When asked by Tsar Nicholas II to develop a vehicle that could travel at all speeds over deep snow, ice or roads covered with lightly packed snow - a vehicle that could leave the road without slowing down - French engineer Adolphe Kégresse came up with a novel solution. He would go on to replace the rear wheels with an endless track system, using a flexible rubber belt. That was in 1906, and he was the tender age of 27 at the time; seven years later Kégresse, believing that he had perfected the system, applied for a patent in his native France, but then the Bolshevik revolution spoiled his plans when he had to flee Russia. The concept of the half-track, however, wasn't exactly new. The Holt Manufacturing Company (later to become Caterpillar) had toyed with the idea in 1913, and the likes of Lombard and others had produced half-track machines from 1916. However, the Frenchman's way of doing things was altogether more refined and sophisticated and offered a unique combination of performance, ride and reliability. Moreover, unlike caterpillar tracks, his rubber band didn't tear up the surface of the road - and this would inevitably add to its versatility and usefulness. What's so clever about the Kégresse set-up is that it used a unique flexible track design with a proper suspension system to support the vehicle's weight. The bogie itself consisted of three subassemblies, namely the rubber track including the four road wheels, the suspension with its adjustable idler wheel, and the driving axle with its drive pulleys or sprockets.