The tank was fitted with two pairs of caterpillar tracks. The outer tracks resembled those of the Mark I, but were flatter and 61 centimetres wide, while a pair of additional, narrower tracks were fitted to the underside approximately 6 inches higher than the main tracks. They were not intended to be used for normal driving but were to be engaged to give extra traction over rough ground and would have helped to prevent "bellying", i.e. the tank becoming stuck on higher ground between the two outer tracks. All four tracks could be simultaneously driven by two Daimler 105 horsepower (78 kilowatt) engines, positioned on the centre-line, with the inner tracks connected to the main units via dog clutches. Each engine had its own primary gearbox, both of which drove into one single differential. This differential powered two secondary gearboxes, one for each main track. This differs from the solution chosen for the later Whippet in which each engine drove its own track.