Abstract: The control valve includes a pressure sensing piston disposed in a housing bore having a first active surface exposed to pressure of the front wheel brake circuit and a second active surface exposed to pressure of the rear wheel brake circuit, the second active surface being smaller than the first active surface. A stepped piston having an axial bore therein communicating with the rear wheel brake circuit is also disposed in the housing bore with the smaller diameter portion thereof being axially guided in a bore of the sensing piston. The end of the axial bore of the stepped piston in the bore of the sensing piston provide a valve seat and the sensing piston causes a valve closing member to effect a reduction of pressure in the rear wheel brake circuit when a given brake pressure is achieved.

Abstract: A hydraulic braking system for a vehicle having independent dual braking circuits delivers the hydraulic pressure produced in a master cylinder to each wheel cylinder mounted on the front and rear wheels. A pressure control valve is provided with a portion similarly constructed to the ordinary proportioning valve. A first piston disposed in this portion for the hydraulic pressure control operation confronts a second piston, which is with a spring constantly biased theretoward and provided with a small-diametered portion and a large-diametered portion. The second piston is placed such that the small-diametered portion thereof confronts the first piston in one air chamber and the large-diametered portion thereof is extended into another air chamber, an end surface of which large-diametered portion on the side of the small-diametered portion being affected by the hydraulic pressure from the other or opposite circuit from one circuit wherein the pressure control valve controls the hydraulic pressure.

Abstract: A wheel cylinder includes a housing defining a bore. A piston is reciprocably received in the bore and cooperates with the housing to define a pressure chamber. The wheel cylinder comprises a passage for supplying pressurized fluid to the pressure chamber from a fluid pressure source. The supply passage includes a first portion defined by an annular groove on the piston and a blind axial bore in the piston which communicates with both the annular groove and with the pressure chamber. A valve apparatus is received in the blind bore and modulates the fluid pressure supplied to the pressure chamber as a function of the fluid pressure provided by the pressure source.

Abstract: A brake pressure control valve controls the hydraulic pressure supplied to rear wheel brakes in two independent circuits of a dual hydraulic braking system of a vehicle. The valve includes two valve bodies slidably received in a bore of a housing and movable toward one another upon receiving hydraulic pressure, valve seats formed respectively in the valve bodies, a free piston assembly the opposite ends of which are mounted slidably and sealingly on the valve bodies, and valve members mounted on opposite ends of the free piston assembly and defining valve heads cooperating with the valve seats in the valve bodies.

Abstract: A back-to-back proportioning valve assembly for a cross-split braking system is disclosed. The proportioning valve assembly comprises an assembly housing defining a substantially cylindrical bore extending therethrough. The bore defines first and second rear brake outlet openings. In the assembly housing are disposed a pair of inlet passages extending within the cylindrical bore connected with respective first and second master cylinder chambers. A pair of front brake outlet openings are also disposed in the assembly housing. First and second proportioning valves are positioned in back-to-back relationship within the cylindrical bore adjacent respective first and second rear brake outlet openings for proportioning the inlet pressure to the rear brake outlets. A pair of bypass channels, for bypassing each of the proportioning valves, are provided to be opened upon failure of one of the braking systems.

Abstract: In a known tandem master cylinder with a regulator, machining and assembly of the parts is complicated which renders the master cylinder costly. Moreover, such an arrangement is only realizable with master cylinders having a large diameter. There are also functional disadvantages, particularly in the event of failure of one brake circuit, the brake fluid volume consumption of the other brake circuit is materially increased which results in an additional increase of the pedal travel. To avoid these shortcomings, the present invention provides a tandem master cylinder with a regulator including an arrangement, which in the event of failure of the front-axle brake circuit, mechanically actuates the regulator valve coupled to the rear-axle brake circuit by a pressure piston to keep the regulator valve in the open position to enable unreduced braking pressure to be coupled to the rear-axle brake circuit.

Abstract: Brake power control units for two-circuit brake systems are known in which a control piston and a locking piston are provided. The control piston reduces the brake pressure of the rear axle brake circuit in relation to the brake pressure of the front axle brake circuit and the locking piston acts on the control valve in the case of failure of the front axle brake circuit in such a way that the reducing effect for the rear axle brake pressure is neutralized. The two pistons of this known unit are arranged one behind the other which requires a great overall length for the control unit. According to the present invention, the overall length of the control unit is reduced by disposing the two pistons coaxial with respect to each other with the control piston enclosing the locking piston.

Abstract: A buffer or insulation member is interposed between the housing and the movable spring seat of a pressure control valve assembly and constructed to come into contact with the spring seat slightly before the piston abuttingly engages with the wall section, whereby the piston strikes against the wall section at a speed sufficiently reduced to prevent the production of an unpleasant striking sound.

Abstract: A pressure control valve assembly for a fluid brake system has a piston which rapidly strikes at its one end portion against a shock absorbing abutment member in a concavity of a housing wall section when a fluid under pressure is rapidly released from the valve assembly, thereby preventing the production of an unpleasant sound at such times.

Abstract: A control valve assembly for a dual circuit braking system has two valves controlling the pressure in the respective circuits. In order to ensure substantially equal braking pressures in the circuits, a pressure equalizing piston is provided which is free floating in a bore interconnecting outlets of the valve assembly. The braking pressure can thus be equalized even after closure of the valves. One valve is preferably inertia-responsive.

Abstract: A wheel cylinder in a brake assembly includes a housing for movably carrying a pair of pistons. An intermediate wall of the housing separates the pair of pistons from each other and cooperates with each piston to substantially form a first chamber facing one of the pistons and a second chamber facing the other piston. An inlet communicates fluid pressure to the chambers via a first path and a second path within the housing. A pressure responsive member is disposed within one of the paths and is biased to a position opening communication through the one path. When the fluid pressure within one of the chambers reaches a predetermined value, the pressure responsive member is movable to restrict fluid communication to the one chamber while the fluid pressure within the other chamber is free to increase in value during actuation of the wheel cylinder.

Abstract: In order to prevent an excessive braking of the rear wheels of the vehicle, brake pressure regulators are incorporated in the rear wheel brake circuit generally including a control piston and a control valve. To prevent the regulator from becoming effective upon failure of the front wheel brake circuit, a by-pass is provided which is opened by failure of the front wheel brake circuit. The known regulators of this type are expensive to manufacture and necessitate much space. The brake pressure regulator with by-pass of the present invention has the by-pass between the inlet chamber and the outlet chamber disposed in the control piston of the regulator. The by-pass terminates at one end of the control piston close to a closure piston subject to pressure from the front wheel brake circuit to maintain the by-pass closed as long as the front wheel brake circuit is intact.

Abstract: A fluid pressure control device for incorporation in a vehicle braking system between a master cylinder and a wheel brake cylinder which includes a housing provided with an inlet port for connection to the master cylinder, an outlet port for connection to the wheel brake cylinder, and a valve chamber communicating at one end thereof with the inlet port and at the other end thereof with the outlet port, an inertia-controlled valve including a valve seat provided in the valve chamber to permit the flow of fluid between the inlet and outlet ports therethrough, and an inertia-controlled valve element housed within the valve chamber to cooperate with the valve seat to cut off the flow of fluid from the inlet port to the outlet port when the valve element is subjected to a deceleration in excess of a predetermined value, a bypass passage for permitting direct fluid flow from the valve chamber into the outlet port, a check valve including a valve seat provided within the bypass passage and a valve member cooperating

Abstract: A pressure control valve for use in vehicle hydraulic diagonal split brake systems. The valve includes two valve pistons which operate to limit the fluid pressure delivered to the rear wheel brakes relative to that delivered to the front wheel brakes. The valve also includes a failure warning mechanism having a switch actuating piston. In the event of a failure in one branch of the diagonal split brake system, the switch actuating piston operates to simultaneously preclude the two valve pistons from limiting the rear wheel brake pressure so that the rear wheel brake in the unfailed branch of the brake system can develop the maximum braking effort for vehicle emergency braking.

Abstract: A device for controlling the hydraulic pressure in the hydraulic braking system of a vehicle, in such a manner that the hydraulic pressure in the rear wheel cylinder is increased at a rate smaller than that in the front wheel cylinder, after a predetermined level of deceleration of the vehicle is reached. The device has a valve chamber in which a ball valve is disposed movably. A differential piston has two opposing pressure receiving surfaces of different areas exposed in the inlet and outlet chambers. The arrangement is such that, when the predetermined level of deceleration is reached, the ball valve is moved due to its inertia to a position for interrupting the communication between the inlet and the outlet chambers. Once the communication between two chambers is interrupted, the pressure in the master cylinder is transmitted across the differential piston. The transmitted pressure is lowered at a rate corresponding to the ratio of the areas of pressure receiving surfaces of the differential piston.

Abstract: A fluid brake pressure control system having a hydraulic pressure control valve device controlling the wheel cylinder hydraulic pressure by the inertia in response to the vehicle deceleration with such device being located in a circuit between a master cylinder and wheel cylinders.

Abstract: A braking hydraulic pressure control unit for a motor vehicle including a differential-acting piston having a plurality of pressure bearing portions facing an inlet compartment and an outlet compartment communicating with a master cylinder and rear wheel cylinders, respectively, of a vehicle braking system. The differential-acting piston is formed with shoe clearance compensating piston segments operative to reduce an inflow of a braking fluid into a spherical valve chamber at initial stages of brake application whereby unfavorable influences which would otherwise be exerted by the size of shoe clearances on a spherical valve at initial stages of brake application can be prevented.

Abstract: In a known motorcycle brake system with a brake force regulator, the pedal master cylinder acts on the front-wheel brake and on the rear-wheel brake, and the hand master cylinder acts only on the front-wheel brake. The brake force regulator's control behavior is influenced by the hand master cylinder. This known system has functional disadvantages because the rear-wheel brake becomes evacuated if only the hand master cylinder is actuated. The motorcycle brake system with brake force of the present invention eliminates this disadvantage by arranging for a brake caliper of the front-wheel brake to be actuated by the regulated pressure of the pedal master cylinder and the rear-wheel brake to be actuated by the non-regulated pressure of the pedal master cylinder.

Abstract: A brake-force regulator for dual-circuit brake systems including first and second stepped pistons disposed in a multiple-step housing bore such that the end of the smaller diameter portion of both the first and second piston abut one another. An inlet chamber coupled to the master cylinder is provided adjacent the annular surface between the larger diameter portion and the smaller diameter portion of each of the first and second pistons. A first output chamber coupled to one of the brake circuits is provided adjacent the end of the larger diameter portion of the first piston and a second output chamber coupled to the other brake circuit is provided adjacent the end of the larger diameter portion of the second piston. A first valve is associated with the first piston to couple the associated one of the inlet chambers to the first outlet chamber and a second valve is associated with the second piston to couple the associated one of the inlet chambers to the second outlet chamber.

Abstract: A hydraulic pressure control system for a split brake system which includes a tandem master cylinder having first and second hydraulic pressure sources, at least first and second wheel cylinders, a first brake pressure supply line communicating the first source with the first wheel cylinder, a second brake pressure supply line communicating the second source with the second wheel cylinder, a first hydraulic pressure control device positioned within the first supply line for controlling output hydraulic pressure transmitted therefrom with respect to hydraulic pressure transmitted from the first source, and a second hydraulic pressure control device positioned within the second supply line for controlling output hydraulic pressure transmitted therefrom with respect to input hydraulic pressure transmitted from the second source in response to the output hydraulic pressure transmitted from the first control device such that the output pressures of the first and second control device are proportionally controlled.

Abstract: A pressure control valve assembly in a split brake system having two separate pressure lines comprises two valve pistons subjected to pressure from separate pressure sources so as to control the outlet pressure admitted to the respective rear wheel brakes. The valve assembly further comprises two movable members each in alignment with each of two valve pistons and subjected to the pressure of two pressure lines at each end thereof and two springs each interposed between a respective piston and movable member for normally urging the piston in the valve closing direction. The hydraulic failure of one of two pressure lines causes the movable member to move in the direction wherein no biasing force of the spring may be imparted to the valve piston.

Abstract: A controlling device used in a dual hydraulic braking system of a vehicle including a master cylinder which produces hydraulic braking pressure in response to the pedal depression, wheel cylinders disposed on each wheel, two mutually independent circuits for delivering the braking pressure from the master cylinder to each wheel cylinder, and a regulating valve disposed at least in one circuit of the two for controlling the hydraulic braking pressure delivered to the wheel cylinder.

Abstract: A brake pressure control apparatus for a split braking system includes a pair of brake pressure proportioning control valve assemblies between separate fluid pressure sources and wheel cylinders for each of braking fluid lines. When one of separate sources relating to one of the proportioning control valve assemblies fails to operate, the other of the proportioning control valve assemblies is forced into its non-operating position so that the braking pressure is directly transmitted from the other fluid pressure source to the other of wheel cylinders.

Abstract: A dual master cylinder has modular proportioners attached to an outlet from each pressurizing chamber. The master cylinder is shown installed in an X-split vehicle brake system. The master cylinder assembly includes a pressure failure warning device. The arrangement provides a minimum number of leak points, permits the master cylinder and the modular proportioners to be built and tested separately, and enhances serviceability since the modular proportioners can be separately replaced without removing the master cylinder. It also permits the master cylinder to be of a universal type with modular proportioners of various proportioning characteristics used in accordance with the particular vehicle application.

Abstract: A proportioning valve in a master cylinder is pressure responsive to control the flow of fluid to a wheel cylinder. An inertia sensing member is responsive to the deceleration of a vehicle and is operatively connected to the proportioning valve to control the operation thereof. The inertia sensing member defines a neutral position relative to a housing supporting the proportioning valve. During braking the inertia sensing member generates a force biasing the inertia sensing member toward the proportioning valve, but remains in the neutral position to oppose actuation of the proportioning valve. The proportioning valve includes a sleeve and a pilot which extends through the sleeve to engage the inertia sensing member.

Abstract: A tandem master cylinder for a vehicle split hydraulic braking system which has disc brakes in one part of the system and drum brakes in the other half. One of the pistons in the master cylinder is prevented from developing a substantial pressure until a predetermined pressure is developed by the other piston by virtue of a control piston working in a blind bore in one of the pistons. Hydraulic fluid is trapped in a control chamber formed by the blind bore and the control piston by a first valve means and released by a second valve means at the predetermined pressure. The arrangement allows pressure to the disc brakes to be delayed while pressure to the drum brakes is overcoming the effects of the usual pull-off springs.

Abstract: A control valve for use in an automotive brake system for controlling the brake fluid pressure in rear-wheel cylinders of the type include an inlet chamber communicated with a master cylinder, an outlet chamber in communication with the rear-wheel cylinders, a valve chamber in hydraulic communication with both of the inlet and outlet chambers, the latter being communicated through a valve port, a ball valve floatingly disposed within the valve chamber and actuable to close the valve port when the deceleration of an automotive vehicle reaches a predetermined level, and a differential piston with its free ends disposed in the inlet and outlet chambers, respectively, to be exerted with the brake fluid pressure therein.

Abstract: A hydraulic brake control assembly is provided in which a proportioning valve is actuated to reduce fluid pressure to be supplied to rear cylinders from a master cylinder in accordance with the vehicle deceleration. An inertia ball is adapted to control the movement of the proportioning valve via a flexible disc valve to increase or reduce the fluid pressure supply to the rear cylinders. The disc valve is deformable to open the proportioning valve if the pressure of the master cylinder exceeds a predetermined level.

Abstract: A control valve having relay and proportioning pistons has an intermediate piston which controls air pressure access to a blind flow chamber. At a relatively low value of control air pressure, the intermediate piston is shuttled into a position which closes and traps the existing value of control air pressure in the blind flow chamber. The trapped constant value of air pressure in the blind flow chamber operates on a larger area piston whose force is added to the forces derived from further increases in control air pressure to provide a first region of output air pressure having incremental increases smaller than the input. When the input air pressure reaches a certain value, a second region of output air pressure is reached where further increases in input air pressure cause metered addition to the air pressure in the blind flow chamber and thus produces incremental output increases greater than incremental input increases.

Abstract: A pressure reducing valve for a vehicle braking system, comprises an inlet and an outlet communicating with each other through a radial port, and an elastomeric seal movable relative to the port between a closed position in which the seal covers the port and an open position. The seal is arranged to cover the port on the outlet side thereof so that the interface between the seal and the port is subjected to inlet pressure.

Abstract: A load-responsive pressure reducing valve assembly for hydraulic brake systems to be interposed between a brake master cylinder and the rear wheel brake cylinders of a wheeled vehicle. The valve assembly includes a fluid pressure proportioning valve which restricts the flow of fluid from the master cylinder to the brake slave cylinders during a predetermined range of increasing fluid pressure supplied therefrom to the brake slave cylinders. The valve assembly also includes a deceleration sensing valve having a spherical inertia-responsive member that is responsive to a predetermined rate of vehicle deceleration to travel a predetermined distance up an incline to close off the supply of hydraulic fluid to a control chamber wherein the fluid pressure acts on a portion of the aforesaid proportioning valve, thus setting the reduction starting pressure of the fluid pressure proportioning valve.

Abstract: A brake actuating pressure proportioning valve is positioned in a vehicle rear brake circuit. The valve is sensitive to vehicle load to change the rear brake pressure point at which proportioning begins. The valve is also sensitive to front brake circuit pressure. If a significant decrease of front brake circuit pressure occurs, a delay piston is moved to follow the proportioner piston to a predetermined extent. In this condition the delay piston keeps the proportioner from operating in a proportioning mode, permitting full rear brake circuit pressure to be delivered without proportioning action. The delay piston is spring loaded to permit a significant pressure delay in proportioning action before it is moved toward its original position with increasing rear brake circuit pressure.

Abstract: There is provided a brake-force distributor, wherein the normally controlled rear-axle brake circuit is no longer influenced by the distributor if the front-axle brake circuit has failed. This is achieved by arranging the valve seat at a sleeve held in the operating position by the front-axle brake pressure. In the event of failure of the front-axle brake circuit, the rear-axle braking pressure will displace the sleeve into a position in which the distributor is not allowed to close.

Abstract: A two-circuit brake system for motor vehicles with a shiftable master brake cylinder which includes two pressure spaces for the two brake circuits, of which the pressure space for the front axle brake circuit has a larger cross section than the pressure space for the rear axle brake circuit and which are connected with each other by a line extending externally of the master brake cylinder, whereby a shifting valve operating in dependence on the vehicle load is arranged in this line which is able to establish and interrupt the connection between the two pressure spaces; an intermediate piston is arranged between the two pressure spaces in the master brake cylinder coaxial to the two pressure pistons, which is freely movable within a guide sleeve of smaller diameter and is provided with central extensions on both sides thereof for the mechanical cooperation with the two pressure pistons; the shifting valve is thereby adapted to be shifted as a function of the load, of the pressure prevailing in the brake cylind

Abstract: A control valve assembly for a vehicle braking system comprises a control valve having a control valve operating member operable to control communication between an inlet and an outlet, a pivoted lever arrangement subjected to an input force applied by a spring and applying an output force to the valve operating member, and a device for varying the lever ratio of lever arrangement in dependence upon vehicle loading. The input force applied to the lever arrangement by the spring is substantially constant and independent of vehicle loading, variations in the lever ratio varying the load transmitted to the valve operating member.

Abstract: A vehicular hydraulic brake apparatus comprises a tandem master cylinder having front and rear sections respectively connected by independent front and rear wheel braking hydraulic circuits to front and rear wheel brake cylinders. The rear wheel braking hydraulic circuit is provided therein with a deceleration-responsive braking pressure control device having pressure inlet and outlet normally communicated with each other. The pressure control device has an inertia valve comprising a ball and a valve seat and a first differential piston both disposed between the pressure inlet and outlet. When the deceleration of an associated vehicle reaches a predetermined value, the ball is moved to close the valve for thereby interrupting the communication between the pressure inlet and outlet. In normal operative condition of the apparatus, the differential piston is operative to modulate the inlet pressure after the valve closure and transmit the modulated pressure to the rear wheel brake cylinders.

Abstract: A hydraulic braking system of the split type including a fluid pressure control device which is adapted to reduce or stop the rate of increase of an output fluid pressure to wheel cylinders when a certain critical level is reached by an input fluid pressure delivered from a master cylinder, wherein the rates of increase of such critical level and the output fluid pressure if higher than the critical level are lowered when one of the split hydraulic circuits of the braking system fails or, if the rate of increase of the output fluid pressure higher than the critical level, only the critical level of the pressure is lowered.

Abstract: A valve device for use in split liquid pressure vehicle braking systems to control rear brake pressure comprises a plunger assembly in a cavity in a housing, the cavity being closed at one end. The plunger assembly has a central land between two smaller end lands. The central land slides within a central portion of the cavity which is between two smaller portions of that cavity. The central portion and the closed end portion of the cavity are formed in a main valve body and the other cavity portion is formed in another body which is carried by the main valve body. The plunger assembly carries a bar which co-operates with the shoulder between the central portion and the closed end portion of the cavity and with a valve unseating pin to unseat a ball in a passage through the central land. A biasing spring urges the plunger assembly towards the closed end of the cavity against the action upon the plunger assembly of front brake pressure which acts between the plunger assembly and the closed end of the cavity.

Abstract: A dual circuit brake system has a failure warning section in which the pressures in each of the circuits are sensed by a pair of pistons having a switch actuating shuttle positioned between the pistons by a pair of springs. The ends of the shuttle are telescoped in the pistons for guidance and relative movement. The switch pistons are relatively small with little travel, minimizing displacement loss. The centering springs do not have sufficient load to force the shuttle to the off position once failure in one system has occurred and the pressure in the remaining system has been released. Repair of the failed system allows pressure actuation to move the shuttle back to the deactuated position for automatic reset.

Abstract: A dual hydraulic brake system incorporating a dual master cylinder for separately pressurizing the front and rear brakes of a vehicle. A device for varying the proportion of brake pressure applied to the front and rear brakes of a vehicle is positioned between the master cylinder and the front and rear brakes. The device includes a differential area piston for decreasing the proportion of brake pressure delivered to the rear brakes above a first preselected inlet pressure. Positioned within the differential area piston is a second valve assembly which is actuated in response to attainment of a second preselected brake pressure and which blends back the pressure in the rear brake system until it attains the pressure in the front brake system.

Abstract: A brake pressure-failure warning system for use with a split or dual type brake system having two brake lines includes a stepped piston operatively associated with an electrical warning switch and supplied with brake pressure from both of the brake lines, a proportioning valve disposed within the rear wheel brake line, and three fluid chambers, two of which are usually in fluid communication through the proportioning valve and a passage. When either one of the three fluid chambers is subjected to a hydraulic failure, the two chambers are in direct fluidic communication without fluid passing through the proportioning valve, the passage in effect being utilized as a by-pass passage under such hydraulic failure conditions.

Abstract: A brake pressure failure warning system for use with a split or dual type braking system having two brake lines, includes a stepped piston associated with an electrical warning switch and supplied with brake pressure from both of the brake lines, a proportioning valve disposed within the rear wheel brake line, and three fluid chambers each fluidically connected with the stepped piston or the proportioning valve. When either one of the three fluid chambers is subjected to a hydraulic failure, the stepped piston is axially moved so as to actuate the warning switch.

Abstract: A vehicle load sensing arrangement for use with a vehicle braking system comprises an input member operating in a first bore and being subjected to the force of a road spring, a spring, such as a robust helical coil spring, subjecting the input member to a force in opposition to the road spring force, a valve having a valve member in a second bore which has a cross-sectional area smaller than the first bore, the valve member and input member being substantially in alignment, and an elastomeric member located between the input member and the valve member. The arrangement is such that only a proportion of the road spring force applied to the input member in excess of the coil spring force is transmitted by the elastomeric member to the valve member, the remainder of that excess force being transmitted to the sprung part of the vehicle.

Abstract: A brake pressure proportioner is mounted on a sprung portion of a vehicle and is attached to an unsprung portion by means of a modifying arm. The arm has ends pivoting on the unsprung portion and on a proportioner control arm so that the arm maintains a constant length during relative movements of the vehicle sprung and unsprung portions, modifying the action of the brake proportioner in accordance with such movements. The movements are proportional to vehicle load. The arm provides for compression or extension without affecting the proportioner when unsprung movements between gross vehicle curb weight (no load) and gross vehicle full weight (full load) positions are exceeded in either direction. The movement of the unsprung portion of the vehicle below the position for curb weight is known as rebound and above the curb weight position is known as jounce. The excess jounce travel beyond the gross vehicle full weight causes the arm to compress without further modifying the proportioner.

Abstract: The piston of a brake control valve assembly is balanced, during normal front hydraulic system operations, at a predetermined position to allow pressurized brake fluid from a rear master cylinder to flow into a rear wheel cylinder from between a head flange and a seal valve with a predetermined pressure. When the braking operation is sought during trouble or failure in the front hydraulic system, the piston loses its regulated balance and moves, together with a piston sleeve and the seal valve so that the effective area for receiving brake fluid pressure from a rear master cylinder becomes greater than that of the rear wheel cylinder thereby to increase brake fluid pressure transmitted to the rear wheel cylinder. The present invention features particularly the improvement, or reversewise utilization, of the conventional proportioning valve mechanism to permit a very rational brake fluid pressure boosting operation.

Abstract: A proportioning device for controlling the distribution of fluid from separate pressurizing chambers in a master cylinder to corresponding first and second wheel brakes of a vehicle. The proportioning device is adapted to respond to changes in the pressure from the separate pressurizing chambers to assure that the fluid pressure supplied to the individual wheel brakes is substantially equal at all times.

Abstract: A braking correction device comprising two correcting valves of which the inlets are separately connectible to two independent braking pressure sources and the outlets to two independent sets of brake actuators, each valve being capable of controlling the pressures at its inlet and outlet in accordance with a predetermined relationship and comprising a piston subject to resilient return spring. The correction device comprises force distributing member situated between the resilient return spring and the pistons of the correcting valves, the distributing member comprising a block of elastomeric material enclosed in a rigid shell comprising a cylindrical cavity in whose bottom the force distributing block is fitted, the cavity comprising a cylindrical edge slidable receiving an assembly comprising two projections contacting the block and co-operating with the pistons of the valves. The braking correction device is intended for a dual vehicle hydraulic brake system.

Abstract: A pressure control assembly comprises a control valve set for controlling communication between an inlet and an outlet, a control spring acting in a sense to resist closure of the valve set and a device for varying the control force of the control spring acting on the valve set. The device for varying the control force may comprise a differential pressure responsive member which moves in response to a differential pressure to move an abutment engaging the spring between normal and actuated positions to compress or expand the spring and thus vary its force.

Abstract: In a braking pressure control valve unit incorporated between a master cylinder and rear wheel brake cylinders, a check valve is assembled to directly apply the braking fluid pressure to the rear wheel brake cylinders only when the increasing ratio of deceleration drops due to breakage of the braking fluid pressure circuit for the front wheel brake cylinders.

Abstract: A safety device for an oil hydraulic braking system of a dual-type including separate oil hydraulic systems for the front and rear wheels, the oil hydraulic system being applied with a so-called proportioning element, the safety device being adapted to detect any hydraulic failure which has occurred in any portion of the entire oil hydraulic system and warn the driver of the failure due to a displacement of a single piston member from its normal neutral operating position.