Abstract: A pressure reducer device, particularly for hydraulic brake systems in motor vehicles comprises a housing having a chamber, a differential area piston movable within the chamber having a passage through which pressure is transmitted from a high pressure chamber to a low pressure chamber, and a sleeve fixed to the housing and disposed in the high pressure chamber. The differential area piston is movable in the sleeve to open and close the passage to perform a pressure modulating operation on the fluid transmitted from the high pressure chamber to the low pressure chamber.

Abstract: A valve assembly for use in a vehicle braking system comprises two valves having respective inlets for connection to separate wheel brakes. Each valve has a plunger carrying one part of a valve set which co-operates with a stationary part of the valve set to control communication between the inlet and outlet, and a spring urging the plunger in a direction to maintain the valve set open. Each plunger has opposed piston portions of different dimensions subjected to the pressure at the inlet of the associated valve to produce a net force tending to close the valve, and a further portion subjected to the inlet pressure of the other valve to produce an additional force which is removed upon failure of that inlet pressure of the other valve.

Abstract: A brake control apparatus actuated by sensing the deceleration of a vehicle includes a shackle arm member swingably mounted upon a fixed portion of the vehicle at one end thereof and swingably mounted upon a movable portion of the vehicle at the other end thereof. The brake control apparatus fixedly mounted upon the shackle arm member includes a main body, an inlet port fluidically communicated with a master brake cylinder, an outlet port fluidically communicated with the wheel brake cylinders, and a valve member interposed between the inlet and outlet ports for controlling the fluid pressure from the master cylinder to the wheel brake cylinders by sensing a predetermined magnitude of deceleration generated in accordance with the load weight of the vehicle when the vehicle is braked thereby obtaining the most effective braking force within the system which will nevertheless not cause slippage or skidding of the vehicle regardless of the change in the load weight.

Abstract: A valve device for use in liquid pressure vehicle braking systems to control rear brake pressure comprises a plunger in a cavity in a housing, the cavity being closed at one end. The plunger has a land which slides within a portion of the cavity. The area of the plunger that is exposed to liquid pressure at the closed end of the cavity is greater than the area of the plunger that is exposed to liquid pressure on the other side of the land. A passage through the land is inclined to the axis of the plunger. A valve unseating pin in the inclined passage co-operates with a frusto-conical surface of the cavity to unseat a ball in the inclined passage. A biassing spring surges the plunger towards the closed end of the cavity against the action upon the plunger of rear brake pressure which acts upon the larger presented area portion of the plunger. Liquid pressure is transmitted from the master cylinder to the rear brake operating motor cylinders when the ball is unseated and not when the ball is seated.

Abstract: The brake force regulator device is for a dual circuit brake system in which the function of the regulator is suppressed if an uncontrolled brake circuit fails. A locking piston is provided which serves this purpose as well as at the same time to release a differential pressure warning signal should one of the two circuits fail. The advantages achieved with the arrangement disclosed are that only a small amount of pressure fluid is drawn from the intact brake circuit in case of the failure of the other circuit so that the locking piston performs a dual function.

Abstract: A hydraulic brake pressure control valve includes a first pressure chamber connectable with a source of hydraulic pressure such as a master cylinder, a second pressure chamber connectable with a rear wheel brake cylinder, a fluid passage for communicating the pressure chambers with each other, and an inertia valve for preventing communication through the fluid passage when deceleration of the vehicle exceeds a predetermined value. The control valve further includes a plunger slidably disposed in a bore, the opposite ends of which are exposed to hydraulic pressure in the first and second pressure chambers respectively. A piston is slidably disposed in a bore and has one end which is exposed to hydraulic pressure in the first pressure chamber and another end which is exposed to atmospheric pressure or gas pressure.

Abstract: Caliper type bicycle brakes for the front and rear wheel are actuated simultaneously by a single actuator assembly mounted adjacent the handlebar. Hydraulic fluid under pressure is delivered to the brakes through two self-contained hydraulic circuits, one for the front brake and one for the rear brake. The brake system includes a device for applying a greater braking force at the front wheel than at the rear wheel. In an alternate embodiment the brake system is actuated by the chain drive system of the bicycle. Improved brake shoe elements and a device for wiping water from the wheel rim for enhanced wet weather braking are also disclosed.

Abstract: A fluid pressure operated vehicle braking system includes a control valve assembly comprising an inlet and outlet, a normally-open valve having a valve member movable in response to a predetermined inlet pressure to control the flow of pressure fluid between the inlet and the outlet, and a stepped piston subjected to a biasing force dependent upon the vehicle loading and operable in response to both the inlet pressure and the biasing force to reduce the outlet pressure after the predetermined inlet pressure is attained.

Abstract: A load responsive proportioning valve for use on a vehicle having a source of hydraulic fluid and front and rear wheel hydraulically actuated brake systems, the assembly including proportioning valve means in one of the brake systems actuatable to modulate the brake pressure in that one system to provide for a reduced brake effect at the rear brake wheels relative to that of the front wheels to compensate for weight transfer during braking, the proportioning valve means including a piston member movable between positions opening and closing a flow path from the fluid source to the one brake system, bias means including a fluid spring providing a force to move the piston member toward one of the positions, and deceleration sensing means for controlling the magnitude of the fluid spring as a function of variations in the magnitude of deceleration of the vehicle, whereby the modulating effect of the proportioning valve means compensates for variations in loading of the vehicle.

Abstract: A dual hydraulic brake system incorporating a dual master cylinder for separately pressurizing the front and rear brakes of a vehicle. A pressure limiting device is positioned in the brake system for the front wheels which have disc-type brakes. The device prevents the front brakes from being energized until the rear drum-type brakes are functioning and then proportions the pressure applied to the front brakes. Also, an apparatus for providing an indication to the operator of failure of either the front or rear brakes, which apparatus will automatically reset itself upon correction of the failure, is positioned adjacent the pressure limiting device and is responsive to fluid pressure in both systems.

Abstract: Apparatus for controlling a two-circuit brake system for motor vehicles with the aid of a controllable pressure reducing valve which reduces the pressure in the rear wheel brake circuit compared to that in the front wheel brake circuit and which includes a by-pass line between the pressure inlet from the master cylinder and the pressure connection to the rear wheel brakes which is controllable by a solenoid valve; the brake slippage at the front and at the rear wheels is thereby measured, the thus-obtained values are compared with each other, and the solenoid valve is then controlled by a pulse sequence as long as the brake slippage at the front wheels is larger by a predetermined value than that at the rear wheels.

Abstract: A fluid pressure device usable in a vehicle brake system which includes a dual master cylinder inserted into two mutually independent fluid lines which are connected between the front and rear wheel brakes. The device is arranged across the fluid lines between the brake master cylinder and the rear wheel brakes and includes a pair of differential pistons slidably accommodated in a cylinder bore and a balance piston slidable in the bore between the differential pistons, a pair of input fluid chambers being defined between the balance piston and the differential pistons and connected with respective upstream portions of the fluid lines while a pair of output fluid chambers are defined on the outer sides of the differential pistons and connected with the adjacent input fluid chambers through fluid control valves and with respective downstream portions of the fluid lines.

Abstract: A pressure control valve for a braking system having separate pressure circuits comprises a control member movable to control communication between an inlet and an outlet for connection in one of the circuits and spring biased to a valve open position. The control member has an extension which passes sealingly into a space between and sealed from the two circuits and which engages a piston subject to the pressure in the other circuit. The piston is separate from the control member and is operable under the pressure in that other circuit to overcome the spring bias and close the valve by displacing the control member.

Abstract: A braking pressure limiter device in which an inertia responsive valve normally closes under deceleration of the vehicle but has its closing action impeded by a linkage connected to an anti-roll bar so as to be responsive to the loading of the vehicle, for example the vehicle suspension to sense loading of the rear axle.

Abstract: In a brake system including two independent hydraulic lines extending from a dual type brake master cylinder and connected to the respective rear wheel brakes, a novel pressure control device provided for automatically adjusting the ratio of the front to the rear wheel brake pressure for maximized overall braking efficiency and including failure alarm for warning the driver of any trouble in operation of the device or of any fluid leakage on the hydraulic lines without delay. The device includes a cylinder bore fitted with a pair of annular pistons and a balance piston extending axially therethrough. A pair of sealing rings are mounted on the balance piston at the opposite ends thereof to define each an input and an output hydraulic chamber, respectively connected with the upstream and downstream portions of the associated one of the two hydraulic lines and adapted to be placed in communication with each other with displacement of the balance piston from its neutral position.

Abstract: A motor vehicle hydraulic brake system includes a front brake circuit and a rear brake circuit. The rear brake circuit includes a blend back proportioning valve which controls the pressure in the rear brake circuit. The blend back proportioning valve includes a proportioning piston which cooperates with a valve seat to maintain increases in rear brake pressure proportional to but less than increases in master cylinder pressure between a first predetermined pressure and a second predetermined pressure. A blend back spool moves the valve seat away from the proportioning piston to equalize master cylinder pressure and rear brake pressure when the second predetermined pressure is reached.

Abstract: A reducing valve which performs proper vehicle braking control in proportional response to the load being carried on the vehicle by sealing off a hydraulic braking pressure, which is regulated to be proportional to the load on the vehicle, in a control chamber through the use of a control valve for the control of the pressure reducing function of the reducing valve. The control valve is regulated to remain open, in opposition to the applied hydraulic pressure from the braking pressure source, in proportion to the increase of vehicle load thereby correspondingly raising the reduction starting pressure of the reducing valve which reduces the braking hydraulic pressure to the rear wheel brakes of the vehicle.

Abstract: A motor vehicle air brake system which includes a blend back proportioning valve which reduces brake sensitivity at low braking pressures and which allows full braking at high braking pressures. The proportioning valve includes a shuttle piston, a blend back sleeve, and a one-piece outlet diaphragm. The outlet diaphragm seals a reference chamber from outlet pressure and permits movement of the shuttle piston and blend back sleeve together as well as movement of the shuttle piston and blend back sleeve relative to one another. The proportioning valve also includes a one-piece inlet diaphragm which seals the reference chamber from inlet pressure and which provides a valving surface to open and close communication between the inlet and the outlet of the valve. In a second and third embodiment of the proportioning valve, springs are added to alter the proportioning characteristics of the valve.

Abstract: A load-dependent two-circuit brake for vehicles, especially for trucks, busses or the like which includes a load-dependent control valve arranged in the first brake circuit containing the rear-wheel brakes while another control valve is coordinated to the second brake circuit containing the front wheel brakes which has a predetermined transmission ratio and which is adapted to be acted upon by the control pressure in the first brake circuit in such a manner that the transmission ratio is adapted to be changed in the same sense as the control pressure in the first brake circuit.

Abstract: A combination proportioner and a shuttle piston which when moved actuates a brake pressure loss warning switch. A proportioner piston has a spring preload which must be overcome by rear brake supply pressure before the proportioner is actuated. Upon brake release the lips of the switch actuating piston proportioner seal act as a valve to relieve rear brake pressure to the pressure at which the proportioner began to operate. The proportioner is deactivated upon front brake system pressure loss. The proportioner mechanism is so assembled that it can be utilized as an original installation or as a replacement module. In an installation where no proportioning action is required, the shuttle piston and head nut are installed without a proportioning valve. When a proportioning valve is required, a head nut with the proportioning mechanism preassembled therein is installed.

Abstract: A brake pressure limiting device is disclosed for use in a dual-circuit vehicle brake system. The device comprises two valve bodies arranged on a common axis. Each valve body has one inlet for connection with a master brake cylinder and at least one brake line outlet. The pressure at the outlet can be isolated from that at the inlet by a valve element which is axially movable within the valve body between an open and a closed position. Movement of both valve elements in the two valve bodies is controlled by a common actuating member which causes the valve elements to close when the pressures at the valve body inlets exceed a limiting value that is a function of the vehicle load.

Abstract: A vehicle with at least front and rear sets of brakes includes a pair of brake control valves for normally communicating a source of pressurized fluid to individually control the brakes, a counterpart pair of inversion valves for normally supplying air piloting pressure to the brake control valves, and a retarding valve system communicating a source of pressurized air at one value to one inversion valve and at a proportionately lower pressure to the other inversion valve so that one set of brakes absorbs less energy than the other set of brakes in a retarding mode. The brake control system also includes a service brake valve actuatable to delivery equal pressure to both inversion valves for absorbing equal energy in both sets of brakes in an overriding manner with respect to the retarding valve system.

Abstract: A load sensitive proportioning valve for an automotive vehicle having a source of hydraulic fluid and front and rear hydraulically actuated brake systems, the proportioning valve being operable to modulate the brake pressure in one of the brake systems to provide for a reduced brake effect at the rear wheels relative to that at the front wheels to compensate for the weight transfer during braking, the valve including a modulating piston movable between positions opening and closing a flow path from the fluid source and the one brake system a first bias producing element for providing a force to move the piston element as a function of the magnitude of the deceleration of the vehicle, and a second bias producing element providing a force to move the piston in response to the fluid pressure of the one system and the modulated fluid pressure of the proportioning valve, whereby the modulating effect of the proportioning valve compensates for variations in loading of the vehicle.

Abstract: A brake valve for a motor vehicle brake system is interposed in the brake line between the master cylinder and the rear wheel brakes and is constructed to limit the fluid pressure at the rear brakes relative to the pressure at the front brakes during the application of master cylinder pressure. Pressure is limited at the rear brakes for the purpose of balancing the front and rear brakes in accordance with their relative effectiveness. The valve includes an inertia sensor that senses the rate of vehicle deceleration and modulates the pressure ratio between the front and rear brakes accordingly. The valve mechanism with its inertia sensor provides a device for compensating for the amount of load carried by the vehicle which, in turn, affects the relative effectiveness of the front and rear brakes.

Abstract: A motor vehicle hydraulic brake system includes a front brake circuit and a rear brake circuit. The rear brake circuit includes a blend back proportioning valve which controls the pressure in the rear brake circuit. The blend back proportioning valve includes a proportioning piston which cooperates with a valve seat to maintain increases in rear brake pressure proportional to but less than increases in master cylinder pressure between a first predetermined pressure and a second predetermined pressure. A blend back spool moves the valve seat away from the proportioning piston to equalize master cylinder pressure and rear brake pressure when the second predetermined pressure is reached.

Abstract: A load responsive pressure modulating valve device for use in a brake system of a vehicle is so constructed that the starting pressure for the pressure modulating operation is controlled by a specific valve operated by a partial pressure of the input hydraulic brake pressure. The device is capable of distributing the hydraulic brake pressure corresponding to a transient weight transfer from rear wheels of the vehicle to front ones caused by the braking operation, to the front and rear brakes by varying the starting pressure in response to load and deceleration of the vehicle.

Abstract: This invention relates to automobile braking systems of the kind that employ a device for limiting braking pressure and intended particularly for systems which have separate supply circuits for the front and rear-wheel brakes. Such limiting devices conventionally comprise a limiter body which has an inlet orifice and an outlet orifice with a valve mounted therein for cutting off the inlet orifice from the outlet orifice, a movable piston subject to the hydraulic pressure at the inlet orifice, an inertial mass which is capable of movement with respect to the body, load-sensitive means and elastic means for co-operation with the inertial mass and the piston.

Abstract: A brake valve for a motor vehicle brake system is interposed in the brake line between the master cylinder and the rear wheel brakes and is constructed to limit the increase in fluid pressure at the rear brakes relative to the increase in pressure at the front brakes during the application of master cylinder pressure. Pressure is limited at the rear brakes for the purpose of balancing the pressure between the front and rear brakes in accordance with the relative effectiveness of those brakes. The valve includes an inertia sensor that senses the rate of vehicle deceleration and modulates the pressure ratio between the front and rear brakes. The valve mechanism including its inertia sensor provides a device for compensating for the amount of load carried by the vehicle which, in turn, affects the relative effectiveness of the front and rear brakes.

Abstract: A device for varying the proportion of brake pressure delivered to the front and rear brakes of a vehicle, and including a differential area piston for decreasing the proportion delivered to the rear brakes between the first and second inlet pressures, and an additional valve assembly actuatable in response to a predetermined pressure differential between the fluid pressure delivered to the piston and the fluid pressure delivered thereby to the rear brakes so as to establish a decreasing pressure differential between the pressure delivered to the front and rear brakes.

Abstract: A motor vehicle air brake system includes a blend back proportioning valve which reduces brake sensitivity at low braking pressures and which allows full braking at high braking pressures.