The idea of distributing the weight of a vehicle over a greater area than that provided by its own wheels is by no means a novel one; one year after Cugnot produced the first steam automobile Richard Lovell Edgeworth patented a device whereby a portable railway could be attached to a wheeled carriage; it consisted of several pieces of wood which moved in regular succession in such a manner that a sufficient length of railing was constantly at rest for the wheels to roll upon. The principle of this device was but a modification of that upon which the tracks of tanks now depend, and all subsequent ideas were founded on this basis.[12]
The endless chain track passed through various early patents. In 1801 Thomas German produced “a means of facilitating the transit of carriages by substituting endless chains or a series of rollers for the ordinary wheels.” This definitely cut adrift from the idea of wheels and replaced it by that of tracks. In 1812 William Palmer produced a somewhat similar invention, and in 1821 John Richard Barry patented a contrivance consisting of two endless pitched chains, stretched out and passing round two chain wheels at the end of the carriage, one on each side, which formed the rails or bearing surface of the vehicle.
Footed wheels were not, however, abandoned, and in 1846 a picture of the Boydell engine shows the wheels of this machine fitted with feet. In 1861 an improved wheel-foot was patented by Andrew Dunlop which was modified by other inventors and by degrees evolved into the pedrail, trials of which were carried out at Aldershot under the War Office in 1905.
In 1882 Guillaume Fender of Buenos Aires suggested and John Newburn patented certain improvements to endless tracks. Fender realised that the attempts to produce endless travelling railways had not met with great success owing to the shortness of the rails or tracks employed; he, therefore, proposed that their length should be the same as the distance between the vehicle’s axles. If it were desired to have short links the number of wheels must be increased; furthermore, should the tractor be used for hauling a train of wagons, the endless track should be long enough to embrace all the wheels. This is the original idea of the all-round track.