Rubber in Railways
Rubber, both natural and synthetic, is used in a wide number of
applications on railways. These may be divided into the following broad
Rubber components used within a railway environment, but unmodified from use elsewhere: e.g. tyres for road vehicles used to assist in railway operation. The adaption of pneumatic tyres for railway use is an interesting topic promoted by the Michelin organizaation. Great progress has been made in France, especially on the Paris Metro..
Rubber used for civil engineering: railpads between rail (or sole plate) and sleeper; vibration isolators for railways (this is a complex area and will require some expansion, subsequently), water-stops for tunnels, early application in turbo-alternators.
Rubber used in mechanical engineering, either as hose, transmission belting, or most importantly as a spring material (special attention needs to be given to isolating vibration from diesel engines and electric motors), as an element in buffing and drawgear, and as a vital element in suspension systems.
Rubber is an unusual material, and one which used to cause engineers considerable difficulty. The way in which it is compounded and shaped, and especially if it is bonded to metal, has a significant affect upon its behaviour. Like any other part of engineering there were a number of key players who greatly assisted in the development of rubber as an engineering material: these were Peter Lindley, Hirst and Payne. It should be emphasized that most railway vehicles, from the reliable sprinters used to link West Runton with the rest of the planet to the TGVs use rubber (that is natural rubber) in their suspension, as do tramcars.
Horse-drawn vehicles had been fitted with rubber suspension more than a century ago and the Cowey system developed about 1908 employed inflated air bellows to improve the ride of early motor-cars on solid tyres. The much better known, and more widely adopted, Firestone Airide system was originally developed over fifty years ago. Scammell Lorries, a British firm, had been fitting solid rubber springs for the suspension of the rear axles on its heavier (12-15 ton) trucks from 1933. In addition rubber was well-established in auxiliary bushings associated with helical and leaf springs on most vehicles. The use of rubber in civil engineering is also of long standing. Sewer rings have been unearthed in London which were installed nearly a century before. There is a railway viaduct in Melbourne where rubber was being used as a vibration isolating medium in the 1880s: furthermore in both cases the rubber was still functioning even though it had been installed when rubber technology lacked the benefits of organic accelerators, antioxidants, and antiozonants. Although rubber could demonstrate this long period of continuous usage, in 1966 it was still possible to find engineers who could state that 'rubber was surrounded by an aura of mystic' or that 'the use of rubber has led to some expensive disappointments caused in no small measure by the fact that data on rubber characteristics provided by manufacturers was not always sufficient' and called for specific information on load-deflexion characteristics, life expectancy, creep, and damping. It must be stressed that this particular contribution received extensive comment from Manser of London Transport, recording their satisfactory experience with using rubber suspension units on underground railway cars, and from the late Dr Peter Lindley of MRPRA who was able to supply the bulk of the 'missing' informationthe characteristic shape factor diagram was incorporated in the printed version of the paper.
6.2. Railway suspension systems
Macbeth analysed the amount of rubber employed in a 30 ton British railway coach and showed that 95 kg of compounded rubber was used in the buffers and drawbar and 65 kg in the suspension. In tht: former the rubber was playing the major' roles, whereas in the latter, rubber was limited to an auxiliary role. Rubber springs were also used to cushion the plate springs on many steam locomotives. Rubber has made very considerable progress in rolling stock suspensions. Chevron laminated springs are used as the primary suspension on all London Transport rolling stock, which represents the use of approximately 16 kg of rubber per car. Rubber is also used in the secondary suspension. The chevron spring was developed by A.J. Hirst of Dunlop Metalastik who was responsible for 32 patents, mainly for suspension systems during the last ten years of his life (Fig. 23.5). Chevron springs have also been used on many other urban transport systems and in freight rolling stock, especially when used on lightly constructed railways. The Swedish Railway system employs chevron springs on its high-speed train sets. The French Railways use conical laminated springs for their Train a Grande Vitesse (TGV) which runs at 250 km/h. Rubber air bags are widely used in secondary suspension systems. These both serve to isolate the body from the bogie and to provide a uniform level independent of loading.
Woodruff, W. The rise of the British rubber industry during the nineteenth century, Liverpool University, 1958.
Macbeth, C. Rubber in automobiles, RGA, 1938.
Sainsbury, J. Air springs for vehicle suspension. Rubb. Dev., 1957, 10, 38.
Smee, A.R. Century old sewer rings exposed at West Ham. Rubb. Dev., 1963, 16, 115.
Lindley, P.B. Engineering design with natural rubber. MRPRA, 1974.
Macbeth, C. Rubber and railways., RGA, 1931.
Rubber in steam railways
THE steam locomotive was a crude, dirty, and thermally inefficient machine. Most of the firemans labour of shovelling up to seven or eight tons of coal a day was wasted, mainly through the chimney, yet it was a machine beloved by many. Its fascination lay in the visible production of power, the stentorian exhaust beat, the cry of its whistle, the acrid smell of smoke, the sweet smell of hot oil and the great masses of clattering connecting rods. By the end of 1967, steam will have almost disappeared from Britainthe scene of its birthand it is appropriate to consider how rubber served this metallic beast.
Rubber has had a very long history in railway service. Only fifteen years after the opening of the Liverpool & Manchester Railway, W.C. Fuller patented buffers and supporting springs for carriages which incorporated rubber (probably GB 10894/1845 Construction of carriages for railways via Woodcroft). This development was followed by Charles de Bergue, who patented springs incorporating metal plates in 1847 (GB 11815/1847 Buffing and traction apparatus; springs for railway and other carriages). By 1853 George Spencer was able to perfect these early springs (GB 13951/1852 Springs of railway carriages, trucks and waggons) /and produce a range of products for what has remained the three most important mechanical uses of rubber on railways, namely as draw-gear, buffering and bearing springs.2
The 1850s were a fertile period for the adoption of rubber as a bearing material in locomotives; several locomotive types produced at this time were entirely borne on rubber. Both the Bristol & Exeter and the London & North Western Railway owned high-speed locomotives with springing of this type. One locomotive, built by Rothwell and Company of Bolton for the Bristol & Exeter line, is supposed to have achieved the extraordinary speed (for the 1850s) of 80 mile/h and was similarly carried on rubber units.4 Its use as a primary bearing material diminished with the improvement of metallic springs, but it remained as an auxiliary material on many railways. The footplate men seem to have appreciated the smoother ride given by these auxiliary units. When introduced onto the Great Northern Railway, drivers were reported to be less fatigued after a days work and, as late as 1935, W. F. McDermidwho was normally fortunate enough to work partially rubber-borne locomotivesrecalled his teeth chattering from vibration when riding on a locomotive without the benefit of these units.3 Economies of up to 70 percent were observed when rubber units were used in association with steel springs, owing to the reduction in vibration. The engine drivers comfort was sometimes yet further improved by the installation of rubber pads beneath the foot-plate boards.5 To eradicate the wear usual in hornblocks O.V.S. Bulleid fitted his experimental Leader design, introduced in 1948, with axle-guides in which the relative movement was accommodated by the shear deformation of rubber units housed in cylindrical pedestals. This should also have prevented the transmission of the shock-loading from the connecting rods and coupling chains.6,7
The famous Jenny Lind type originally used rubber suspension (an early form of pot bearings) on the leading and trailing axles (Lowe p. 582). The Adams bogies as developed on the North London Railway also used a form of rubber suspension (Ahrons).
The draw-gear used to connect vehicles, especially that between the locomotive and tender, was subjected to severe shock forces during acceleration and deceleration. To avoid fracture in the metallic components or damage to freight and discomfort to passengers, rubber springs were developed to absorb these shocks. Most steam locomotives used heavy counterbalances on the wheels to reduce the hammer-blow caused by the thrusts from the connecting and coupling rods but, to reduce this redundant weight, these counterbalances were reduced or abolished in later designs. In order to reduce horizontal oscillations, careful design of the draw-bar springs was necessary and, to this end, Bulleid successfully employed rubber draw-spring units in his Merchant Navy class which employed no reciprocating balance weights.8
The Avon Rubber Company (successors to George Spencer, Moulton and Company) in 1962 organized a survey of drawbar springs which had been in service on British Railways carriages for varying periods of time up to 34 years (Figures 2 and 3). There was little change in 10 years' service but, after 30 years, they showed around 10 percent set and a change in hardness from 540 to 640 Shore. As a result of this survey Avon recommended that British Railways should change the draw-gear springs after 15 years service for, although the springs could still absorb deflections of between 40 and 50 tons after 30 years in service, the lower pre-compression and higher hardness would result in greater shock transmission from starting and braking snatches.9 It should be noted that coaches are usually retired after rather less than 30 years service, which means that only one change of draw-gear springs is necessary within the life of the vehicle. Locomotive draw-springs which took the bulk of the hardest shocks were expected to give a life of 10 years.8 It is interesting to note that the same types of rubber units as used for steam are now giving satisfactory service with the far more powerful diesel locomotives.9
Anyone who had ever spent a night near a marshalling yard will appreciate that buffers have to absorb considerable impact forces. Unfortunately, no silent buffer has ever been developed; while rubber has been used in the springs for over a century, metallic plates are used at the point of impact. An examination of springs from a wagon scrap-heap shortly after the First World War showed that wagon springs could continue to function for up to 23 years. Further, at that time, one foreign railway replaced its rubber springs every 15 years.0 Although there was so much evidence to show that rubber was a highly suitable material for buffer springs it was only through the influence of Bulleid, against strong opposition from two railways, that the Railway Clearing House accepted it as an alternative standard material for wagon buffers in the 1920s. At the same time welding of wagon frames was permitted, also against strong opposition." Locomotive engineers seem to have treated non-metallic materials with apathy; one frequent fear was that of the effects of light, even though most of these units were housed in almost total darkness.
Springs play an important part in the successful operation of a railway but hose forms the very lifeline for a train, as it is used to carry the air or vacuum pressure for braking and steam for heating. The earliest railways did not appreciate the need for these services (especially the latter) and it was not until after a series of very spectacular accidents in the 1890s that continuous braking became obligatory in Britain, even though the Westinghouse air brake had been invented in the United States in 1869. Sodium acetate or hot water warming pans remained in use until this century but were rapidly displaced by steam heating by piping steam at a reduced pressure from the locomotive. Rubber hose formed the linking device between the pipes; what little material has been written about it would seem to indicate its durability. The Avon Rubber Company uses natural rubber for brake hose and experience no difficulty in service except for very occasional breakdowns owing to rotting of the canvas reinforcement. Nylon-reinforced natural rubber steam hose is also made by this company and gives satisfactory performance at about 60 lb/in.2 for up to two years.
Hose permitted the development of continuous braking but even with this greater braking potential accidents did occur. Rubber helped, however, in the reduction of damage from collisions. Shock-absorbing side buffers and more especially the buckeye-type coupler, which incorporated rubber buffing, prevented the carriages from telescopingconsequently saving many lives.0
In addition rubber was used in a great number of other applications including seals, for water hose between the engine and tender and as fairing to prevent draughts in the cab or to create a smoother exterior for streamlined trains. The A4 class, which included the worlds fastest steam locomotive Mallard, used 132 lb of vulcanized rubber2 but this was considerably less than the 600 lb which went into a typical railway carriage in 1931."
Although the age of steam is rapidly drawing
to a close, rubber, which has been successfully used for over a century,
is already playing an essential part in the transformation of the railways.
Vibration has always been one of the most serious causes of wheel wear. Rubber
rail pads and vehicle suspensions help to reduce this, but the internal
combustion engine produces its own problems owing to its inherent vibration.
Natural rubber mountings help to eradicate this trouble. A. J. Hirst's paper
on rubber suspension systems presented at 'The Use of Rubber in Engineering
Applications conference4 details many of these developments.
6. Bullied, O. V. S. Locomotive and rolling stock developments in Great Britain. Mech. Engng, 1950, 72, 455.
7. Tuplin, W. A. The ill-fated Leader. Rly Wid, 1965, 26, 413.
8. Bullied, O.V.S. Discussion on Cox, F. S. Balancing of locomotive reciprocating parts. J. Instn Loco. Engrs, 1943, 33, 218.
9. Communication from the Avon Rubber Company.
10. Glascodine, R. T. Impact of railway vehicles in relation to buffer resistance. J. Instn Loco. Engrs, 1936, 26, 209.
11. Bulleid, H. A. V. Master Builders of Steam. London: Ian Allan, 1963.
12. Communication from the British Railways Archivist.
13. Macbeth, C. Rubber and Railways. London: British Rubber Publicity Association, 1939
14. Hirst, A. J. Rubber suspension systems. Use of Rubber in Engineering, editors Allen, P. W., Lindley, P. B., and Payne, A. R. London: Maclaren 1967.
Rubber, naturallyon the right lines
'RAILWAYS ARE DYING. Amorphous generalizations of this type abound in the United States and in Britain where the over-lavish installations of the last century are being trimmed to suit present requirements. Similar pruning will probably take place over much of Western Europe in the next decade. The rest of the world has a shortage of rail communications, however, and new lines are being constructed in Russia, Canada, Africa and India. Japan plans to build a completely new network to supplement its existing, over-burdened system. No, railways in many parts of the world continue to be a growth industry as the two graphs below clearly show. Four types of traffic will probably continue to grow. These are bulk freight (especially minerals, grain and oil), container traffic, commuter traffic and medium-distance passenger services in densely populated areas.
Therefore, a market for supplying railway needs would seem to be assured for many years. But is it a market for rubber? Before answering this, it is necessary to examine the basic fundamentals of transport by rail. The secret of heavy load haulage is low friction; railways achieve this by using steel wheels on steel rails. This produces a low rolling resistance at the cost of high local vibration and noise. Indeed, continuous running at resonance is unavoidable on most railways.2 To isolate the passengers, freight or more delicate parts of the vehicle from this continuous emission calls for considerable ingenuity and it is here that rubber can afford considerable aid. Railways are immensely complicated organizations. In addition to the complexity of the system and its associated signalling, rolling stock, stations and civil engineering works, railways may operate road vehicles, ships, aircraft, docks and power stations. This survey will, however, be restricted to those engineering applications which are unique to railways.
A previous RUBBER DEVELOPMENTS3
article showed that natural rubber has been used in rolling stock for over
a century, principally in spring units for draw-gear and suspension, and
in hose. Draw-gear springs protect the couplings and frames from starting
snatches; similar units protect automatic couplers against the forces of
deceleration. In non-automatic systems the buffers, which may also employ
rubber units, take up the braking irregularities. These units are housed
in dark recesses behind the couplings and sometimes appear to be forgotten
by the maintenance teams. In China, this neglect extended to 21 years,4 but
the rubber was still giving satisfactory service. On locomotives, which take
the hardest knocks of all, 10 years service is
While the draw-gear is designed to absorb horizontal movement, the suspension system is provided to minimize the complex vertical and lateral forces generated at the track. The suspension is normally divided into primary and secondary functions but in certain simple applications the two may be combined. The former isolates the axles from the bogie, while the latter isolates the bogies from the main frames.3
Evidence of this success may be seen in the recent order for further Metalastik units for Londons first automated tubethe Victoria line5due to be opened later this year [i.e. 1967]. The trains on this deep level railway will be operated by one man, whose main function will be to reassure passengers in the event of emergency. In normal conditions he will only have to operate the rubber-edge sliding doors and press the starting button. From then on the train is 'driven by electric pulses fed from the track. It would, of course, be possible to eliminate the two remaining manual operations, but public confidence demands that someone, other than a computer, should keep a watchful eye on the line ahead. The saving in labour costs is obvious, but indirect economies will result from the optimized driving techniques, especially in reduced wear and fuel consumption. Other cities underground, or rapid transit systems, have also employed rubber units with marked success. They include Paris,10Stockholm,1 Berlin,2 and Hamburg.3 In Hamburg use of roll springs has been made on lines running through restricted loading gauge tunnels.
Above ground, railway engineers have been slower to adopt rubber suspension units8 but there have, however, been significant advances in recent years. One example of this has been the introduction of the Gloucester-Metalastik bogie. It is an extremely simple design, requiring minimum maintenance, and has found wide acceptance on many railways. Service conditions vary from the heat of Africa and Asia14 to the cold of the sub-Arctic,5 where they are used in 100-ton iron ore wagons. On poorly laid narrow gauge lines they have significantly reduced the incidence of derailments.6 The Deutsche Bundesbahn7 has been active in the adoption of rubber primary suspension. Units have included chevron, roll, shear and disc types and these have been applied to electric and diesel-hydraulic locomotives, railcars, and express luggage vans. The Swiss Federal Railways8 have graduated from installations on 14 diesel-electric shunters introduced in 1954, to a number of 6500-hp electric locomotives capable of running at 87 mile/h. Older locomotives on the Berne Lötschberg-Simplon Railway have had their springing improved by the substitution of rubber units. This has caused an improvement in vertical oscillation performance sufficient to permit raising the speed limit from 56 to 62 mile/h.
British Rail has had less satisfactory experience, as the bogies first selected for experimental modification were basically unsuitable for rubber units.8 Nevertheless, the potential maintenance reduction has persuaded them to persist. At the present time experiments are being made with roll springs for primary and air springs for secondary suspension on outer-suburban multiple units.9 Only bogie vehicles have been considered so far, but four-wheel vehicles are cheaper to construct and are suitable for freight work. Unfortunately the traditional vehicle of this type is very rigid and quite unsuitable for high speed duties. To overcome these defects, British Rail0 has developed a new concept for the four-wheeler, in which sub-frames provide some of the flexibility normally associated with bogies. These house the axleboxes whose movement is accommodated by hollow rubber springs. Naturally, a fair degree of stiffness has to be maintained between the sub and the main frames, otherwise the vehicle would be prone to derailment. To achieve this stiffness in the longitudinal and lateral planes radius arms with rubber-bushed ends are employed. Connection between the two frames is made via swing links bedded in rubber blocksthus permitting longitudinal movement in shear (see left). Under rig conditions speeds equivalent to 140 mile/h have been reached satisfactorily and it is hoped that the wagon will be able to operate in service at 100 mile/h.
Air springing is employed in conditions subject to severe loading fluctuationconditions which are met on freight and rapid transit vehicles. A typical installation is on the heavily utilized Japanese surburban railways." Other applications have been made in combination with solid rubber units and have received attention above. The advantages of air and solid rubber springing are combined in the recently introduced AirMetacone6 secondary suspension which is cheaper and more compact than all-air springs. Unladen, the weight is carried solely on the rubber units but as the load increases the air maintains a constant vehicle height. Trials with this unit are being conducted on the Stockholm and London Underground railways. Air springs are also being employed in the gas turbine powered high speed trains which are to run between Toronto and Montreal in Canada. They also feature in British Rails advanced passenger train project which would be capable of speeds up to 150/mile/h."
It should not be forgotten that more modest locomotives and rolling stock gain from similar attention. The new Rolls-Royce Steelman,3 an industrial shunting locomotive, incorporates rubber primary suspension. This interesting locomotive, with its carefully arranged controls, has won a Council of Industrial Design Award for 1968. An even more modest application has been made on the carriages of the Festiniog Railway4a line operated by enthusiasts for the perpetuation of century-old steam locomotives. Fare paying passengers do not appreciate last centurys suspension techniques, however, so new carriages have been equipped with rubber units. Further, rubber auxiliary units are incorporated in many systems which employ steel springs. These have given satisfactory service for many years and an examination of some after 10 years running showed them to be in sound condition.5
Resilient wheels appear to be a useful means of reducing noise, but have not found much favour on railways, although are widely used on street tramways [added 2003]. On the mile long Southend Pier there is an electric railway, a rapid transit system in miniature, using resilient wheels on the rolling stock6a seaside pier should, after all, be a haven of quiet away from the restless din of town life, but when their length is appreciable, the foot-weary demand transport. Streetcars, similarly equipped in the United States, were completely silent at a range of 80100 yd.7 They also gave satisfactory service on steam railcars. The Howden-Meredith wheel may, perhaps, be considered as a variant of this type. Ordinary road vehicles were equipped with steel tyres on top of the rubber road treads. In this form buses could take to the rails and operate on quiet branch routes. They were very successful in Ireland and ran for over 20 years with the original sets of rubber tyres.8 This has been a popular subject for the railway enthusiast press.
From this, it is a logical move to the total abolition of steel rails and tyres and their replacement by rubber tyres and concrete track. During the 1930s Michelin were very active in the field of rubber-tyred railcars which were capable of operating on conventional track. In 1937 the 93 units in service on French railways ran 4 250 000 miles29 Some development continued after World War II and a complete locomotive-hauled 'rapide was employed on the Paris-Strasbourg route. Each coach was fitted with 20 rubber tyres.30 Later development turned away from the conventional railway towards a system which employed a concrete track for the rubber tyres, plus guide rails, thus permitting the use of standard heavy duty road tyres. In 1951 an experimental installation was made on one short Paris Metro line3 and in 1957 the system was extended to a complete route.32 Tyre service life has averaged 160 000 miles and sometimes 250 000 miles has been attained.33 The success of the system has led to its introduction on the Montreal Metro, which is the first line to be specially constructed for this technique of operation.4
Advantages of rubber tyres include lighter weight (some 1800 lighter than conventional trains), higher acceleration and deceleration (in Montreal the maximum rate of acceleration is 3 mile/h/sec), the possibility of operating on steep inclines (1:7 is claimed to be possible and 1:16 is Montreal's ruling gradient), the simple, maintenance-free track, and the relative lack of noise. On the other hand power consumption is higher and this may lead to heat dissipation problems. Extensive civil engineering work is required to convert existing systems, with which it is incompatible. On balance, this quieter railway offers an attractive form for new subsurface rapid transit systemsa form of transport which will grow with increasing city congestion. If this happens the market for rubber tyres could be very large; Paris uses nearly 6000 tyres on its single route."
Another potential market for rubber tyres could be on monorails where they could reduce the noise which would otherwise emanate from above-street level. So far monorails have remained small-scale ventures and many have been either experimental0or for use in pleasure parks.37 The future does not look particulary brightat any rate in Britainas a recent report8 on Manchester traffic problems, which set out to compare all known forms of urban transport, recommended 'duo-raila new euphemism for railways.
So far vibration has been considered as a direct function of the track and the vehicle or as induced through acceleration. The use of internal combustion engines has led to another source of vibration which rubber mountings and couplings can effectively isolate. Engines treated vary in size from small industrial locomotives, such as the Steelman to 4000-hp giants like the Kestrel locomotive, which is one of the most powerful single-engine diesel-electric locomotives in the world. Rubber units may also be used to protect the relatively sensitive electric motors from forces generated at the track. Layrub couplings have operated on Swedish electric locomotives for many years9 and at temperatures as low as 40C. Bushes, manufactured by Silentbloc, for resilient gear wheels have been examined after a quarter of million miles service and have been judged suitable for further punishment.40
All that has been written so far is indicative of the care taken by the railways in finding the smoothest possible ride for their freight and passengers. But further protection is necessary and is, of course, supplied. Delicate freight may require individual attention and can, with advantage, be isolated from its surroundings by rubber mountings.4 Perishable foodstuffs and certain chemicals have to be maintained at low temperatures during transit, and expanded ebonite, which has a thermal conductivity of only 0~20 Btu, is a very useful insulating material.4 Passengers require further cosseting and this means more rubber. Foam rubber seating for day4 and mattresses for night44 ensure that the passenger is at least as comfortable as at home. Rubber flooring, which may be latex-cement,4 or solid rubber, or even foam backed carpeting, helps to exclude noise. Rubber draught excluders on doors, windows and gang-ways also help to make the journey more pleasant. When heating is required, hose is provided to link the individual coaches to the boiler on the locomotive. This hard pressed commodity has a serviceable life of 23 years. Other hose carries the compressed air or vacuum which actuates the brakes throughout the train. To ensure the highest standards of comfort some 600 lb of rubber were used in an average British carriage of 1931."
Noise and vibration from railways may make the siting of buildings difficult, especially in the centre of cities. Normally the problem is tackled by isolating the building with rubber mountings situated in the foundations. This technique has permitted luxury flats to be sited immediately above busy lines.46 These are the Albany Court flats adjecent to St James on London Transport. This may appear to be of greatest interest to builders, but the railways gain from selling the air space above their tracks. In large-scale developments it may prove to be cheaper and more satisfactory to silence the railway rather than to treat individual buildings.
For example, an entire section of Central London (the Barbican) was being redeveloped. As a railway ran through the centre of the site it was necessary to quieten it; this was achieved by constructing a new track formation on a series of concrete rafts within a cut-and-cover tunnel. These rafts are isolated from the rest of the area by 'floating them on rubber bearings.47 This development has now seen service for forty years
Many of the railways own civil engineering works are over a century old, but still give yeoman service; most were built before rubber had been discovered as a material for civil engineering. The changing pattern of communications is altering this. New road construction leads to renewed bridge building activity where the two forms of transport intersect and modern techniques, such as rubber bridge bearings, are employed. The first rubber bridge bearings in Britain were used in a structure which straddled a railway.48 Changing patterns of railway traffic with an accompanying increase in loads had led the railways to rebuild many of their older bridges, especially where lines have been electrified.49 Older bridges can be improved by the substitution of rubber units0 for worn-out roller or sliding bearings. Where road and rail cross on the level, rubber strips may be provided in place of the more usual wood planks to give the motorist a smoother passage."
Keeping water in its place
Water exclusion is one of rubbers premier functions, therefore it is not surprising that rubber is finding increasing favour underground. A new method of tunnel construction has been facilitated by the use of waterstops; this is the immersed tube technique, which has been employed for the Rotterdam Metro." Water seepage may be a problem in older tunnels and this can be eradicated by pressure grouting the walls with latex-siliconate compositions." Later installations of thje submerged tube technique included the BART System in San Francisco where the tunnels are protected from seismic shocks by huge natural rubber seals: these functioned as intended during a major earthquake.
Freight and passengers require terminal facilities and the flooring of these may extend to several acres. Road making techniques have to be employed and rubberized bitumen has been used to mitigate the effects of pounding feet on station concourses.4 Travellers nerves are by tradition frayed but peace and quiet can be established in waiting rooms and offices by using solid rubber flooring.5 The weary traveller may also be helped on his way by rubber-capped moving staircases and passenger conveyors.6 Freight requires more specilized facilities. Conveyor belts aid package handling. Hose is used for transferring bulk materials, such as powders, but in some instances it is still easier to invert the freight wagon to empty its contents. Rubber fenders are employed on the tipping plant to prevent wagon damage during this operation.57
This survey has not included all the potential railway applications mentioned in RUBBER DEVELOPMENTS. Rail pads, which offer a considerable market for rubber, are discussed in a separate article in the next issue. Docks, which are treated in the previous article in this series (part I, page 12), are closely associated with railways. Other applications are so diverse that a catalogue rather than an article would be required to list them.
Pros and cons
Some railway engineers still tend to approach rubber with ultra-caution.
One eminent engineer8 recently stated that rubber was surrounded
by an aura of mystery in the 1950she was referring to no more distant
decade than the 1950s [please note the antiquity of this
paper]. He also inferred that 70 mile/h is the maximum operating
speed for rubber suspension despite the fact that the French have run an
experimental railcar," with rubber secondary and partial primary suspension,
at 144 mile/h. [It is worth mentioning that the writer of these articles
subsequently travelled on the Swedish tilting train and on Eurostar
and the TGV at considerably higher speeds was far in the future, then, but
that is what good science is about]. Possibly boyhood experiences of punctures
in bicycle inner-tubes and perished hot water bottles make certain engineers
consider rubber an ephemeral material, but rubber used in bulk for engineering
purposes displays entirely different qualities. A parallel attitude would
be to allow corroded, cheap steel toys to affect ones choice of girder materials.
Yet rubber has been used to reduce noise, vibration and maintenance costs
for over a century, so why does the suspicion remain? There has been no lack
of communication between rubber researchers and railway engineers. Many articles
have been published to bridge any remaining gaps. Several are included in
the references and mention must also be made of Engineering Design with
Natural Rubber6 -which has been widely
distributed. Conferences have been organized, the latest one being the Use
of Rubber in Engineering; several references to this have been made in the
bibliography. Lastly, specialist staff from NRPRA are prepared to contribute
to professional meetings of engineers6 or meet them individually.
1. High speed 2400-mile rail system planned for Japan. Rly Gaz., 1968, 125, 4.
2. Hirst, A.. J., Rubber suspension systems. Chapter 13. Use of Rubber in Engineering, Ed. Allen, P. W., Lindley, P. B., and Payne, A. R., London, Maclaren, 1967.
3. Jones, K. P., Rubber in steam railways. Rubber Developments, 1967, 20, 13.
4. Cantile, K., Discussion on Koffman, J. L., and Fairweather, D. M. S., Rubber as an aid to suspension design. J. Instn Loco. Engrs, 1966-67, 56, 331.
5. London Transport. Statistics, 1967.
6. Graff-Baker, W. S., Considerations on bogie design with particular reference to electric railways. J. Instn Loco. Engrs, 1952, 42, 306.
7. Rubber suspension for railway rolling stock. Rubber Developments, 1957, 10, 74.
8. Manser, A. W., Discussion on Koffman, I. L., ibid 4.
9. The automatic trains for Londons Victoria Line. Engineering, 1968, 205, 325.
10. New trains for Paris Metro. Mod. Rlys, 1968, 24, 155.
11. From Stockholm to Sydneyrubber sprung trains. Rubber Developments, 1963, 16, 30.
12. Light alloy coaches for the Berlin underground. Rly Gaz., 1968, 124,340.
13. Tappert, H., Discussion on Koffman, J. L.,ibid,4
14. Rubber-spring bogie wagons for Ghana and Malaysia. Rubber Developments, 1965, 18, 107.
15. Sinclair, F. W., Discussion on Koffman, J. L., ibid, 4.
16. Cornwell, E. L., Rubber in rail vehicle suspension. Mod. Rlys, 1967, 23, 475.
17. Kniffler, A. Discussion on Koffman, J. L., ibid, 4.
18. Loosli, H., Discussion on Koffman, J. L., ibid,4.
19. Koffman, J. L., Primary suspensions for coach bogies. Rly Gaz., 1968, 124, 108.
20. Advanced freight vehicle suspension. Design & Compon. Engng, 1967, (15), 42.
21. Tohara, H., Rubber suspensions for Japans railways. Rubber Developments. 1960, 13, 103.
22. Gunston, W. T., Railways of the future. Sci. Jnl. 1967, 3, 34.
23. Rollys-Royce Steelmnan rides on rubber. Polymer Engng News, 1968,1,6.
24. Working on the mountain line. John Bulletin, 1967, 20(4), 16.
25. Burnham, J., Discussion on Koffman, J. L., ibid, 4.
26. Resilient wheels for electric trains. Rubber Developments. 1949,2(2), 33.
27. Tritton, J. S., Discussion on Graff-Baker, W. S., ibid, 6.
28. Pneumatic tyred rail buses. Rubber Developments, 1954, 7, 14.
29. Macbeth, C., Rubber and Railways. London, British Rubber Publicity Association, 1939.
30. The train on pneumatic tyres. Rubber Developments, 1949,2(1), 15.
31. Ruhlman, H., Pneumatic tyres on the Paris underground railway. Rubber Developments,, 1951, 4, 114.
32. Pneumatic-tyred trains on the Paris Metro. Rubber Developments, 1957, 10, 77.
33. Parkes, R., Montreal's rubber-tyred Metro. Mod. Rlys, 1966, 22,420.
34. Pneumatic tyres for new Montreal underground. Rubber Developments, 1965, 18, 33.
35. Pneumatic tyres for new Montreal Metro. Rubber Developments, 1967, 20,9.
36. Rubber in overhead railways. Rubber Developments, 1957, 10, 24.
37. Britains first monorail rides on solid rubber tyres. Rubber Developments, 1967, 20, 34.
38. Duorail recommended for Manchester rapid transit. Rly Mag., 1968, 114, 10.
39. Crane, G. R., Flexible couplings on Swedish railways. Rubber Developments, 1967, 20, 64.
40. Communication from Silentbloc.
41. Allen, D. C., Use of rubber in shock packaging. Chapter 17. Use of Rubber in Engineering, ibid. 2.
42. Mitchell, 1-1., The use of expanded ebonite for thermal insulation. Rubber Developments. 1950, 3, 6.
43. Smee, A. R., Luxury in modern rail travel. Rubber Developments, 1961, 14, 65.
44. Dunlopillo in Australian trains. Rubber Developments, 1952,5, 132.
45. Cormac, P. B., Rubber-latex-cement compositions. Rubber Developments, 1955, 8,46.
46. WaIler, R. A., Flats isolated from vibration. Rubber Developments, 1966, 19, 91.
47. Clayden, K. J. C., Noise and vibration attenuation in the Barbican scheme. Use of Rubber in Engineering, ibid, 2.
48. The use of rubber in bridge bearings. Rubber Developments, 1957, 10, 34.
49. British Railways in 1958. Engineer, 1959, 207, 8.
50. Berridge, P. 5. A., The use of rubber in expansion bearings under existing bridges. Rubber Developments, 1960, 13, 117.
51. The worlds first rubber level crossing. Rubber Developments, 1955, 8, 8.
52. Rubber versus water in Rotterdams new metro. Rubber Developments, 1966, 19, 145.
53. Hurst, H., Pressure grouting damp masonry. Rubber Developments, 1968, 21, 37.
54. Rubberized bitumen underfoot. Rubber Developments, 1955, 8, 90.
55. Womens whims boost rubber floors. Rubber Developments, 1963, 16, 57.
56. Moving into the future on the rubber-covered walkway. Rubber Developments, 1964, 17, 57.
57. Rubber fender for tippler plant. Rubber Developments, 1952,5,92.
58. Koffman, J. L., and Fairweather, D. M. S., Rubber as an aid to suspension design. J. Instn Loco. Engrs, 1966-67, 56, 441 (Paper 682).
59. French Railways experimental gas-turbine multiple unit. Mod. Rlys, 1967, 23, 410.
60. Engineering Design with Natural Rubber. NR Technical Bulletin, NRPRA, 1966.
61. Lindley, P. B., Discussion on Koffman, J. L., and Fairweather, D. M. S., ibid, 58.
Note both the late Drs Lindley
and Payne considered that Koffman's paper was an utter disaster as he had
no idea of how rubber behaves as an engineering material.
Further consideration was given by KPJ to innovation within the raiway industry concerning rubber components in The evolution of new uses for natural rubber (with R.E. Brice) in A.D. Roberts' Natural Rubber Science and Technology. Oxford University Press 1988.
Kruckenberg bogie suspension, using rubber balls, was developed by the LNER with Spencer Moulton (see Newsome)
The Coventry railcar with Michelin pneumatic tyres: illustration from John Alsop (LPC 9094) of Fowler 2-6-4T 2389 hauling passenger brake and flat bogie wagon with film crew filming railcar on Bushey troughs; notes from Mike Christensen concerning problems of track circuits and the detonation of detonators (the former is still a problem with lightweight vehicles); from Peter Swift concerning the four types evluated in Britain: Type 9 with bonnet and articulation (evaluated on SR and LMS in January to April 1932), Type 20 with two eight-wheeled bogies with raised driver's cab at one end demonstrated on LMS in 1935; the two Coventry Pneumatic railcars built in 1936/7 and operated in the Coventry/Leamington/Rugby area. The Leighton Buzzard photographs (Issue 24 page 58) are of the Type 20. Problems were track circuits, flammability of fuel, and structural weakness. There was a serious accident with heavy loss of life in France in 1947. Two citations. R.W. Kidner corrects day of test noted quoting Engineering 22 February 1935. Michael Dunn states that Leighton Buzzard footbridge was still in situ
The Adam's bogie for locomotives incorporated rubber damping: British Patent 404: 13 February 1865.
Pelham Bridge (Lincoln)
Paradigm bridge for use of rubber bridge bearings. For earlier level crossing see BackTrack 13 page 198
Resilient wheels fitted to Jersey Railways & Tramways Sentinel steam railcar.
Front and rear springs were of thick slabs of Indian rubber in circular cast iron pots. They were later changed to leaf springs as it was found that the rubber lost its elasticity very quickly. Lowe: Jenny Lind 2-2-2.
The following is taken from Jack: It was inevitable, given the age and condition of the L&B trackwork, that engine and tender springs would often fail, but they were breaking at the enormous rate of between 100 and 180 a month. Other breakages followed: "links, pins and joints - solid good material is wrenched asunder almost every trip" as McConnell wrote to the Chairman. Rubber springs seemed to offer a cure.
Shortly after Charles de Bergue had taken out his patent, in December 1847 McConnell made a trial of india-rubber springs in the buffers of one engine and tender, and early in 1849 six wagons were also fitted experimentally. In May 1852 he equipped one engine with rubber carrying-springs, and these proved so successful that in July it was arranged that his new Patent class express engines would be built with them.
The patent springs were hollow cylinders of thick rubber, confined within the socket when used for buffers, and in a brass casing, or held within iron rings, when used above or below the axlebox. The rubber cylinders were compressed endwise by pressure and were intended to return to their original form when the pressure was released.
In July 1852 400 rubber springs were purchased from Moulton & Co for £96, with more in October but supplies from this firm were stopped in March 1853 following a dispute between the various patentees. In November McConnell described J. E. Coleman's rubber springs as superior to any description in use; he had used them for twelve months, during which time there had not been a single failure. This he contrasted with the record of steel springs which were failing at an average rate of 147 each month. A year later he was still enthusiastically recommending their extended use.
In the six months to the end of November 1854 there had been 297 failures
of springs at a total cost of £466 2s 7d (£466.13): 199 engines
with steel springs: 292 failures £425 19s 3d (£425.96)
34 engines with rubber springs: 1 failure £3 2s 4d (£3.12)
4 cases or rings originally too tight: £37 1s 0d
£40 3s 4d (£40.17)
The 34 engines with rubber springs included eleven of the Patent class and the eleven Small Bloomers, and perhaps also 'Mac's Mangle' 227. The other eleven are not known.
Rubber springs were fitted to Wolverton-built engines in 1857, but in that year McConnell complained to the manufacturers, Spencer & Co, that one of their springs had "no more elasticity than a block of wood" and sent back 45 of them because they had acquired a permanent 'set'. Nothing is recorded on the subject after this and later new engines were built with steel springs. No doubt the introduction of longer rails and fishplates helped to reduce the number of failures.
Ramsbottom got rid of the rubber buffer springs soon after taking over; rubber bearing springs were gradually replaced by steel, although many tenders still had them into the late 1870s.
John Loadman's Tears of the tree: the story of rubber - a modern marvel. Oxford University Press. 2005. 336pp.
Essentially a human interest approach which concentrates on a number of key figures: Thomas Hancock (the person who discovered how to masticate raw rubber as received from producing areas), Charles Goodyear (the person who discovered how to vulcanize rubber by the addition of sulphur and the application of heat) and Robert Cross and Henry Wickham who arranged for rubber seeds to be taken from the Amazon region to the Royal Botanical Gardens at Kew to India, Sri Lanka and Singapore/Malaysia. Those provided via Wickham were imported via Liverpool and were conveyed by the LNWR to London. There are also accounts of the savagery perpetrated by the rubber barons in the Amazon Basin and in the Congo on behalf of the King of Belgium, the development of rubber processing machinery, synthetic rubber (Wallace Carothers and Waldo Lonsbury Semon) and rubber processing chemicals. There is an excellent chronolgy, a bibliography of books consulted and a remarkable index beginning "A crime against humanity" and thirty entries under "sulphur". The activities of Spencer Moulton are noted en passim: the firm and its constituents were influential in the application of rubber to locomotive suspension and other (more lasting) railway applications, notably buffers and drawgear. Those seeking how the natural rubber industry developed through plant breeding, improved agronomic practice and even through improved primary processing will have to look elsewhere.
Parsons, R.H. The early days of the power station industry. Cambridge: University Press for Babcock & Wilcox Ltd., 1939. 217pp.
Page 179: mentions that the turbine and alternator installed at the Portsmouth Municipal station (inaugurated 6 June 1894) stood on rubber blocks which rested on the concrete foundations without any form of holding bolts. Electricity generators driven by high speed reciprocating and gas engines had been highly prone to problems with vibration. It is not clear if any other turbo-alternators were isolated upon rubber blocks.
Craig, William G.
Under your web page heading Rubber in Railways there is a comment on the locomotives that were built with Indian Rubber Springs by McConnell. I can help identify and confirm that four of these McConnell designed by him and built by Robert Stephenson and Co in 1854 with J. E. Coleman Rubber springs. They were built for Sydney and Western Railway in New South Wales, Australia numbers 1 to 4. This was originally a private company but was taken over by the New South Wales Government before the railway was opened. One of these locomotives is still in existence in the Powerhouse Museum Sydney Australia. the India Rubber springs were not a success and orders were made for replacement metal springs within 2 months of the opening of the Sydney railway 26th September 1855.
Lowe page 22 notes that the Newton Moor Iron Works locomotives supplied to Platt Bros. had rectangular buffers cushioned with rubber