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 two solenoid pressure modulated ABS relay valve incorporates a quick release valve in the control air circuit to allow a majority of the air in the control cavity to escape directly to ambient. The orifice through the exhaust solenoid need only handle a relatively small volume of air upstream of the quick release valve, i.e., between the quick release diaphragm and the inlet solenoid seat.

Abstract: An adapter plate for a caliper disc brake assembly is attached to the inboard side of the axle flange of a vehicle axle housing. The adapter plate is generally C-shaped to allow mounting around the central region of the axle housing. The inboard positioning of the adapter plate allows mounting of larger brake calipers within a confined space. The caliper is connected to the axle housing by the adapter plate for the purpose of positioning the caliper relative to the rotor and resisting the torque developed by the action of the brake pads on the rotor. In order to adjust the lateral position of the caliper, the adapter plate, in one embodiment, has a pilot surface which allows the axle flange to be recessed within the adapter plate. In another embodiment, a secondary adapter plate bridges over the opening in the adapter plate to allow mounting of the adapter assembly to the entire bolt circle of the axle flange.

Abstract: An oil separator such as used in an air charging system includes a bypass assembly. During normal operation, airflow from an inlet to an outlet passes through the filter to remove oil and oil vapor from the compressed air. If a restriction or blockage occurs in the filter, as exhibited by a predetermined pressure differential across the filter, a bypass passage is opened to allow direct communication between the inlet and outlet ports. A spring defines the pressure responsive member that allows the filter to move away from the valve seat and establish communication between the inlet and outlet ports of the housing.

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 self-cleaning feature is provided for a trailer ABS modulator. Direct exhaust is provided through the piston or diaphragm to establish control line and control volume drain capabilities. This provides for moisture removal from the control line or control volume. Quick exhaust during normal service braking is also improved and, likewise, exhaust during the ABS mode is improved.

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 single piece metal clamp is provided for. The clamp includes an upper portion having a cylindrical section and a cross member section integrally connected through spaced apart left and right legs. The clamp also includes a lower portion having a base with a plurality of through holes. The upper portion and lower portion are integrally connected by a pair of spaced apart left and right legs, each leg having a corresponding right angle formed therein.

Abstract: An improved, air tight valve seat for a pneumatic brake system is achieved by using a plastic valve seat that is coined by the valve member. The valve member is a harder material, for example metal, than the thermo-plastic valve seat. The valve member is brought to an elevated temperature less than the melting point of the valve seat. The valve member engages the valve seat, coining the desired surface of the valve seat to conform it to the valve member. The heated valve member then remains in the valve assembly after coining.

Abstract: A testing system and method are provided for an electronically controlled braking system to determine whether the solenoids of each of the modulators are properly wired. According to the test, each modulator is tested in sequence. The exhaust solenoid of a modulator is actuated multiple times and the hold solenoid of a modulator is actuated once. Discrete signals will evidence whether the modulator solenoids have been properly wired.

Abstract: A modulator valve for an ABS system for heavy duty vehicles is disclosed. It uses non flow-through solenoid valve assemblies that simplify the machining and manufacturing costs associated with the present arrangement. This eliminates complex pilot passages and also achieves a quicker acting release of the brakes during normal service braking.

Abstract: A method and apparatus for monitoring the operation of vehicle brakes on a vehicle equipped with an electronic braking system as is commonly used to provide traction control (TC) and/or an anti-lock braking system (ABS). The speed at which a first wheel located on a first side of a vehicle rotates in relation to the speed at which a second wheel located on a second side of the vehicle rotates during particular braking events is examined. For each wheel, any difference or "error" in the rotation speed during the select braking events relative to the other side wheel is accumulated or integrated over a select duration until a threshold difference value is reached which indicates a malfunction at the subject wheel end. The accumulated difference is periodically adjusted to account for normal or acceptable levels of wheel speed variation.

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 cylinder is divided into two chambers by a wall to receive a pair of pistons. This reduces the stroke length and correspondingly reduces the linear speed of the piston. This leads to a reduced PV factor associated with degradation and wear of the piston rings. Moreover, the multi-cylinder arrangement provides the same performance in an oil-free compressor assembly without appreciably expanding dimensional constraints relative to known systems.

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.