Abstract: There is disclosed a hydrostatic motor provided with radially arranged hydraulic cylinders provided with radial pistons composed of pairs of pistons with different diameters fitted one into the other. The motor is selectively operable in either of two operating conditions, in a first of which the large and small pistons move as a unit in a heavy duty operation, and in a second of which only the small pistons move in a low duty operation. The motor includes a rotor and a stator, duct means arranged in the stator for the supply of pressure fluid to the pistons, a change-over unit within the motor, and a fluid distributor unit housed in the stator. The motor of the invention employs virtually the same distributing circuits during its operation in both its heavy duty and its low duty modes of operation.

Abstract: A pressure system for driving the wheels of a vehicle in which the wheel driving motors are arranged in pairs on opposite sides of the vehicle comprising a duplex pump assembly composed of two pumps connected in parallel and coupled in open circuit with a respective pair of wheel driving motors. A flow divider is provided in each circuit for dividing the pressure fluid delivered by the respective pump to the wheel driving motors of the associated pair.