Abstract: An endless track drive system includes a track and multiple shafts bearing outer flanges integrally secured proximate first and second ends of the shaft and a middle flange integrally secured to the shaft between the first and second outer flanges. A central wheel secures to the middle flange and engages the track. The central wheel is formed of first and second semi-circular sections combinable to form a circle. Each half section includes a rim made of polyurethane, or like polymer and a hub made of an ultra-high molecular weight (UHMW) polymer. The hub bears a plurality of projections extending radially outwardly and having a proximal portion secured to the hub and a distal portion forming an outermost portion of the hub. The distal portions are substantially larger in the circumferential direction than the proximal portion. The rim is molded around the plurality of projections.

Abstract: A snowmobile ski having improved turn stability. The ski includes a lower surface for sliding contact with snow, the lower surface being configured with at least one longitudinally extending, downwardly open groove having an internal cross-section dimension that diminishes rearwardly to thereby progressively constrict the groove. The groove is open forwardly to receive snow within it and is open rearwardly to enable snow to exit from the groove. Snow received within the groove becomes packed when such snow encounters the progressively constricted portions of the groove as the ski slides forwardly on a snowy surface.