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The eccentric engineer: endless railway wheels that crawled like a caterpillar

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This edition tells the story of the tortuous path of the continuous railway, finally finding its footing in the form of one of the most well-known military fighting machines.

In a time when it seems none of us are going anywhere, it might be interesting to look back on a time when travel horizons were just opening, but the ‘going’ remained decidedly ‘soft’.

The railway, and the self-​propelled railway engine, was perhaps the greatest engineering achievement of the 19th century, allowing fast, uninterrupted travel regardless (to some degree) of weather. Yet for those in whom the railway inspired a real wanderlust, there was one problem: a railway could only go where the rails go.

Of course, no true engineer could tolerate such a restriction and so, in 1831, Polish polymath Józef Maria Hoene-Wronski formulated an idea for a train that took its tracks with it. However, life was cruel to Wronski, and nearly all his work in mathematics, physics, law and economics was written off as the ravings of a madman, not helped by his own uncompromising and highly critical character. Later ages have been kinder to him, but sadly his self-railing train was going nowhere.

It fell to another polymath, Sir George Cayley, the first man to really comprehend the principles of flight, to take up the baton. His output was legendary and included self-righting lifeboats, seat belts and the forerunner of the internal combustion engine, one of which, rather alarmingly, ran on gunpowder. In the January 1826 Mechanical Magazine, he describes how his Universal Railway comprises “...two endless chains consisting of portions of railway so jointed that they form an inflexible right line when resting on the ground, but each capable of coiling round the fore and hind wheel on one side of the wagon...”

Of course, Cayley’s machine was horse-powered and, bearing in mind its weight, could only have limited application.

By 1832, textile manufacturer John Heathcote and his partner Josiah Parkes had harnessed their own continuous railway to a steam engine to form a 30-ton ploughing machine. Sadly, this ploughed straight into a marsh, and, unable to fund another machine, Heathcote and Parkes’ idea sank with it. It was not until 1846 that British engineer James Boydell found the answer to the financial problems: in war. His ‘Endless Railway Wheels’ consisted of flat boards loosely attached to each wheel which, as the wheel turned, spread the weight of the machine over the lowermost board. This proved invaluable for moving gun carriages in the Crimean war and Boydell’s patent was taken up by the Woolwich Arsenal and named ‘Dreadnought wheels’.

The Dreadnought wheel was not quite a continuous railway, despite Boydell’s claims. It would fall to agricultural engineer John Fowler in England, and later Fyodor Blinov in Russia, to patent a vehicle with toothed wheels and a jointed track.

As the 19th century ended, the development of the steam engine brought mechanised transport to the farm and the battlefield, but in both cases it was easier to place planks under ordinary wheels in difficult terrain, rather than take an iron road with you.

British agricultural machine maker Hornsby added the track steering clutch and gave the world the name ‘Caterpillar’ after a lowly soldier rechristened the unimaginatively named No.2 machine.  

The trials proved a great success with the Mechanical Transport Committee (MTC), and David Roberts, Hornsby’s managing director and chief engineer, received a £1,000 prize and a chance to demonstrate the machine to King Edward VII.

Later trials included a tracked trailer carrying a dummy gun, leading Major W E Donohue to suggest that a single tracked unit might make a devastating land weapon. Unfortunately Roberts never followed up on the idea, and the Royal Artillery poured cold water on his suggestions for mechanised transport on the battlefield, preferring to stick with horse teams. When the MTC petitioned the War Office for funds to buy a Hornsby tractor for evaluation, the request was refused.

Having made no money, Roberts sold his patents to the American Holt Manufacturing Company for £4,000. The assiduous Benjamin Holt, hearing of the nickname of the machines, quickly trademarked the name ‘Caterpillar’. Just three years later, the First World War broke out and the British Army was forced to buy Holt ‘Caterpillar’ tractor units and ship them from the US.

As for Donohue’s suggestion of a tracked self-propelled gun, that would have to wait for the British Navy to take up the story and develop their own ‘land ships’. Finally, the continuous railway would find firmer footing in the form of the tank.

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