Abstract: A fluid pressure braking system for a vehicle equipped with a drive line retarder automatically reduces the braking pressure level communicated to the brakes controlling the driven wheels of the vehicle to adjust for the retardation effected by the retarder. The retarder is actuated automatically each time the brake is applied by calculating the appropriate retardation level as a function of the brake pressure being demanded by the vehicle operator and by the load carried by the vehicle.

Abstract: A fault indicating mechanism for an electronic system, such as a vehicle adaptive braking system, includes a series of visual indicators, such as light emitting diodes, on one surface of the housing within which the electronic components comprising the system are sealed. Each of the indicators 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. A magnetically responsive switch is sealed within the housing adjacent the indicators, but is not visible from the exterior of the housing. The indicators are reset when the system is repaired by the mechanic who holds a common magnet against the housing adjacent the switch. When the switch is activated by a magnet, all of the indicators flash on and are then turned off. A non-volatile RAM stores malfunctions sensed by the system when the system is powered down, so that all malfunctions are again indicated immediately when the system is powered up.

Abstract: A fluid pressure braking system includes pressure sensors in each of the supply and service reservoirs and in the supply line to the trailer. The system includes an air compressor which is loaded and unloaded in response to variations in the pressure level in the supply reservoir by actuation of a solenoid valve by an electronic control module which is responsive to the pressure sensors. The system includes spring brakes which are controlled by the control module through actuation of solenoid valves. The control module is similarly responsive to supply line pressure and the pressure level in the supply line to control a solenoid valve which controls communication through the supply line.

Abstract: An electronically controlled fluid pressure braking system for a heavy duty vehicle includes an operator controlled mechanism which generates independent brake pressure command signals, each of which are transmitted to separate auxiliary controllers. Each of the controllers transmits its command signal to the other auxiliary controllers and also to a master control unit. The master control unit sorts between the command signals and generates a preliminary brake pressure request signal which is transmitted back to each of the auxiliary controllers. Each of the auxiliary controllers then examines the brake pressure request signal received from the master controller and actuates the corresponding vehicle brakes if the pressure request signal is within normal limits. If the signal is not within normal limits, each of the auxiliary controllers is capable of generating a brake pressure request signal independently of the master control unit.