A drive apparatus for a concentrator photovoltaic array including a gearbox case, a motor body housed within the gearbox case and a motor shaft coupled to and extending though a motor bearing of the motor body and having an axis of rotation. A front shaft mount bearing is coupled to one distal end of the motor shaft and a rear shaft mount bearing coupled to the other distal end of the motor shaft, and the front and rear shaft mount bearings are constrained by the gearbox case. A driver gear can be coupled to the motor shaft to drive the photovoltaic array. The front and rear shaft mount bearings transfer loads from the motor bearing to the gearbox case.