Abstract: A spring brake actuator has a quick release clutch for deactivating the brake in absence of fluid pressure and a governing device operating the clutch in response to the relative pressures prevailing at the service brake and spring brake cylinders. The governing device comprises a biased pilot valve and a signal valve which permit alternate operation of the brake release clutch manually or automatically.

Abstract: A lock actuator attachment for a pneumatic service brake has a spindle follower for the service brake piston. A freely rotating nut is threaded on the spindle and a brake for preventing nut rotation is operated by a piston that may be pneumatically or hydraulically operated to hold the service brake in actuated position.

Abstract: A spring brake actuator has manual means for discontinuing and automatic means for restoring the spring braking function. A non-self-locking nut member is rotatable about the spindle and is releasably locked to the brake cylinder in that direction it rotates due to spring force.

Abstract: A fluid pressure piston operated parking spring brake mechanism is coupled at the junction of a service brake actuator and slack adjuster by a pull rod linkage to apply brakes with the spring force. A disengagement mechanism permits return movement of the actuator when spring brake fluid pressure is vented.

Abstract: A force limiting device for a parking brake actuator is arranged in series with a service brake actuator to limit the maximum force of the two actuators to the maximum force from one of them. One actuator works from hydraulic pressure and the other from air pressure. Thus, an overflow valve controls the hydraulic pressure and is forced closed by an adjustable spring and open by either hydraulic pressure in a valve chamber or by air pressure exerted on a valve plunger. Both sides of the valve are maintained at the hydraulic pressure while the valve outlet is both closed or open.

Abstract: A manual disconnecting device is provided for disengaging the brake push rod in a spring brake actuator having a movable piston holding the spring compressed by fluid pressure during normal operation. The device once manually disconnected is automatically reconnected upon a normal spring compression stroke of the piston. The disconnecting device provides a clutching device between the piston and the push rod engaging a nut threaded on the push rod with non-self-locking threads. In one embodiment the nut is journalled in the piston. In another embodiment there are clutch surfaces on both the piston and nut which are disengaged by a rotary motion from a special tool.

Abstract: A brake adjuster mechanism is of the type operable by a piston moving a threaded spindle axially during braking with a threaded nut thereon adjusting the spindle position. Two control members movable with the spindle are held apart by a spring between shoulder stops on the nut and they serve to position the nut between two opposed clutch surfaces to permit nut rotation until a predetermined slack setting is achieved.

Abstract: The brake block has incorporated means such as strain gauges for measuring dynamic brake forces in two normal coordinate directions.

Abstract: A change-over valve controls a source of fluid under pressure to signal at an outlet line one of two different pressures in response to applied forces such as load on a vehicle. The valve has a rotary lever load application arm receiving the applied forces to rotate it against the force of a return spring. In unloaded condition the return spring vents the outlet line to atmospheric pressure. A spring loaded valve controls the fluid pressure path to the outlet line and is operated as the applied load force increases to provide fluid under pressure to the outlet line.

Abstract: A fluid pressure brake unit with a fluid piston actuated wedge that moves a brake push rod in a direction perpendicular to the piston stroke has provided therein a forked wedge astraddle the push rod that engages on opposed wedge surfaces respectively two rollers placed on opposite sides of the push rod and two rollers affixed to the brake unit housing. For hand brake use, a rotatable member has a cam head engaging the push rod assembly to move it independently of the wedge action.

Abstract: An actuator for a spring brake used for parking and emergency has a spring operating on the brake push rod which will apply braking unless fluid pressure in the braking system applied to a piston overcomes spring pressure. To disable the spring brake the rod is retracted by a mechanism coupling the piston to the rod so that the brake is automatically restored into service when the piston is operated by the fluid pressure. The mechanism has a one-way clutch engaging a threaded push rod by means of a nut in non-self-locking engagement on the push rod threads.

Abstract: A manual disconnecting device is provided for disengaging the brake push rod in a spring brake actuator having a movable piston holding the spring compressed by fluid pressure during normal operation. The device once manually disconnected is automatically reconnected upon a normal spring compression stroke of the piston. The disconnecting device provides a clutching device between the piston and the push rod engaging a nut threaded on the push rod with non-self-locking threads. In one embodiment the nut us journalled in the piston. In another embodiment there are clutch surfaces on both the piston and nut which are disengaged by a rotary motion from a special tool.

Abstract: A spring brake actuator has a fluid actuated piston coupled to the brake applying piston rod through a manually disconnectable conveying mechanism which enables the piston rod to return alone and which thereafter returns automatically to a position for conveying the piston rod in response to the piston movement.

Abstract: A single acting pneumatic brake assembly is constructed to permit the push rod to be returned by external force when brakes are replaced, and the like. Thus, two pairs of clutch surfaces are both disengaged while the push rod is returned by pressure applied between a stationary part and a movable member of the assembly such as the push rod and wheel. A movable clutch member holds the clutch surfaces open during return of the push rod. A spring holds one clutch surface closed until overcome by pressure to return the push rod.