Abstract: A powered brake system for vehicles including wheel brake cylinders, a pump powered hydraulic pressure source, a reservoir hydraulically connected to the pump powered hydraulic pressure source, a control valve interposed between the wheel brake cylinders and the pump powered hydraulic pressure source for controlling the fluid pressure to the wheel brake cylinders, a valve interposed between the reservoir and the control valve for connecting the wheel brake cylinders to either one of the reservoir and the control valve, and an orifice valve interposed between the control valve and the valve for slowly supplying the fluid pressure from the control valve to the valve just when the fluid pressure of the control valve reaches the point where the pressure is higher than that of the wheel brake cylinders.

Abstract: A combined emergency and handbrake system employs a friction brake actuator having a spring motor in addition to a hydraulic service motor. The spring motor is restrained from operation by a second hydraulic motor which is normally maintained at operating pressure. By venting the second motor, the spring motor applies the friction brake. This provides failsafe operation for the emergency system, and a positive handbrake system when the car is parked with a de-energized or uncoupled pressure source. The second fluid motor is normally pressurized by application of fluid pressure to the hydraulic service motor. The handbrake may therefore be released by cycling the service brake. This eliminates a need for a second hydraulic or pneumatic actuator for the emergency and handbrake system and assures the safe operation of the car by operation of the service brake before the parking brake can be released. A mechanical retraction device is also provided for special situations.

Abstract: The service and emergency braking system for use on articulated vehicles having service brakes actuated by air pressure and having emergency brakes held in a released condition by air pressure. The system includes valving which is responsive to a pressure differential between the fluid pressure level in the service line connecting the portions of the articulated vehicle and a reference pressure, so that the emergency brake control is vented during a service brake actuation to permit the emergency brakes to effect a brake application when the pressure of the service line drops below the reference pressure by a predetermined amount, thereby providing braking on all portions of the vehicle in an emergency braking situation when the service brake line interconnecting the portions of the vehicle has been broken or has been left disconnected.

Abstract: A fluid pressure braking system for an articulated vehicle. The system includes valving which senses a failure in the brake service line connection between the tractor and trailer portions of the vehicle. If a failure in the service line connection is detected, the valving closes communication between the tractor and trailer portions of the vehicle and causes actuation of the trailer emergency brakes. When the brakes of the vehicle are released, the valving automatically resets itself to release the trailer emergency brakes.

Abstract: An improved wheel lock prevention device for use in the brake system of motor vehicles. The device has a relay valve included in assembly with a motor vehicle operator controlled brake velve, a wheel brake cylinder and a source of pressurized air. The relay valve has a primary and secondary pressure side. The primary pressure side is connected to the brake valve and the secondary side is connected to the wheel brake cylinder. A short circuit connection between the primary and secondary pressure sides is provided with a control for effecting a balancing of the pressures on both the primary and secondary pressure sides after the pressure on both sides has been reduced from a peak value by a desired extent during application of the brake system.

Abstract: A change-over valve including a housing and a slide sealingly guided therein is provided for use with a two-line trailer brake system having two brake circuits. The slide is retained in a normal position, at which supply tubes leading to compressed air supply tanks for the brake circuits are closed, by a piston loaded with compressed air from a supply tube, but is manually movable to a maneuvering position, at which the brakes of the system are released. The slide is provided with two channels and two associated check valves arranged so that when the slide is in the normal position it closes the supply tubes leading to the compressed air supply tanks for the brake circuits and so that when the slide is in the maneuvering position it connects those supply tubes via its channels and the associated check valves to a common space, which is connected to one or more emergency brake chambers for emergency brake pistons of the trailer brake system.

Abstract: A release device adapted to be interposed in the air pressure line to an emergency brake actuator of the type which sets its brake by spring action if the pressure in the air pressure line should fail or should fall below a safe pressure; the release device including a main valve movable in response to pressure in the air pressure line to a first position communicating between the air pressure line and the emergency brake actuator; and, in absence of such pressure, is movable to a second position by air pressure from an auxiliary source such as a hand pump or, if needed, air from an available tire, wherein the inlet from the air pressure line is closed and air is supplied from such auxiliary source to the actuator so as to release its brake; the release device further including a bleed valve to insure against any back pressure on the main valve when the air pressure line is functioning.