A method for estimating the pressure, i.e., pressure stroke, in a wheel brake cylinder, in particular in connection with a vehicle stability control system for calculating an effective control time, assignable to an instantaneous controller cycle, of an PWM-controlled valve actuating the wheel brake cylinder, on the basis of an actual control time definable by a control unit during the instantaneous controller cycle or an effective control time assignable to a preceding controller system and a valve stroke relative to a maximum stroke; and for calculating a pressure stroke of the wheel brake cylinder between two consecutive controller cycles, based on a valve pressure/volume characteristic retrievable from the control unit; an effective pressure difference across the valve; and the calculated effective control time.

A hydraulic braking apparatus for a motor vehicle having a service braking system (A) fed by a central hydraulic unit (3) and an emergency braking system (B). A simulator (M) resists a forward motion of an actuator member (D, 16) for a master cylinder (17) to define a reaction corresponding to the progress of a braking operation. Admission solenoid values (9a-9d) and exhaust solenoid values (14a-14d) connected to the wheel brakes (2a-2d) modulate pressurized fluid supplied by a central hydraulic unit (3) in effecting the braking operation. Sensors (8, 13a-13d, 24, 29) in the motor vehicle detect various braking parameters that are communicated to a computer (C) to control the solenoid valves (9a-9d; 14a-14d) such that the braking operation is a function of the travel of the actuator member (D, 16).

A fluid compensator is provided in a hydraulic control unit of vehicular brake system. The fluid compensator permits additional displacement of a master cylinder piston during anti-lock braking events only by storing fluid in the hydraulic control unit. The additional displacement moves a seal mounted on the master cylinder piston away from a compensator port orifice, thereby preventing repeated "nibbling" of the seal which can cause premature seal failure.

A hydraulic booster is provided between a M/C pressure and a W/C pressure. The hydraulic booster is composed of a pump and an amplifying piston amplifying the brake fluid amount discharged from the pump. The brake fluid discharged from the amplifying piston is supplied to the W/C via a first pipeline. The brake fluid discharged from the pump is supplied directly to the W/C via a second pipeline. First and a second control valves select the first or the second pipeline as a pressurizing path to the wheel cylinder.

A brake squeal attenuator for use with aircraft wheel brake assemblies. The attenuator includes a housing having a piston member and a weight disposed therein. The piston member and weight are biased by a spring disposed within the housing. The housing includes a neck portion which is in fluid communication with the hydraulic actuators of the brake assembly with which the attenuator is being used. The piston thus is biased on one side thereof by the biasing member and on an opposite side thereof by the hydraulic fluid pressure acting thereon. During braking, when torsional oscillations occur in the brake assembly which would otherwise cause objectionable brake squeal to occur, the entire housing of the attenuator, which is fixed to the housing of the wheel brake assembly, moves in accordance with the torsional oscillations which occur. The weight associated with the piston member causes movement of the piston member to lag behind movement of the attenuator housing as the attenuator begins oscillating. The attenuator thus produces a pumping of hydraulic fluid to and from the hydraulic actuators of the brake assembly which are timed to damp the torsional oscillating movement of the wheel assembly. The attenuator can be easily retrofitted to virtually all aircraft wheel brake systems without significantly adding to the cost or complexity of such systems.