Abstract: A brake (10) capable of functioning as a disk brake and parking brake having engaged and disengaged modes of operation comprising: a piston rod (30) movable with the disk brake piston (14) having a threaded portion (40), a nut (60) rotatably movable on the threaded portion (40) relative to a first stop (52); a pressurizing device (80, 82, 84; 92) for pressurizing the fluid chamber (20) to move the piston (14) and piston rod (30) to respective engaged positions, and a motor (66, 68) for rotating the nut (60) in one of a) synchronism with pressurizing the fluid chamber and b) subsequent thereto so that the nut moves along the threaded portion (40) into a contracting position with the first stop (52) for preventing the piston rod (30) from moving from its engaged position to achieve the parking brake function.

Abstract: A variable rate shock absorber having the interior of a working cylinder divided by a piston into an upper and lower working chamber. The lower working chamber is connected to a reservoir by a bi-directional valve member. A solenoid valve housed in a hollow piston rod has an actuated state connecting the upper working chamber to the reservoir. The output of the solenoid valve is connected to the reservoir by means of an axially disposed telescoping cylinder passing through the piston and the bi-directional valve member.

Abstract: A speed-responsive tag axle control system is disclosed including a comparison circuit which is operable when the rotational velocity of one driven wheel of a motor vehicle overruns the opposite driven wheel by a predetermined amount to simultaneously brake the faster driven wheel and shift the vehicle load from the tag axle wheels to the driven wheels. In one embodiment, a pressure fluid motor is connected between the tag axle and the vehicle chassis for normally transferring load from the driven wheels to the non-driven tag axle wheels, said motor being vented by said comparison circuit means to transfer the load back to the driven wheels upon the occurrence of a driven wheel overspin condition.