Abstract: An electrical driver circuit for a cantilever solenoid valve includes first and second electrical switching devices for converting logical control input signals into respective control outputs. Third and fourth electrical switching devices are controlled as a function of the control output produced by the first switching device. Fifth and sixth electrical switching devices are controlled as a function of the control output produced by the second switching device. A voltage potential difference is created between a first electrically common point, defined between the third and fourth switching devices, and a second electrically common point, defined between the fifth and sixth switching devices, as a function of the logical signals received into the first and second switching devices.

Abstract: A proportional load transfer valve is disclosed to shift a predetermined ratio of approximately fifty percent (50%) of the weight on a tag axle to the drive axle. The load transfer valve acts in response to a pneumatic signal indicative of a traction event. The valve alters the ratio of supply port pressure associated with the air suspension bags of the drive axle that is forwarded to the delivery port associated with the air bag suspension assembly of the tag axle. As the weight imposed on the drive axle approaches a predetermined maximum, the load transfer valve transfers less weight so that the drive axle is not overloaded.

Abstract: A lightweight, non-metallic valve is preferably formed of molded plastic. The valve has an hour-glass configuration or enlarged recesses formed therein to reduce the overall mass of the assembly and provide increased sensitivity to low flow rates. Sealing O-rings are snap fit into grooves at opposite ends of the symmetrical assembly.

Abstract: A double check valve is integrally located in a spring brake chamber to reduce plumbing associated with a pneumatic brake system. Anti-compounding is provided by virtue of a bias pressure of approximately twenty to thirty psi between a pressure chamber of a service actuator and an operating chamber of a parking/emergency actuator. Likewise, vehicle roll-back is addressed since the transition from a service application to a park application assures that the service brakes are sufficiently applied until the spring brake becomes operative.

Abstract: A remote fault indicating unit (12) for an electronic system, such as a vehicle adaptive braking system, includes a series of visual indicators, such as light emitting diodes (50-59), on one surface of the housing and a computer serial port connector (13) for use when troubleshooting is done with a PC (18) equipped with the appropriate software. Each of the indicators (50-59) is activated in response to a predetermined malfunction sensed in the system, such as a defective speed sensor, defective modulator, or a defect in the electronic circuitry. The indicators (50-59) are reset with a switch (15) when the system is repaired. When the reset switch (15) is activated, all of the indicators (50-59) flash on and are then turned off. The reset switch (15) can also be activated for a longer period of time changing the ECU (14) configuration.

Abstract: A method and apparatus for graphically monitoring and controlling a vehicle anti-lock brake system is provided. Multiple types of graphical data concerning different aspects of the anti-lock brake system are simultaneously displayed to a technician. Output lights provided as a part of the vehicle anti-lock brake system are graphically emulated on a display terminal. Various vehicle anti-lock brake system components, such as a retarder relay, modulators, indicator lights, and the like, are controllable through a graphical user interface, and both the presence and location of anti-lock brake system faults is graphically indicated to a technician. The method and apparatus also include graphically displaying real-time or previously recorded wheel speed data for all or selected individual wheels connected to a vehicle anti-lock brake system, alone or in combination with other graphical data, and for saving real-time wheel speed data for subsequent review.

Abstract: An air dryer and reservoir assembly for providing compressed air from an air compressor (20) on a heavy motor vehicle which includes an air dryer (14) connected to receive compressed air from the air compressor (20) and a secondary reservoir (12), including an integral purge volume (34), for storing compressed air which passes through the air dryer (14), with the air dryer (14) and the secondary reservoir (12) being securely attached to a housing (16) to form an air dryer reservoir module (10). A primary reservoir (18) for storing compressed air from the air dryer (14) is located remote from the air dryer reservoir module (10). A pressure equalizing mechanism (57) is disposed between the primary reservoir (18) and the secondary reservoir (12) for keeping pressure in the two reservoirs (12,18) equal.

Abstract: An pneumatic system (10) for a tractor trailer truck (6) which increases compressed air flow to the trailer reservoir (52) whenever the tractor (7) is parked. This decreases the time it takes to charge the trailer reservoir (52) to a sufficient pressure to release the trailer brakes allowing the truck (6) to move. In normal over the road operation the trailer reservoir (52) is charged through a tractor protection control valve (14) which is mounted on the tractor dash. However when the tractor (7) is parked and a tractor park valve (12) which is mounted on the tractor dash is pulled out compressed air from the tractor secondary reservoir (42) is delivered with an increased flow rate to the trailer supply line (50). When the tractor park control valve (12) is pushed in releasing the tractor parking brake the trailer charging reverts back to charging through the dash mounted tractor protection control valve (14).

Abstract: An ABS modulator solenoid valve (10), having one electric solenoid (12), in which the valve control piston (14) has a passage (16) therethrough for balancing the pneumatic pressure on both ends (34, 36) of the control piston (14). One end (34) of the piston (14) is disposed in a closed piston chamber (32) while the other end (36) is positioned to contact and position a valve spool (40). The passage (16) extends between the ends (34, 36) of the piston (14). Piston (14) is biased by a spring (50) to a position within the piston chamber (32). When the solenoid (12) is de-energized the piston (14) remains in this position and variable air pressure, from an operator controlled brake valve (126), can be supplied through the valve (10) to a brake chamber (128) for operating the vehicle service brakes. During an ABS application the solenoid (12) is energized to overcome the inlet spring (50) bias and the piston (14) moves into engagement with the valve spool (40).

Abstract: A supervisory circuit for an anti-lock brake system (ABS) unit. The circuit includes an independent internal voltage reference source that provides power to the circuit components. The circuit also includes an external power source monitor powered by the internal voltage reference source which inhibits the ABS unit when an external power source voltage exceeds a predetermined level. The circuit also includes a system voltage monitor powered by the internal voltage reference source that inhibits the ABS unit when a system voltage deviates from predetermined system voltage parameters. The circuit also includes an electronic control unit (ECU) monitor powered by the internal voltage reference source that monitors a periodic signal generated by an ECU and that inhibits the ABS unit if an ECU timing signal deviates from a predetermined threshold level. The supervisory circuit helps to prevent spurious operation of ABS modulators due to race conditions.

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: In accordance with the teachings of the present invention, a wheel speed sensor signal conditioning circuit is provided for conditioning sensor output signals received from a variable reluctance wheel speed sensor. The conditioning circuit includes filtering circuitry and peak detecting circuitry that detects the positive and negative voltage peaks of a sensor output signal irrespective of the sensor output signal crossing a reference voltage level. When the sensor output signal exceeds a predetermined peak to peak voltage level, the peak detecting circuitry limits the amplitude of the output signal and forms a dynamic high pass filter. A comparator circuit is coupled to the peak detecting circuitry and outputs a first signal when the peak detecting circuitry detects a positive voltage peak and outputs a second signal when the peak detecting circuitry detects a negative voltage peak of the sensor output signal.

Abstract: An electronic interface custom integrated circuit which provides interfacing between micro-controller devices and field effect transistors in truck or car anti-lock braking systems for controlling solenoid valves to modulate the pressure in the brake chambers or brake cylinders. The interface circuit includes built-in diagnostic and safety features including fault protection interlock, safety interlocks, status indication outputs and a special purpose analog output for enhancing the performance of anti-lock braking system electronic control units.

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 desiccant type air dryer assembly having an integral purge volume with a body assembly and a removable desiccant cartridge. A retention bolt is provided in the body assembly which serves the two-fold function of retaining the cartridge and body assembly in an assembled condition as well as providing a flow passageway for air moving through the air dryer.

Abstract: A desiccant type air dryer for an air supply system for a motor vehicle brake system. The air dryer incorporates features for convenient mounting and dismounting of a desiccant cartridge to the air dryer body assembly. This connection is achieved through the use of an externally accessible through bolt which passes through the body assembly and engages a central threaded boss on the load plate of the desiccant cartridge. Interlocking engagement between the desiccant cartridge and body assembly prevent these parts from rotating relative to one another during mounting and dismounting of the cartridge. The desiccant cartridge is readily removed through engaging the through bolt driving head using conventional tools.

Abstract: An electronically controlled compressed air system (10) includes an air dryer (16) which dries compressed air before the compressed air is communicated to a reservoir (26). The air dryer (16) includes a desiccant (18) which is purged by using air stored in the reservoir (26). A pressure transducer (13) is installed on the reservoir (26) and transits an electrical signal, indicative of the pressure in the reservoir (26) to an electric controller (11). Electric controller (11) transmits signals at various selected pressure levels to solenoid value (28) to control loading and unloading of the compressor (12), to solenoid valve (36) to control purging of the air dryer (16), and to the warning light (40) to alert an operator of a low air pressure condition.

Abstract: An air supply system for a motor vehicle air brake system incorporating a desiccant type air dryer. The purge capacity of the air dryer is enhanced providing greater water and contaminant removable characteristics for the air dryer. The system incorporates a pressure reducing element and a control system for the system compressor causing air passing through the air dryer to be at a higher pressure than that necessary for charging the system reservoir. The higher pressure air supplied to the air dryer provides greater volumetric capacity for the purge volume of the air dryer. In this way an air dryer purge volume of a given size provides a greater purge capacity.