Abstract: An electrical circuit for selectively operating a vehicle parking brake (16) with the energizing and de-energizing of a coil (50) of a solenoid valve (30) in response to an operator input. The electrical circuit comprising a source of electrical energy (V Bat), an operator actuable switch (47) connected by line (59) to the coil (50) and a first microprocessor (49) which in turn is connected by an electronically controllable switch (45) through a low side driver (51) to connect line (57) from coil (50) with a ground (55) and a second microprocessor (53) connected to the first microprocessor (49) and electronically controllable switch (45) for detecting erroneous first microprocessor (49) operation.

Abstract: A hydraulic brake system wherein a portion of a volume of a first fluid supplied to a steering system by a pump is selectively diverted to an actuator assembly for a master cylinder to develop an force for actuating a master cylinder to pressurize fluid which is supplied to wheel brakes. An electronic control unit (ECU) for the brake system receives a first input signal indicative of the flow of fluid from the pump in the steering system, a second input signal indicative of the input force applied by the operator and a third input signal indicative of the speed of the wheels of the vehicle for developing a pulse modulated operational signal. The electronic control develops an operational signal which is supplied as the pulse modulated operational signal to a magnetic responsive valve. The pulse modulated operational signal creates a variable orifice in the magnetic responsive valve to restrict the flow of the first fluid to the steering gear and increases the fluid pressure of the first fluid.

Abstract: A secondary source of braking for large hydraulically braked vehicles utilizing the available power source (38) provided by typically available anti-skid and traction control braking systems. The anti-skid braking system is used to control the secondary braiding function in a manner optimal to the operating condition of the vehicle. Unique distinctive operating modes are used when the vehicle is either moving (79, 81, 83), or stationary (57, 59, 73). The advantages of the stationary mode are fast time response and high output pressure controlled with a minimum of pump operation and fluid movement. The advantages of the dynamic mode are the ability to modulate brake pressure in response to the driver's command.

Abstract: A brake system (10) having a control member (12) through which a remotely located master cylinder (18) is selectively supplied with either a first operational fluid developed by a first pump (14), a second operational fluid developed by a second pump arrangement (500,600) or a third operational fluid from a storage system (302) as a function of a brake force applied to an input push rod (16) and a sensed flow of operational fluid through a shuttle valve (64) to the master cylinder for effecting a desired brake application. A electronic control unit (200) receives an input signal corresponding to the brake force and a sensed flow to activate the second pump arrangement (500,600). Whenever the fluid pressure of the first operational fluid is insufficient, the second pump is activated and the second operational fluid supplants the operation of the master cylinder (18) by the first operational fluid to effect the desired brake application.

Abstract: A secondary source of braking for large hydraulically braked vehicles utilizing the available power source (38) provided by typically available anti-skid and traction control braking systems. The anti-skid braking system is used to control the secondary braking function in a manner optimal to the operating condition of the vehicle. Unique distinctive operating modes are used when the vehicle is either moving (79, 81, 83), or stationary (57, 59, 73). The advantages of the stationary mode are fast time response and high output pressure controlled with a minimum of pump operation and fluid movement. The advantages of the dynamic mode are the ability to modulate brake pressure in response to the driver's command.

Abstract: A secondary source of braking for large hydraulically braked vehicles utilizing the available power source (38) provided by typically available anti-skid and traction control braking systems. The invention improves the time response of a secondary braking traction control system by utilizing stored fluid in the low pressure anti-skid braking system accumulators (34) to provide for faster build of pressure by the pump motor (38). Fluid is stored and utilized based on vehicle behavior and operational states and is based upon the principal the traction control, anti-skid braking and secondary braking requirements are generally mutually exclusive. This allows for a decreased response time of the secondary braking system and also provides for improved initial cycle response of typical traction control events that utilize the system configuration.