The oldest item in The Tank Museum is the Hornsby tracklayer or tractor, Little Caterpillar – a steam-powered tracked vehicle, trialed by the War Office for potential use in a combat situation.
David Roberts, Managing Director of Richard Hornsby & Sons of Grantham, Lincolnshire, designed a form of caterpillar track which he applied to a Hornsby, single cylinder tractor in 1904. He was not the first, the British inventor Richard Lovell Edgeworth had proposed what he termed a portable railway as early as 1770, although it was only a drawing. It was followed by a steam driven plough fitted with tracks which was actually built by the MP John Heathcote in 1837, and a number of inventors came up with designs throughout the 19th Century of which the American Batter, or Baxter tractor was one of the most impressive. It was designed in 1888 and featured a vertical steam boiler although as far as is known it was never built.
Development of the tracked tractor
Roberts’ tracks were not simple; they involved a system of interlocking links of wrought iron with wooden inserts in each alternate link where it made contact with the ground. The track was also designed to ‘lock-out’ at a certain point, which meant that it could not flex in a reverse direction but instead provided a smooth path for the machine, in effect a portable railway, when it crossed rough or swampy ground. Roberts’ 1904 tractor and another tracklayer based on a 40hp Rochet-Schneider car, modified in 1907, appeared in a short Bioscope film that was shown in the ‘Empire’ Music hall in Leicester Square, London in 1908.
Prior to this the 1904 tracklayer had been examined by the War Office Mechanical Transport Committee in 1905 but had not really been designed with military use in mind but more for agriculture or heavy haulage over difficult ground. While the tracked Rochet-Schneider car took part in the 1907 Aldershot Review, an exclusively military event attended by members of the Royal Family. At this event the car towed a tracked trailer fitted with a dummy wooden gun, or at least the profile of one, which is said to have been suggested by Major W E Donohue, the Inspector of mechanical transport for the Army Service Corps.
Donohue is also said to have suggested at one stage that a Hornsby tracklayer, fitted with an armoured cover and equipped with machine-guns might prove useful. While in 1908 the newspaper The Morning Leader actually commented “Here is the germ of the land fighting unit when men will fight behind iron walls.” In that year, 1908, Roberts’ tracks were fitted to a 75hp Mercedes car, clearly designed for more rapid movement since it did not feature Roberts’ complicated suspension system. Later, fitted with an enlarged radiator and sun canopy it was sent out to Egypt, presumably for desert trials.
In 1907 Hornsbys had fitted tracks to the 1905 military tractor that had proved so successful in the War Office trials as a wheeled vehicle. This makes it the first tracked vehicle to enter service with the British Army and therefore probably any army at all, it was powered by a two-cylinder Ackroyd heavy oil engine rated at 80hp and was also one of the largest vehicles built for military service at the time. Steering was by braked differential assisted by compressed air at 80 psi although the compressor had to be hand charged with a manually operated pump. Trials were conducted with the Hornsby tracklayer pulling what appears to be a sixty pounder gun. This was a six inch coast defence gun mounted on a wheeled carriage, the whole thing weighed about 12 tons and seems to have been well within the tracklayer’s capabilities.
This tracklayer was apparently scrapped in 1914 but before then it appears to have been heavily modified, mostly by being cut down in size. But apart from a photograph seen of it in this condition no details are known to survive.
In 1909 Hornsby came up with another design for the military, which was known as the Little Caterpillar. Some sources say that it was one of five or six such vehicles but in fact there was only the one. The others were all wheeled tractors. The Little Caterpillar is the one that survives in The Tank Museum collection at Bovington; still theoretically in full working order although it has not been run for about twenty years. It is powered by a six-cylinder engine, probably of Hornsby’s own make.
At first it was arranged to run on paraffin which gave an effective power output of 70 bhp. This was due to the fact that until 1911 the British Home Office had a prohibition on vehicles carrying, or towing ammunition being fuelled by petrol which they believed was too volatile. After 1911 the tractor was modified to run on petrol and the power output immediately increased to over 100 bhp. When running on paraffin the fuel was stored in three large drums at the back but there was also a small tank, above the engine, which contained petrol. The tractor would be started on this and then run for about half-an-hour until the evaporator was hot enough when it could be switched to paraffin. The chimney at the front, behind the radiator, was the exhaust pipe.
The Mechanical Transport Committee of the War Office required the tracklayer to weight no more than 8 tons 8 cwts, but also to be capable of moving itself a short distance when stripped down to 7 tons for shipping. Notice that this tracklayer has toothed track sprockets at each end, the rear set are the driving sprockets. Steering was normally achieved by unlocking the differential, which was locked for straight running, and a band brake applied to one side or the other by winding the steering wheel. However for sharp, skid turns it was possible to release a dog clutch in the rear sprocket hub on one side or the other and then applying the brake. If it was desired to use the winding drum, or winch, which was located on the rear axle on the left side, both dog clutches were released by lever from the cab. However since this also meant that the brakes would not work they were applied at the front instead, which is why the vehicle has sprockets at both ends.
The tractor was fitted with a four-speed gearbox with separate reverse. A footbrake acted on the main shaft to slow it down when changing gear and the front sprockets were fitted with a pawl and ratchet device for use when the vehicle was moving backwards. The Little Caterpillar was tested at artillery camps on Salisbury Plain and in North Wales, mostly towing artillery up to and including the sixty pounder gun. Reports suggest that it did this very well although dyed in the wool artillerymen still preferred match teams of horses. Mounted troops complained that it was smelly and noisy and that horses would not pass it. Even so it undertook some quite long distance road runs and was latterly relegated to the M T School of Instruction. During the First World War, for some reason, it was stationed at Avonmouth Docks near Bristol where an Army Service Corps team, under, it is said, Sir John Carden, was responsible for handling Holt tractors imported from the United States, before they were shipped over to France. After the First World War it took part in what was then called the Royal Navy and Military Tournament.
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