Abstract: A device for providing a retarding force against the motion of a vehicle, which device does not intrude upon the engine, is not dependent upon the vehicle gear selected, and does not exhibit fade or skid characteristics. A multiple plate clutch engages the drive train of the vehicle with a compressor assembly. A three speed gear assembly is operatively connected between the multiple plate clutch and the providing modulation of the ratio of speed between the aerodynamic rotor and the drive train. A throttle valve governs the fluid mass flow through the rotor of the compressor assembly providing precise modulation of retarding torque exerted by the rotor. The device may also be adapted for other types of machines and motors having rotating shafts upon which it is desired to apply a retarding torque.

Abstract: A device for providing a variable retarding torque upon a rotating shaft includes an aerodynamic rotor and control means which is responsive to independent and external signals to continuously vary the ratio of the speed of the aerodynamic rotor as compared to the speed of the rotating shaft. The control means includes a multiple disc, dynamic, torque limiting friction clutch which is operable to vary the torque transferred between the rotating shaft and the rotor. Modulation of the dynamic clutch may be done at any time during active operation of the device.

Abstract: A device for providing a retarding force against the motion of a vehicle, which device does not intrude upon the engine, is not dependent upon the gear selected, and does not exhibit fade or skid characteristics. A torque limit clutch engages a ground engaging wheel of the vehicle with a first aerodynamic rotor. In one embodiment, the ratio of the speed of the aerodynamic rotor as compared to the speed of the ground engaging wheel is controlled by a serially connected variable-ratio gearbox. In another embodiment, the ratio is controlled by an epicyclic gear train, a second aerodynamic rotor and a pump.