Abstract: An improved relay valve (10) having a supply port (16), a delivery port (18), an exhaust port (20), a control port (17), a relay piston (14) controlling communication between the supply port (16), the delivery port (18), and the exhaust port (20) in response to a pneumatic signal applied to the control port (17) and including a passage (40) extending through the piston (14) to the exhaust port (20) for draining to atmosphere moisture and other contaminants which build up on the top of the piston (14). A diaphragm element (30) having a cylindrical protrusion portion (36) is disposed in the piston (14) above the passage (40) to act as a check valve and seal the passage (40) when a pneumatic signal is applied to control port (17). The diaphragm element includes a top resilient portion (32) which serves as a spring to open the drain passage when no signal is applied to control port (17).

Abstract: A pilot operated relay valve (10) for an air pressure braking system includes a relay piston (16) which is responsive to the pressure at a control port (20) to open the valve (10) so that it's inlet port (38) is in free communication with it's outlet port (24). The relay piston (16) includes a balance orifice (26) which permits the outlet port (24) to communicate with the control port (20) to equalized or balance the pressure differential therebetween. A shut off valve arrangement (80,82) or a check value (90 or 92) is provided to shutoff or control flow through the balance orifice during rapid release modulation of the pressure signal for braking applied to the control port (20).

Abstract: A compressed air system includes an air dryer which dries compressed air before the compressed air is communicated to a reservoir. The air dryer includes a desiccant which is purged by using air stored in the reservoir. A pressure reference purge control valve is installed between the air dryer and the reservoir and includes a housing which defines a pressure reference volume. A pressure which is a function of the highest pressure level communicated to the reservoir is trapped in the reference volume. The valve permits purging only until a pressure is reached which is a predetermined pressure drop below the reference pressure level, whereupon purging is terminated.

Abstract: A signal generator for generating an electrical signal which varies in accordance with movement of an actuating member includes a plunger slidable mounted within a housing which carries a pair of permanent magnets for generating a magnetic field to be applied to a hall effect generator. As the plunger is moved relative to the hall effect generator, the magnets are also moved relative to the hall effect generator, thereby varying the magnetic field applied thereto. Accordingly, a variable output signal is generated as a function of the position of the input member.

Abstract: A signal generator for generating an electrical signal which varies in accordance with movement of an actuating member includes a plunger slidable mounted within a housing which carries a pair of permanent magnets for generating a magnetic field to be applied to a hall effect generator. As the plunger is moved relative to the hall effect generator, the magnets are also moved relative to the hall effect generator, thereby varying the magnetic field applied thereto. Accordingly, a variable output signal is generated as a function of the position of the input member.

Abstract: A relay valve for a fluid pressure braking system includes a relay piston and a load piston which is responsive to the pressure at the inlet port of the relay valve to exert a biasing force on the relay piston loading the latter against the inlet/exhaust valve. The biasing force is opposed by fluid pressure at the inlet port acting across the effective area of the inlet/exhaust valve. The biasing force is greater than the spring force holding the inlet/exhaust valve closed, so that the valve responds immediately to pressure signals transmitted through the control port of the relay valve.

Abstract: A valve assembly includes a housing and a valve plunger slidably mounted within the housing, which carries a pair of valve engaging, ringlike elements for engagement with corresponding seats on the plunger. The cross-sectional diameter of one of the ringlike valve elements is substantially greater than the other, and fits on the plunger with clearance to permit it to be deformed and deflected relative to the plunger to assure a proper sealing engagement of the other ringlike element. A collar retains the other ringlike element, and acts against the valve seat to limit movement of the plunger relative to the housing.

Abstract: A control valve for a vehicle parking brake system is controlled by a pair of camming mechanisms, one of which is controlled by the shift lever of the vehicle automatic transmission and the other of which is controlled by a manual control knob in the vehicle operator's compartment. Camming mechanisms control the valve such that the parking brakes on the vehicle are always applied when the shift lever is disposed in the "Park" position, but the vehicle parking brakes can be applied or released manually by manipulation of the control knob when the shift lever is placed in one of the other positions other than the "Park" position along the shift quandrant of the automatic transmission.

Abstract: A hydraulic control valve for controlling the parking brakes of a vehicle hydraulic braking system having mechanically applied parking brakes which are released by hydraulic pressure includes a housing having a mechanically actuated control valve and a diverter assembly. When the vehicle is parked, the parking brakes are vented to reservoir and fluid from the vehicle hydraulic pump is communicated directly from the inlet of the valve to the return or drain port of the valve. When the brakes are released, communication between the spring brakes and reservoir pressure is cut off, and fluid communicated into the inlet is diverted to the diverter assembly, which builds pressure to a predetermined level which is communicated to the vehicle parking brakes to release the latter. When the predetermined pressure level is attained, the diverter assembly automatically opens to permit fluid to bypass the diverter assembly back to the return or drain port.

Abstract: A system for activating and de-activating a packing brake using only motion of the transmission gear shift lever. A mechanical linkage from the gear shift lever controlling the position of the cam. The cam in turn controls the position of a valve which can connect the spring-activated hydraulically deactivated parking brake to a source of pressurized fluid, or drain the brake. The cam is precisely positioned relative to the valve by a cam support structure, and the entire valve and cam mechanism preferably is mounted on the steering column near the gear shift mechanism. The preferred method for installing the apparatus in proper adjustment also is disclosed.

Abstract: A knob and shaft assembly for operating, for example, a vehicle air brake control valve includes a knob member having a front face and a barrel projecting the face, and a shaft member which is threadedly engaged with the threads carried on the circumferentially extending wall defining cavity within the barrel. The assembly is provided with locking detents comprising protrusions on the shaft which are received within apertures on the barrel to releasably lock the knob member to the shaft member, thereby preventing the members from being accidentally becoming disengaged, and also assuring the proper orientation of the knob with respect to the shaft to permit indicia embossed on the knob member to be easily read by the operator.

Abstract: A dual circuit brake valve is provided with a delivery differential control mechanism which controls the differential between the delivery pressures of the primary and secondary braking circuits. The delivery differential control mechanism includes a spring retainer which is mounted on the end of the stem of the relay valve and which receives a spring-biased plunger. The plunger engages with the actuating member during the brake application to thereby transfer the force of the spring to the relay member and therefore to the valve members of the secondary circuit. This transfer of the spring force reduces the crack open pressure of the valve members controlling communication through the secondary circuit, to thereby reduce the differential between the pressures generated and the primary and secondary circuits.

Abstract: A dual circuit brake valve includes a plunger assembly carrying the primary valve seat, and the primary valve plunger within the primary piston. A pair of axially-spaced, circumferentially extending bearing members extend from the primary piston slidably engaging larger and smaller diameter portions of the bore of the housing to thereby guide the primary piston independently of other components within the housing. The secondary set of valve actuating members is actuated by a relay piston which is similarly guided in larger and smaller diameters of the bore independently of other components within the valve housing. The primary piston defines a pressure effective area due to the difference in the larger and smaller portions, so that inlet port pressure acting on the effective area yieldably urges the plunger toward the brake released position.

Abstract: A clutch drive (10) includes a spindle (16) mounting a driving member (94) and a driven member (126) for rotation about the spindle (16). The driving member (94) includes a pressure plate (96) which moves axially along the spindle (16) to engage and disengage from the driven member (122). Disengagement of the pressure plate (96) is effected by a piston and cylinder mechanism (34, 52) operated by compressed air. A plurality of circumferentially spaced springs (106) yieldably urge the pressure plate (96) into engagement with the driven member (126). A drive link (112) interconnects adjacent springs (106) to form a link through which driving torques are transmitted. The drive link (112) is curved, so that shock loads created upon engagement of the clutch are absorbed by straightening the drive link (112).