Abstract: In an anti-skid control apparatus for a four-wheeled vehicle, fluid pressure control valve devices are arranged in the respective brake conduits, and a control unit determines which side of the road has a lower coefficient of friction. This side is called the low side. The fluid pressure control valve device connected to the one front wheel on the low side effects brake relieving control on the basis of the brake relieving signal of the one of the front and rear wheels on the low side which has generated the brake relieving signal sooner than the other. In the alternative, it effects brake relieving control on the basis of the brake relieving signal of the one or ones of the front wheels on the low side of the rear wheels which has generated the brake relieving signal sooner than the other or others.

Abstract: For the purpose of optimizing the suction behavior of a pump in an anti-locking brake system in which the pressure acting on the wheel brakes is reducible by bleeding hydraulic fluid through a return line, with a hydraulic pump whose suction chamber is connected through a suction line to a hydraulic fluid reservoir, the return line is connected to the suction chamber, a hydraulic link existing simultaneously between the return line and the suction line and a release valve and/or a reserve volume cylinder is inserted in the return line upstream of the point of connection between return line and suction line.

Abstract: The present invention provides an apparatus and method of utilization thereof of a vehicle brake master cylinder proportioning valve. The valve includes a valve body having a main bore fluidly connected with the master cylinder, primary and secondary circuits. A first housing fluidly seals the main bore into first and second chambers. A second housing fluidly separates the main bore second chamber from the secondary circuit. A valve piston spring biased away from the first chamber is mounted within a bore of the housing. The valve also has fluid communication between the second circuit and second chamber when the fluid pressure within the second circuit exceeds the fluid pressure within the second chamber. At an increase in master cylinder pressure past a first predetermined pressure the valve piston moves towards the first chamber, reaching a pressure balanced position metering pressurized fluid flow from the master cylinder to the second circuit.

Abstract: An anti-lock brake system (ABS) for a road vehicle is equipped with a wheel slip control system (ASR) and a hydraulic dual circuit brake system having front axle/rear axle brake static brake circuits, one brake circuit being allocated to the driven (rear) wheels of the vehicle and one to the non-driven (front) wheels. The system has two high-pressure pumps, one for each of the two brake circuits and which, in control phases of the ABS, brake fluid can be fed into the output pressure spaces of the brake unit and wherein the high-pressure pump allocated to the rear axle brake circuit is also utilized as auxiliary pressure source for the ASR. At the front axle brake circuit, the ABS operates on the feedback principle and at the rear axle brake circuit it operates on the discharge principle.

Abstract: Control system for controlling an anti-lock braking system having a brake for a wheel of a motor vehicle, wherein a skidding or locking condition of the wheel is detected by a detector based on a running condition of the vehicle and a rotating condition of the wheel, and a slip ratio of the vehicle is maintained within an optimum range by a pressure-regulating device, by increasing, decreasing and holding a brake fluid pressure applied to the brake, in response to the detected locking condition of the wheel. A predetermined pressure-decrease time during which the fluid pressure is decreased is measured by a measuring device, and a deceleration rate of a rotating speed of the wheel when the pressure-decrease time has elapsed is detected by a detecting device. A device is provided for determining an extension time during which the fluid pressure is further decreased, such that the extension time increases with the detected deceleration rate of the wheel.

Abstract: An antiskid apparatus including a changeover valve disposed in a line connecting a master cylinder and a wheel brake, the changeover valve being changed over between a first mode for cutting off the wheel brake from the master cylinder and connecting the wheel brake to a reservoir, and a second mode for alternately connecting the wheel brake to a pump and the reservoir when an antiskid operation is performed, a pressure increase control valve connected between the pump and changeover valve with wheel brake pressure serving as a control signal pressure, and a pressure decrease control valve connected between the wheel brake and reservoir with wheel brake pressure serving as a control signal pressure. The pressure increase control valve decreases an amount of pressurized oil flow from the pump to the wheel brake when wheel brake pressure decreases and increases the amount of pressurized oil flow from the pump when wheel brake pressure increases.

Abstract: In a brake pressure control system provided with a discharge valve in its discharge line for the control fluid from a control chamber, the discharge valve having an on-off valve for opening and closing the discharge line so that when the discharge valve is opened, the control fluid pressure in the control chamber will be lowered to reduce directly or indirectly the braking force on the vehicle, the present invention provides a system having a second discharge valve arranged in series in the discharge line. With this system, even if one of the valves should fail to close the discharge line, the other valve will act to prevent the leakage of the control fluid pressure in the control chamber.

Abstract: A control valve for an anti-lock brake system includes a one-piece valve body having an inlet opening in one end and an outlet opening in an opposite end. The valve body is provided with four other openings extending into the body and defining separate associated chambers for respectively receiving an isolation valve assembly, a pressure differential switch assembly, a dump valve assembly and an accumulator assembly. The inlet, outlet, and the four internal chambers are connected by appropriate internal passageways. The control valve is used to selectively hold, dump, or reapply brake fluid pressure to selected wheel brakes to prevent lock-up of the associated wheels.

Abstract: An automatic drive slip regulating unit for motor vehicles or the like which communicates via a connecting line with at least one brake line between a master brake cylinder and an anti-skid system with wheel brakes connected downstream. The connecting line is intended to discharge into a cylindrical chamber of an additional master cylinder, and the cylindrical chamber is intended to be variable by a plunger that is subject to the pressure of a spring-supported spring reservoir plunger. To return this spring reservoir plunger to its terminal position, for instance in the event of leakage or upon termination of the drive slip regulation, the spring reservoir plunger is to be subjectable on its other side to a pressure medium which derives from a separate low-pressure hydraulic circuit.

Abstract: The brake control system for use in a vehicle includes a compression cylinder device, which communicates with a fluid passage between a gate valve and a wheel cylinder. A compression piston is reciprocately disposed inside of the compression cylinder device. A cut off valve member is disposed in the compression cylinder device, which closes a fluid supply passage between a fluid chamber of the compression cylinder device and the wheel cylinder of the brake device for the driven wheel. The system further includes a valve system provided between an accumulator and the compression cylinder device. The valve system is provided for selectively supplying the brake fluid pressure in the accumulator to the compression cylinder device during the lock-preventing and acceleration slip-preventing controls.

Abstract: The present invention concerns a vehicle anti-lock brake control system which does not require the use of an auxiliary hydraulic pump and, in the preferred embodiment, is adapted to control only the rear brakes of a four-wheel vehicle. The control system includes a normally open solenoid actuated isolation valve connected between the master cylinder and the rear wheel brakes, and a normally closed solenoid actuated dump valve connected between the rear wheel brakes and a fluid accumulator. A computer control is connected to monitor the rear wheel speed and deceleration and, during breaking of the vehicle, functions to control the application of hydraulic pressure to the rear brakes via the isolation and dump valves in order to prevent lock-up of the brakes. In the event excessive rear wheel deceleration is detected during a vehicle stop, the computer control closes the isolation valve to hold pressure to the rear brakes at a relatively constant level.

Abstract: An antiskid apparatus provided in a communicating passage extending between a master cylinder and a brake cylinder in a brake system for a vehicle includes a flow rate control valve provided in a discharge passage which connects a pressure regulating chamber and a damping valve. The flow rate control valve includes a valve body having a flow path which defines a part of the discharge passage, and a valve member disposed in such a manner as to be reciprocal along the flow path. The valve member is normally separated from a valve seat formed on the valve body by the action of a spring in order to open the flow path. When subjected to pressure supplied from the pressure regulating chamber, the valve member is brought into contact with the valve seat to close the flow path. The valve member is provided with an orifice which provides communication between the flow path and a portion of the discharge passage on the side thereof which is closer to the pressure regulating chamber.

Abstract: An antiskid control system wherein the conventional method of performing an opening/closing change-over operation by a pulse train signal on a electromagnetic valve for increasing hydraulic braking pressure at a variable rate of increase is not employed but the pressure increasing rate is arranged to be variable by the use of an electromagnetic valve having some throttled position.

Abstract: In an anti-skid control system for motor vehicles of the type that the drive system thereof is switchable between two-wheel drive (2WD) and four wheel drive (4WD), the design is made such that when the drive system of the motor vehicle is switched, the anti-skid control system is changed such that under 2WD condition, it operates as a three-channel system wherein the front wheels of the motor vehicle are controlled independently and the rear wheels thereof are controlled on the basis of the lower one of the rear wheel speeds, while under 4WD condition, the anti-skid control system operates as cross or X-type two channel system wherein the wheels associated with each of the two channels are controlled on the basis of the lower one of the two wheel speeds.

Abstract: A control valve assembly for use in an anti-lock braking system wherein a 3-way isolation valve normally connects a wheel cylinder to a master cylinder and isolates that wheel cylinder(s) from the master cylinder and simultaneously connects the wheel cylinder to the common connection of a pressure modulating unit when the anti-lock system has been energized. The assembly enables use of a three channel anti-lock system in a dual circuit cross split brake system and increases the protection of the normal brake circuit from leakage in the modulating unit.

Abstract: A vehicle antilock braking system comprises a servo for varying the effort applied by a brake on a wheel of the vehicle, a valve being provided to selectively connect the servo to a source of relatively high pressure or a source of relatively low pressure, via passageways of relatively high or relatively low restriction, so that the servo may be controlled to reduce or reapply braking effort at relatively slow or fast rates, depending on the acceleration or deceleration of the wheel.

Abstract: A combination traction slip- and brake slip-controlled brake system comprises a brake pressure generator (1) with an auxiliary energy supply system (2) and a pressure compensating reservoir (3) and electromagnetically actuatable valves (4-11) in the pressure fluid supply conduit to the wheel brakes (34-37) and in the return conduit (28, 28', 28") to the pressure compensating reservoir (3). In addition, a valve arrangement (13, 29, 30, 31) is provided and through which pressure from the auxiliary energy supply system (2) can be introduced the pressure fluid return conduit (28, 28', 28") and by way of outlet valves (8, 9) into the wheel brakes (34-37) of the driven vehicle wheels, with the purpose of controlling the traction slip.

Abstract: A slip-controlled brake system for automotive vehicles comprising two static brake circuits (17, 18) into which a pressure medium is introduceable from a dynamic pressure medium circuit (21, 23) during the control operation, and one dynamic brake circuit (14). Directional control valves (7, 8, 9) are interposed in the brake circuits (14, 17, 18). The directional control valves permit a reduction of the pressure in the wheel brakes and a return flow of the pressure medium to the storage reservoir (3). In addition, two pressure-controlled three-way/two-position valves (40, 40') are interposed in the rear wheel brake circuit (14) between the rear axle regulating valves (6, 9) and the wheel cylinders of the rear wheel brakes (HL, HR). The valves are actuated by the pressure in the front wheel brake circuits (17, 18).

Abstract: A booster unit for moving a vehicle on a slope and having a booster and a master cylinder coupled to the booster, comprising a brake fluid pressure holding valve having an actuator and provided at a brake fluid pressure piping system for either maintaining or releasing the brake fluid pressure in accordance with the conditions of the vehicle on a slope, a plurality of sensors for detecting the vehicle conditions and a control unit including a microprocessor having a CPU, a RAM, and a ROM so as to receive detected signals from the sensors and to calculate and produce control signals to the actuator of the brake fluid pressure holding valve in accordance with the conditions of the vehicle on a slope, and a method of controlling the booster unit. With this construction, a smooth moving of the vehicle can be realized on a slope.

Abstract: A hydraulic pressure control device in a vehicle anti-skid braking system includes a brake master cylinder, a wheel brake actuating cylinder for braking a wheel in response to a fluid pressure from the brake master cylinder, and a directional control valve actuatable in response to a control signal from a control unit which detects a wheel condition such as wheel skidding, for returning a braking fluid from the wheel brake actuating cylinder via a return passage to a fluid pressure supply passage connected to the master cylinder. The return passage has an accumulator for storing part of the fluid from the wheel brake actuating cylinder in an anti-skid control mode. A fluid overflow from the accumulator is delivered via a restriction in the supply passage to the master cylinder to act on the brake pedal as a pedal reaction.

Abstract: An auxiliary manual and physically controlled fluid pressure handling apparatus for vehicular pneumatic systems induced into the braking system to become a tool to aid the operator in providing rapid OFF-and-ON impulse or conventional braking, the selection of which is dependent upon the amount of force applied by the operator against the brake pedal, which also controls the frequency of intermittent application of the brakes by the apparatus.

Abstract: In an anti-lock system for a vehicle having a first valve arranged in a brake fluid pressure transmission line from a master cylinder to each brake device to operate under an anti-lock control signal, a second valve arranged to open for reducing the brake fluid pressure, a pressure fluid return device arranged to bring a brake pressure fluid into an accumulator for returning the pressure fluid to the upstream side of the first valve and a gate valve arranged in between the first valve and the master cylinder, the gate valve is provided with a balance piston which is arranged to receive at one end thereof the pressure fluid brought into the accumulator and to receive the pressure fluid of the brake device at the other end; and a shut-off valve device arranged at an axially intermediate part of the balance piston to close a passage between the master cylinder and the first valve according to the balance piston.

Abstract: In a body (3) enclosing at least one brake-pressure control device actuated manually (1, 1') there is mounted an isolating and pressure-reducing solenoid valve mechanism (18, 24) which selectively establishes communication between a brake circuit (22) and, on the one hand, the fluid outlet (8) of the device (1) and, on the other hand, a reservoir (10), the solenoid valve mechanism comprising a discharge end (30) emerging in an extension (33) of the reservoir (10).

Abstract: A hydraulic brake system with slip control for automotive vehicles comprising a master cylinder (2) pressurizable by a hydraulic power booster (1), in which system valve(s) (31,27,32,28,33,23) are inserted between the master cylinder (2) and the wheel brakes (29,30,24,25) connected to the master cylinder (2) which allow pressure fluid removal from the wheel brakes (29,30,24,25) that can be replenished out of the pressure chamber (19) of the hydraulic power booster (1) by way of a change-over valve (36). A stroke limitation of the brake pedal (8) is effected during slip control. The end surface of the master cylinder piston (5) close to the working chamber (16) being larger than the is effective surface of the booster piston (4), and wherein a stepped piston is employed as master cylinder piston (5) with an annular surface (18) thereof being adapted to be acted upon in the actuating direction by the pressure prevailing in the working chamber (16).

Abstract: The present invention concerns a control valve for use in a vehicle anit-lock braking systm adapted to control the application of pressurized brake fluid to at least one selected vehicle brake. The valve includes an outer housing having an inlet coupled to receive pressurized brake fluid from the vehicle master cylinder and an outlet coupled to supply pressurized brake fluid to the selected vehicle brakes. A passageway is formed in the housing for connecting the inlet to the outlet. A normally open isolation valve is located in the passageway and is utilized to control the flow of fluid through the passageway between the inlet and the outlet. When an incipient wheel lock condition is detected, the isolation valve can be closed to prevent a further increase in pressure to the controlled brakes and to hold the pressure supplied to the controlled brakes at a relatively constant level.

Abstract: A parking brake control device has a differential area shuttle valve which has an outlet connected to a brake actuator and a larger area of a poppet directed to an inlet connected to a control valve for applying a parking brake pressure and a smaller area of the poppet facing a second inlet connected to a service brake pressure such that in the event of simultaneous application of parking brake and service brake pressures the shuttle valve will be moved to close off the inlet to the service brake pressure while introducing park brake pressure to the brake cylinder.

Abstract: A wheel cylinder is formed in the brake caliper for each wheel of a vehicle and brake fluid is supplied from a master cylinder to this wheel cylinder by way of a fluid passage. A brake piston is provided inside the wheel cylinder and includes a piezoelectric piston device inside. By the application of voltage, this piezoelectric piston device expands and contracts the brake piston. A control valve is provided in the fluid passage to open and close it to selectively partition off the master cylinder. When the control valve has closed the passage, a voltage is applied to the piezoelectric piston device to expand it and control the pressure acting on the brake piston in the wheel cylinder to vary the braking force.

Abstract: The invention is directed to a fail-safe brake arrangement for hydraulically powered road rollers. The operating means of the brake system are completely separate from the normal road brake of the roller thereby enabling the fail-safe brake to be manually operated by the driver in an emergency situation. The brake also operates automatically as soon as the hydraulic system of the roller ceases to function. The fail-safe brake according to the invention utilizes the oil pressure to compress one or more springs in a spring brake chamber. As soon as the oil pressure falls to zero or below a certain value, the energy stored in the springs is utilized to apply the brake and bring the vehicle to a halt.

Abstract: An auxiliary air brake system is provided for a mobile vehicle which has a drive selector having reverse and other positions and which has a main air brake system which includes a plurality of compressed air tanks, main conduit including a foot brake line and a hand brake line for connecting at least one of the tanks to wheel brake chambers, and air control valves in the main conduit for controlling air pressure at the wheel brake chambers.

Abstract: A brake control system for a railway vehicle having separately operated independent and automatic brake controls for controlling brake pressure via a double check valve and a multi-piston relay valve, wherein an adjustable regulating valve is set to exhaust the independent brake control pressure acting on one piston of the multi-piston relay valve when the relay valve delivery pressure (brake cylinder pressure) exceeds a predetermined value, to thereby limit the maximum brake cylinder pressure attainable from the combined independent and automatic brake controls unless the automatic brake pressure exceeds that predetermined value.

Abstract: A load compensating valve for a compressed air brake system for railroad vehicles having air spring devices. The load compensation valve includes a supply chamber and an output chamber which are interconnected by a supply valve and an exhaust valve. A balance piston responsive to air spring pressure for controlling the pressure in the output chamber. A check valve disposed in parallel with the supply valve to allow the output chamber to discharge when the supply chamber is exhausted.

Abstract: A load responsive valve for the braking of vehicles having load supporting air springs. The air spring pressure is employed to regulate the brake pressure through conventional proportioning-type valving. A pilot valve senses the application and release of the vehicle brakes in order to nullify operation of the air spring operated control piston so long as the brake is released, in order to reduce component wear and air consumption due to valve oscillation resulting from air spring pressure variation as the car jounces in service. This is accomplished by pilot pressure supplied via the pilot valve to counteract the air spring pressure acting on the control piston. During a brake application, the pilot valve exhausts this pilot pressure to permit the air spring pressure to operate the control valve in a normal manner.

Abstract: A brake control system in which the master cylinder has two pressurizing chambers for each brake circuit. Three brake circuits are disclosed in detail. One piston of each set of pressurizing chambers is directly applied by brake pedal force. The other piston of each set receives brake pedal force through resilient means, with additional force supplied by suitable servomotors. The servomotors are individually controlled to provide power-assist when appropriate, or to decrease the forces supplied by them to control wheel slip or wheel spin.

Abstract: Control system for electro-pneumatic compressed air brakes for rail vehicles with a servo valve (1) for control of a pilot pressure and for actuation of electrical contacts (40, 41) operable over a coupling (4) such that, at the beginning of an adjustment of the servo valve in the braking direction, at least one contact (40) is always closed while, at the beginning of an adjustment in the releasing direction, a different contact (41) is closed. The two contacts control the excitation of a brake and release contactor (50, 51) monitoring a brake and release circuit (56, 62) which, when switching, interrupts the circuits monitored by the contacts (40, 41) of the servo valve (1) by opening the coupling (4). Holding circuits for the brake and the release contactor (50, 51) are monitored by contacts of a second switching system (34); a piston (25) actuated by the pilot pressure against the main air line pressure serves to control the latter contacts.

Abstract: A pneumatic controller for actuating a retarder of the motion of a vehicle. Inlet and exhaust valves are actuated by a pair of diaphragms responsive to the pressure of the air applied to the brakes of a vehicle and the pressure of the air actuating the retarder. The valves are preferably on a common stem and operatively associated with the diaphragms by an actuator rod responsive to the resultant of forces produced by both of the diaphragms.

Abstract: This invention relates to a railway braking system in which a drop in brake pipe pressure calling for brake application initiates a pilot pressure and this pilot pressure is used to operate other valves pneumatically to effect braking. In this system, during the initial part of a brake application, air flows to atmosphere through a pilot exhaust choke. To avoid problems during release of the braking, it is proposed to isolate or restrict this pilot exhaust choke during at least the initial part of the brake application stage. To achieve this, an interlock valve is introduced into a passage between a release ball valve and a pilot exhaust choke. The interlock valve is operated by a diaphragm biassed by a spring and separating two chambers. Brake pipe pressure is applied to the first chamber and auxiliary reservoir pressure to the second chamber. A very small drop in brake pipe pressure closes the valve and cuts off connection between the release ball valve and the pilot exhaust choke.

Abstract: A brake fluid pressure control apparatus in a skid control system includes electromagnetic valves arranged between a master cylinder and a wheel cylinder, receiving control signals of a control unit measuring the skid condition of the wheel to control a brake fluid pressure to the wheel cylinder; a hydraulic reservoir reserving the brake fluid discharged through the electromagnetic valves from the wheel cylinder; a pressure fluid supply conduit connecting the master cylinder with the electromagnetic valves and containing a first check valve which allows the flow of fluid in the direction of the electromagnetic valves; a fluid pump for returning brake fluid from the hydraulic reservoir into a portion of the fluid pressure supply conduit between the first check valve and the electromagnetic valves; a pressure fluid return conduit connecting the master cylinder with the wheel cylinder and containing a second check valve which allows the flow of fluid in the direction of the master cylinder; and a controllable ch

Abstract: A vehicle brake actuator has a piston (23) within a cylinder (22) for urging friction pad assemblies (19, 20) into braking engagement with a brake disc (21). The actuator incorporates a pressure accumulator (3) and an electrical valve (9) operable to supply pressure from the accumulator to the cylinder in response to the action of a brake pedal or other control device. The actuator may also incorporate a pump (1) for charging the accumulator, together with other equipment such as skid control device. A braking system incorporates one or more of the actuators and device for producing an electrical output in response to displacement of the brake control device for supply to the valve.

Abstract: An air brake system augments the braking force available while parking without interfering with the operation of the parking brakes. The brake system includes a service brake, a pilot check valve and, typically, a quick release valve. The quick release valve and pilot check valve are interconnected in two alternative ways among the service and spring brake lines and the service brake cylinder. When the spring brake line is pressurized the system acts normally. However, when the pressure on the spring brake line is eliminated the pilot check and quick release valves trap the pressurized air within the service brake. This keeps the service brake for each individual wheel actuated. Pressurizing the service brake line pressurizes the service brake regardless of the condition of the spring brake line. Safety valves can be incorporated in the brake systems to insure that the pressure within the service brake chamber does not exceed a predetermined value.

Abstract: In an anti-skid braking system a supply of operating fluid from a master cylinder to a vehicle brake is modulated in accordance with skid signals from a skid sensing mechanism. The system incorporates an hydraulic pump of the double-acting type having a plunger working in a bore and a working chamber which is in communication with a modulator assembly adapted to control brake application following skid correction.

Abstract: A hydraulic braking system including hydraulically operated brakes and a hydraulic master cylinder for controlling the operation of the brakes. A conversion assembly is used for providing power-assisted braking in the system. The conversion assembly is capable of operating in a manual mode to couple master cylinder pressure to the hydraulic brakes or in a power-assisted mode to supply an amplified hydraulic braking pressure to the hydraulic brakes in response to the master cylinder pressure. The conversion assembly is also operable to provide deceleration control during braking to prevent skidding of the wheels being braked.

Abstract: An accelerator device for a three-pressure control valve of an air brake system on a railway vehicle has a control piston one side of which is subjected to air line pressure and the other side to pressure in a control chamber such that when the pressure in the control chamber predominates the control piston opens an accelerator valve between the air line pressure and a valve chamber. A monitor valve is between the valve chamber and a transfer chamber which continuously communicates to the atmosphere through a throttle orifice. A first piston operates the monitor valve and is subjected in the closing direction of the monitor valve to the action of braking pressure against the effect of a spring force.

Abstract: A hydraulic braking system including hydraulically operated brakes and a hydraulic master cylinder for controlling the operation of the brakes. A conversion assembly is used for providing power-assisted braking in the system. The conversion assembly is capable of operating in a manual mode to couple master cylinder pressure to the hydraulic brakes or in a power-assisted mode to supply an amplified hydraulic braking pressure to the hydraulic brakes in response to the master cylinder pressure. The conversion assembly is also operable to provide deceleration control during braking to prevent skidding of the wheels being braked.

Abstract: Anti-skid type vehicle brake system which comprises a master cylinder, one or more wheel brake actuators, a brake pressure supply line extending between master cylinder and brake pressure supply line, a fluid return line between master cylinder and brake pressure supply line, a skid control valve for connecting brake actuator to the return line when wheel lock or similar condition is detected, fluid pressure actuated regulating valve for introducing a restriction to the brake pressure supply line when actuated by fluid pressure produced in the return line.

Abstract: An anti-skid brake control system comprises a cylinder casing having a first chamber connected with a master cylinder and a second chamber in communication with wheel brake cylinders, a cut-off valve disposed within the first chamber for selectively interrupting fluid communication between the first and second chambers, and a hydraulic capacity controller including a plunger axially reciprocable within the first chamber and operatively engaged at its both ends with the cut-off valve and a piston reciprocable within a vacuum servo-motor, the plunger being retracted by the piston to activate the cut-off valve and thereafter to increase the capacity of the second chamber to decrease the braking pressure applied to the wheel brake cylinders.

Abstract: A force limiting device for a parking brake actuator is arranged in series with a service brake actuator to limit the maximum force of the two actuators to the maximum force from one of them. One actuator works from hydraulic pressure and the other from air pressure. Thus, an overflow valve controls the hydraulic pressure and is forced closed by an adjustable spring and open by either hydraulic pressure in a valve chamber or by air pressure exerted on a valve plunger. Both sides of the valve are maintained at the hydraulic pressure while the valve outlet is both closed or open.

Abstract: An improvement in pneumatic anti-skid braking systems for at least one wheel of a vehicle, of the type having a first valve system for causing a controlled reduction in braking pressure in a brake actuator upon reception of a control signal from an anti-skid control device sensitive to the dynamic state of at least one wheel of the vehicle, and a second valve system for causing a subsequent controlled rise in pressure after the signal from the anti-skid control device has been removed, the improvement being the provision of an accumulator in parallel with the first valve system and having two unidirectional valves, one at each side, which permit the accumulator to charge up to the braking pressure during normal braking, store this pressure upon anti-skid release of the braking pressure, and then deliver its charge to the circuit, causing a rapid increase of braking pressure after the anti-skid control signal is removed from the first valve system.

Abstract: A brake pressure modulating control valve for a hydraulically operated brake system. The control valve includes a spool associated with an air spring chamber. The system includes equipment for modulating the air pressure in the air chamber for constantly and concurrently modulating the pressure of the hydraulic fluid in the brake system.

Abstract: A booster operated master cylinder piston for use in an anti-skid braking system includes a modulator piston located between the master cylinder piston and the booster valve assembly. In the event of a skid the pressure of booster fluid acting on the modulator piston is relieved.

Abstract: A valve unit for controlling air flow and braking pressure in the brake cylinder of a pneumatic braking system. The valve unit has an inlet and an outlet valve assembly each of which are controlled by a solenoid valve, which is in turn controlled by an electronic braking control system. In the inlet valve assembly there is a valve diaphragm which on one side is biased by one pressure to close the valve unit, and which on the opposite side is biased by two pressures to open the valve unit. The ratio between the areas affected by the respective pressures is selected in such a way that the brake cylinder pressure is raised in essentially constant steps.