Suspension system for vehicles

A tractor (100) has sprung left and right rear suspensions, each suspension including a suspension arm (106,104) pivotally coupled to the tractor chassis (102) to pivot about a pivot point (134). A planetary gear system (120',120) is fixed to the suspension arm (106,104) having a sun gear (502,602,702) driven by the engine and a planetary gear carrier (510,610,710) that is coupled to and drives an axle (500,600,700) supporting a rear wheel(108,110). The ring gear (518,617,712) is fixed with respect to the suspension arm (106,104).