Diagram Showing Adaptation to the 'Large-Wheeled Tractor' Idea
The genesis of the “large-wheeled tractor” was as follows: Trenches with a parados and parapet about 4 ft. high were being constructed by the enemy in Flanders. The engineers consulted by the Land Ship Committee gave it as their considered opinion that if these obstacles were to be crossed, a wheel of not less than 15 ft. diameter would be necessary. Machines with these gigantic wheels were actually ordered, but the wooden model that was knocked together as a preliminary at once convinced even its best friends that the design was fantastic, and that any machine of the kind would be little better than useless on account of its conspicuousness and vulnerability. However, the “big wheel” idea did not utterly die, for in the upturned snout of the Mark I. Tank we have, as it were, its “toe” preserved, the track turning sharply back at about axle level, instead of mounting uselessly skyward, as would have been the case had not the old wheel idea been supplanted by that of the sliding track.