Patent ID: 7870920

Claim:
A snowmobile comprising: a frame; a motor supported by the frame; an endless belt assembly supported by the frame and moveable between a first position and a second position, the endless belt assembly including a pair of laterally spaced apart, longitudinally extending lower rails having front and rear ends and a belt having an inner and outer surface, the belt including a plurality of projections extending inwardly from the inner surface, and a plurality of apertures extending therethrough; and a drive unit adapted to transmit power from the motor to the belt, the drive unit including a central shaft, at least one sprocket supported by the central shaft at a position between the pair of lower rails, and a cylindrical region, the central shaft defining a first axis, the sprocket including a plurality of circumferentially extending projections positioned around a perimeter of the sprocket, the projections adapted to engage the plurality of apertures in the belt, the sprocket defining a first diameter, the cylindrical region being defined by the first diameter and a laterally extending axis being coaxial with the first axis, the cylindrical region being intersected by the front ends of the lower rails and the sprocket being positioned between the laterally spaced apart lower rails when the endless belt assembly is in the first position, and the front ends of the lower rails being spaced apart from the cylindrical region when the endless belt assembly is in the second position.