Abstract: A hybrid electric drive system is described that includes a heat engine having a drive shaft, and two electric motor/generators having rotors that are coaxially connected to the drive shaft. A control arrangement for these elements is also described that provides a relatively simple combined operation for driving a vehicle.

Abstract: A vehicle having a traction apparatus which can be removably attached to the vehicle when the drive wheels thereof have been removed. The apparatus comprises a pair of endless, flexible tracks carried by a number of bogie wheels supported by elongated beam-like members with each track having means for making a driving connection between the adjacent drive axle of the vehicle. The apparatus is suitable for connection to the rear axle of a vehicle and the forward end of the apparatus is provided with means for locking the apparatus in place when the rear end of the apparatus is connected to the vehicle.