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Frank Brannon, suitably attired in
period costume, who has been campaigning the re-created |
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During the late 18th century several engineers considered constructing mechanically propelled carriages to avoid the need for horses which required a lot of arable land which could be better used to feed Britain's rapidly expanding population. James Watt, the leading manufacturer of industrial steam engines even went so far as to take out a patent on a carriage propelled by a steam engine. In the event he did not pursue the idea becuse he realised that the condensing engines of the time produced too little power relative to their weight, to be of practical use on the road. Watt's rival, the mining engineer Richard Trevithick, was promoting the use of the new 'high pressure' steam engines which some, including Watt, considered to be dangerous and he had developed these to a stage where they had become lighter and more efficient than Watt's engines. When Watt's patent ran out Trevithick built a prototype road locomotive at Camborne, Cornwall and in 1801 he ran this for several hundred yards up a hill with several people hanging on to it. Unfortunately, while they were in a pub celebrating the event, it set fire to the shed it was in and destroyed itself. Undaunted, the following year Trevithick took out a patent fo a passenger carrying steam road carriage, also describing other uses for his new high pressure engines. The steam carriage was assembled at Felton's carriage works at Leather Lane, London, many of the engine components having been brought from Cornwall where they were made. The engine may have been tested in another machine called the Tuckingmill locomotive which was reported to have been stuck on the road between Camborne and Redruth 'because its wheels could not get sufficient grip of the road', but for which unfortunately no drawings are known to have survived. On completion, the London Steam Carriage was driven about ten miles throught the streets of London to Paddington and back through Islington with seven or eight guest passengers, the streets having been closed to other vehicles. This was the first trip of a self powered passenger carrying vehicle in the world. It is worth mentioning that the Frenchman, Cugnot, had built tractors for towing Napoleon's guns about thirty years earlier but these were slow moving and were not built to carry passengers. During a trip on a subsequent evening, Trevithick and his colleague crashed the carriage into some house railings and as a result of this and lack of sales the vehicle was scrapped, the engine being sent to work in a mill making hoops for beer barrels. Ultimately the project to build a steam powered passenger carrying veicle was not a success. It was too expensive and it needed two men and a bag of coal to do what a horse drawn vehicle could do with one man and a bag of hay. |
Trevithick diversified and went on to build the world's first railway locomotive but like many great innovators he was ahead of his time and despite a period in South America building pumps to drain silver mines he eventually died in poverty. The eight foot diameter wheels were intended to smooth out the road surfaces of the time so as to avoid the fire being shaken out. The forked piston rod reduced the distance between the single cylinder and the crankshaft and was considered a particular novelty. Spring operated valve gear was used to minimise the weight of the flywheel which overcame one of the drawbacks of the industrial engines. The Replica. Not all of the details of the machine are known but the patent drawings have survived, as have the drawings made at the time by a naval engineer who was sent to examine it. Further information was recorded later from eye witness accounts. Although there is no specific drawing of the carriage body, it's builder, Felton, published detailed drawings of his horse drawn carriages just before building the carriage for this machine and these tended to be very similar to a standardised design which fits the frame shown in the patent drawings. The replica carriage was constructed to this design but modified to have the door at the front and the seats sideways, there being insufficient room for doors at the side. As reported at the time, this modification allows more passengers to be carried. The boiler design has had to be modified slightly to meet modern safety standards but the principal dimensions and features have been retained. A spring safety valve and a sight glass have been added. It says a lot for Trevithick's skill that the new boiler is probably about 100 kg heavier than the original for the same performance. A more effective brake has been added which augments the simple block rubbing on the flywheel. Although the machine clearly had a water tank there is no drawing for one but poetic licence has resulted in a beer barrel being used for the purpose, Felton's works being next door to a brewery. There are two features of the patent drawing which may have been incorporated by Trevithick to put off unlicensed copiers; if the engine is assembled as drawn it would only run backwards and if the water pump was arranged to be driven by the valve spring, it would certainly have run unevenly, if at all. Two extra wheels have been added in the valve indexing mechanism to overcome this. The water pump has been connected to the crosshead as in most of his industrial engines. The replica is intended to reproduce the machine with its original performance or at
least to be the first prodcution machine to Trevithick's drawings. |
| Technical Data. The engine is a high pressure simple expansion steam engine with feed water pump, heater and steam blast. A cylindrical boiler is mounted overhanging the rear axle, made from 6.5 m.m. thick wrought iron. Single cylinder, double acting, mounted horizontally, inside the boiler, made from cast iron. Spring operated four way valve for steam. The engine runs in one direction only. |
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| Engine. | Working pressure: |
2 bar |
| Cylinder bore: | 140 m.m. | |
| Stroke: | 762 m.m. | |
| Capacity: | 11.7 litres x 2 | |
| Power: | 3 h.p. (2 kW at 50 rpm) | |
| Fuel: | coal | |
| Steering: | Tiller directed to single front wheel. | |
| Transmission: | Separate gear drive to each rear wheel. Driver can select drive to either or both wheels. | |
| Brake: | Driver operated lever applying a block to the rim of the flywheel. | |
| Speed: | 13 kilometres per hour. | |
| Range: | About 15 km with 180 litre water tank. | |
| Dimensions. | Length: | 4,905 m.m. |
| Width: | 2,184 m.m. | |
| Height: | 3,454 m.m. | |
| Driving wheel diameter: | 2,438 m.m. | |
| Weight empty: | 1.9 tonnes. | |
| Chassis: | Wrought iron and wood sandwich. | |
| Body: | To carry up to eight people. | |
| Cost in 1803. | For building the coach less the engine: | £207. |
| Shipping engine from Falmouth to London: | £20 14s 11d. | |
| Cost of engine: | Not known. | |
Information supplied by T. Brogden, Macclesfield 22.5.98 |
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