenger traffic increasing appreciably an exciting prospect confronts the companies that build, lease and operate trains. At present all members of the British railway community are engaged in a reorganisation of the system :- and are making strenuous efforts to improve all aspects of railway operation. Large orders for rolling stock have been issued including tilting trains, and when these appear the travelling public should be much more comfortable, travelling at high speed in safety - with greatly increased efficiency - and arriving on time at their destinations. Hopefully, with further electrification and the supply of trains with increased acceleration and braking characteristics the travelling public will be drawn back to the railways just as it was in 1900.