David Roberts (engineer)
From Wikipedia, the free encyclopedia
David Roberts was the Chief Engineer and managing director of Richard Hornsby & Sons in the early 1900s. His invention, the caterpillar track, was demonstrated to the army in 1909.
He joined Hornsbys in 1895 as Chief Engineer. In 1903, the War Office offered a prize of £1000 to produce a tractor that could haul a load of 25 tons for 40 miles without stopping for fuel or water. Hornsbys entered an 80hp 12 ton tractor which was the only entrant to complete the 40 miles, subsequently running on to 58 miles before running out of fuel.
Roberts, from this experience of the War Office competition, had the vision to design a vehicle for the British Army which would be able to traverse unstable ground. Vehicles such as Hornsby's 12 ton tractor would quickly be hindered by waterlogged surfaces with wheels sinking in mud. On July 23 1904, his patent (No. 16,345) obviated this problem, with a vehicle where two pitched chains of links and pins with cross bars and blocks of metal and wood to make contact with the ground are passed around the front and rear sprocket wheels, one on each side of the vehicle and form a track. The weight of the vehicle body (and engine) is taken by side brackets provided with curved pathways or bearing surfaces resting on rollers which, in turn, are supported on the chains, or on rollers of large diameter revolving on fixed pins. With this arrangement, when the vehicle is running the body is, so to say, rolled forward on the chains. Steering may be accomplished by varying the speed of the driving sprocket wheels on either side of the vehicle.
He submitted four other patents in later years, including No. 16,436 on July 14 1909, which involved Improvements in and connected with the Driving Axles of Chain Track Tractors and Locomotives.
In 1905, a Hornsby 20hp 17 ton tractor was fitted with a chain track. In July 1905 and February 1906, it was demonstrated at Grantham to representatives from the War Office. In August 1906, the 1903 competition-winning tractor was fitted with chain tracks. On testing this vehicle in July 1907, the word caterpillar was first used to describe the machine (by British soldiers). In May 1908, this vehicle was demonstrated to King Edward VII and the Prince of Wales at Aldershot, who were introduced to David Roberts.
Hornsbys bought a 40hp Rochet-Schneider car, powered by a petrol engine in 1906. It was fitted with a chain track and was trialled by the Army in November 1907 in Aldershot. The 4 ton vehicle achieved speeds of 15mph over difficult terrain. Hornsbys, in a rare moment of marketing savoir-faire, commissioned a film of this vehicle to promote the virtues of the caterpillar track, which was to be shown at provincial and London cinemas in the summer of 1908. It was often of more interest than the actual film being shown, and is apparently the first film made for commercial purposes. Roberts was looking at increasing the speed of tracked vehicles. Hornsbys bought a 75hp Mercedes car and fitted it with chained tracks with wooden wheels to test a desert environment. Tests with this vehicle on Skegness beach in 1908-9 achieved speeds of 25mph; such speeds with a caterpillar-tracked vehicle would not be surpassed until World War 2. In 1910, Hornsbys sold four caterpillar tractors to the War Office - driving the first from Grantham to Aldershot. The tractors were used for towing artillery. Unfortunately, the officers in the Royal Artillery were not enamoured with the vehicle, finding it noisy and slow. One officer wrote, The team of eight horses in my opinion is far superior under every condition.
Hornsbys thought civilian applications of the caterpillar track would be popular, but they only ended up selling one vehicle. Holt Manufacturing and C.L. Best Tractor Co. (the originator was Daniel Best) of the USA recognised its potential and sold many tracked vehicles; their vehicles were steered by a front wheel, unlike modern tanks. Hornsbys, with no incentives from military orders, did not see the same glowing future for the type of vehicle. They sold the patent to Holt, and only a year later, the British Army ordered 442 of Holt's caterpillar tracked vehicles made under licence by Ruston in Lincoln.
