Abstract: A vehicle brake system, with the usual arrangement of a power booster axially aligned with the brake master cylinder piston and engaged between it and the brake pedal, has a fluid pressure differential-operated actuator offset from the conjoint axis of the power booster and the master cylinder piston. The actuator is coupled to the master cylinder piston through a mechanical linkage which provides a substantial mechanical advantage. The actuator causes the brakes to be applied independent of the brake pedal in response to any of several sensed conditions which dictate that the vehicle should not be moving.

Abstract: A pusher comprises a body with a plurality of piston holes provided on a front surface thereof, pistons slidably fitted to the piston holes and each having a front end extending in front of the body, an oil passage provided in the body and communicated with a bottom portion of each piston hole, a pressure chamber provided in the body and communicated with the oil passage, a threaded shaft threadably fitted to a threaded hole which is provided in the body and communicated with the pressure chamber, and oil filled in the bottom portion of each piston hole, the oil passage and the pressure chamber, where the piston is adapted to be pushed in front of the body by the threadable advancing of the threaded shaft at force larger than the advancing force of the threaded shaft.

Abstract: A brake system wherein an input from an operator operates a first master cylinder (12) produces first and second hydraulic fluid pressures. Flexible conduit (22 and 24) carries the first and second hydraulic fluid pressures to an actuator (26) for a hydraulic power booster (28). A plunger (58) in the actuator (26) reacts either to the first hydraulic fluid pressure or the second hydraulic fluid pressure by moving to operate the hydraulic power booster (28). Operation of the hydraulic power booster (28) provides an input force to develop first and second operation fluid pressures in a second master cylinder (30) to effect a brake application.

Abstract: A brake unit for a road vehicle with a hydraulic dual-circuit brake system having two master cylinders, the brake booster and elements for antilock and/or propulsion or slip control in a common housing. A brake booster drive cylinder which can be subjected to the outlet pressure, proportional to the pedal travel, of a brake valve, is arranged between static master cylinders. Coupled to the piston of the drive cylinder is a pivotable rocker, the arms of which are each supported on one of the master cylinder pistons via tappet. Assigned to at least one of the master cylinders is a regulating cylinder having an opposed piston which can be supported on the piston of the master cylinder and which, when subjected on one side to the outlet pressure of the auxiliary pressure source of the brake booster, causes the piston of the master cylinder to be returnable towards its basic position counter to the actuating force exerted on it.

Abstract: The subject of the invention is a control device (10) for a twin master cylinder of the type with two master cylinders positioned parallell to one another and side by side, the device (10) being capable of being positioned between an actuating pedal and the pistons of the masters cylinder, the device (10) incorporating a control rod (44) which is capable of being connected to the pedal and two pushrods (28, 28') which are each capable of acting upon one of the pistons, the pushrods (28, 28') being guided so as to slide parallel to the axes of the master cylinders. According to the invention, the control rod (44) cooperates with the push rods (28, 28') through levers (52, 54) each of which is hinged at one end (56, 58) to one of the rods (28, 28') and is pushed so as to bear at the other end (64, 66) upon a bearing surface (62, 60) of the other rod (28', 28) by means of a peg (80) which is firmly fixed to the control rod (44). Application to the braking systems of motor vehicles.

Abstract: An hydraulic circuit includes a master cylinder and at least one slave cylinder connected in series circuit. An auxiliary discharge conduit with a solenoid-actuated valve is provided to selectively permit the master cylinder to extend its full useful range after the slave cylinders are fully extended. Under normal operation the valve is closed so that the cylinders may extend together. When the slave cylinders reach full extension, the main control valve is kicked out of its detent and the system locks up in that position. If the operator wants the master cylinder to extend further to a second limit position, he opens the solenoid-actuated valve and again operates the main control valve to extend the master cylinder. The system insures that the main control valve will be released from the detent position when the slave cylinder is fully extended at the first limit position of the master cylinder.

Abstract: An actuator for variable adjustment of the pistons in hydraulic slave cylinders for regulation of for example the elevation adjustment of work stations. The pistons are actuated by way of a pusher which is non-rotatable but axially displaceable in the actuator housing (10). In the housing (10) there are provided one or more oblong openings (22) for drivers (27) attachable to the pusher and arranged for cooperation with the corresponding pusher in one or several further actuators placeable close to the actuator and that in at least one of the connected actuators there is arranged a threaded spindle for cooperation with a pusher designed as a nut.

Abstract: On actuation, each pressure generator at each of a plurality of locations along a conduit develops a pressure rise in the conduit to energize a pressure sensitive device in fluid communication with the conduit. Each pressure generator includes a bulbous member which expels a quantity of fluid (air) into the conduit when depressed and a valve for segregating the volume defined by the bulbous member from the conduit except when the bulbous member is depressed to minimize dissipation by a nonactuated pressure generator of the pressure rise within the conduit and generated by another actuated pressure generator.

Abstract: Control device (10) for a twin master cylinder (18) of the type with two master cylinders situated side by side and parallel to one another; the device (10) is capable of being positioned between an actuating pedal (12) and pistons (26, 26') of the master cylinders. According to the invention the device (10) incorporates a compensation (63, 63') of the travel of a control rod (52) situated on the same side as the pedal (12) relative to the travel of two independent push rods (34, 36') which are capable of acting upon each of the pistons (26, 26').

Abstract: A hydraulic brake booster including, master brake cylinder pistons disposed in telescoping fashion in a short housing structure, and a locking piston for the brake pedal actuation is disposed parallel to the master brake cylinder in axial alignment with the travel simulator and a brake valve. A further parallel disposition of an adjusting piston is acted upon by reservoir pressure and in which the master brake cylinder pistons are supported in a slidably displaceable manner.

Abstract: A brake system for automotive vehicles is equipped with devices for the electric control of the brake force distribution and/or for the control of slip. The front wheels are connected to a pedal-actuated braking-pressure generator (1). In contrast thereto, the rear wheels (HR, HL) are acted upon with braking pressure by virtue of a braking pressure generator unit (5) which is composed of a vacuum servo unit (6) and a master cylinder (7) and which is actuated by a multidirectional control valve (4), such as a three-way/three-position rotary spool valve. The switch position of the valve (4) is responsive to the electric output signals of an electronic combining circuit (17, 17') which is, by way of wheel sensors, furnished with information about the rotational behavior of the wheels and the output of which circuit is electrically connected to the drive (19) of the three-way/three-position rotary spool valve (4).

Abstract: A hydraulic system for lifts provided with two independently supported parallel platforms comprises at least two cylinder-piston units (80, 81) for raising the platforms, a metering device (7) for feeding identical quantities of fluid to said two units, and a balancing device (74, 75) operated by means (31, 32) for measuring the height difference between the platforms and arranged to feed a quantity of supplementary fluid to that cylinder-piston unit (80) or (81) operating the lower platform by withdrawing it from that cylinder-piston unit (81) or (80) operating the higher platform.

Abstract: Control device (10) for a twin master cylinder (18) of the type with two master cylinders situated side by side and parallel to each another; the device (10) being capable of being positioned between an actuating pedal (12) and pistons (26, 26') of the master cylinders. According to the invention the device (10) incorporates a twin beam (36) ensuring balancing of the forces applied to each of the pistons (26, 26') while ensuring the rigidity of the control device (10), and the twin beam (36) incorporates a device for maintaining the separation of the points of application (32, 32') of the forces on the pistons (26, 26').

Abstract: A driving apparatus for producing a to-and-fro movement and having four plunger cylinders and four external non-return valves. Such driving apparatus is distinguished by a particularly simple construction.

Abstract: A master cylinder reservoir for use in a tractor hydraulic braking system has a pair of separate compartments, each adapted for connection to a respective one of a plurality of pressure cylinders. The compartments are interconnected by a flexible connector such as a convoluted tube, and the reservoir is advantageously made in a single piece by blow molding enabling the relative positions of the cylinders to vary so that the reservoir can be readily mounted by spigots engaging bores in the cylinders. The reservoir also has a flanged rigid tubular connection component molded into it during the reservoir molding operation, the material of the reservoir closely surrounding opposed surfaces of a flange of the component to resist longitudinal withdrawal of the component.

Abstract: A hydraulic booster including an input piston adapted to be actuated by a manually operated member such as a brake pedal. The input piston is axially slidable in a power piston which is in turn axially slidable in a booster casing. The power piston divides the inside cavity of the casing into a power chamber and a reservoir chamber. An electrically operated plunger pump is provided and has an outlet port connected with the power chamber and an inlet port. Between the input piston and the power piston, there are defined a first valve and a second valve. The first valve functions to open the power chamber to the reservoir chamber when the pedal is released but to disconnect the power chamber from the reservoir chamber when the input piston is depressed by a first predetermined distance.

Abstract: A dual-circuit master cylinder having hydraulic equalization is disclosed including a casing having two parallel bores and elongated pistons defining two power chambers in the casing connected to wheel brakes, a yoke including two blind bores receiving extending portion of the pistons defining two equalization chambers, an auxiliary piston operatively connected to the yoke, and a brake actuating member defining an auxiliary chamber connected to a supply reservoir via a check valve for supplying equal pressurized fluid to the equalization chambers upon movement of the auxiliary piston and yoke to displace the power pistons.

Abstract: A brake booster includes a housing with at least three bores to movably carry a pair of pistons and a valve assembly. A diaphragm is exposed to a fluid pressure differential to pull the pair of pistons and the valve assembly to a brake applied position wherein braking fluid pressure is generated in all three bores.

Abstract: A hydraulic brake booster including main cylinders operative relative to a pedal stroke by which a sufficient pedal stroke is still available in the event of a failure in the pressure supply so that the brakes can be actuated by the pedal stroke and furthermore flooring of the brake pedal is avoided in the event of failure of the fluid medium power supply.

Abstract: A brake booster (16) includes a pair of pistons (50, 56) and a valve assembly (74) operable to communicate fluid pressure to the pair of pistons (50, 56). An input assembly (90) moves in response to an input force to control the operation of the valve assembly (74). Movement of the valve assembly (74) allows fluid to be supplied to working chambers (52, 58). Resilient means (133, 135) acts on and holds pins (130, 132) against the pistons (50, 56). When the fluid pressure in the working chambers (52, 58) acting on the pins (130, 132) is sufficient to overcome the resilient means (133, 135) an increase in the fluid pressure in chamber (52, 58) moves the pins (130, 132) into engagement with the input assembly (90) to oppose movement of the input assembly (90) since a desired brake force has been generated.

Abstract: The actuator (12) comprises three main parts, an outer casing (20), a movable piston (28) and a fixed piston (36). A stepped outer portion (50, 52, 54) of the movable piston (28) cooperates with a stepped cavity (40, 42, 44) in the casing (20) to define a plurality of concentric, variable diameter fluid chambers (1, 2, 3) bounded at their ends by radial surfaces on the movable piston (20) and within the casing cavity. The movable piston (20) and the fixed piston (36) define a plurality of axially spaced apart variable diameter fluid chambers (1', 2', 3') which are bound on their ends by radial surfaces on the fixed piston (36) and radial surfaces within the cavity formed in the movable piston (20). One set of the chambers (1, 2, 3) is connected to supply pressure (P.sub.S) and the second set of chambers (1', 2', 3') is connected to return pressure (P.sub.R). Seal receiving grooves are formed in outer surface portions of the fixed and movable pistons (28, 36). Seal rings (S.sub.

Abstract: Two separate hydraulic master cylinders are connected with pressure lines to the front and rear brake cylinders. These two master cylinders are mechanically connected together by an articulating balance bar, all of which is mounted on a slidable mounting bracket. The mounting bracket is slidably movable by a reversible electric motor driving a worm gear that is connected to the mounting bracket. The relative position of the mounting bracket on its mounting plate in relation to the input point of a push rod determines the proportioning ratio of the two master cylinders. The assembly may be moved to obtain any proportioning ratio from 100% front brake to 100% rear braking.

Abstract: The present invention relates to a device for actuating an automatic device comprising a plurality of combined mobile members, wherein this device comprises an electric motor actuating a hydraulic master jack which in turn actuates a plurality of hydraulic slave jacks connected to said mobile members.

Abstract: The present invention relates to a dual-circuit hydraulic brake system with slip control, in particular for automotive vehicles, wherein wheel brakes (26, 27, 41, 42) are connected via electromagnetically actuatable multiple-position valves (38, 39, 88, 40, 24, 89) to brake circuits which are hydraulically isolated from one another, wherein the brake circuits are adapted to be pressurized by a tandem master cylinder (1), on the one hand, and are connectible to a dual-circuit pump aggregate (76, 77) adapted to be driven electromotively, on the other hand. Both outlets of the pump aggregate (76, 77) are connected to normally closed brake valves (43, 44) which are governed by the master cylinder pressure and separating valves (11, 12) which are adapted to be closed by the outlet pressure of the brake valves (43, 44) are inserted into the connections between the tandem master cylinder (1) and the wheel brakes (26, 27, 41, 42).

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: A brake system includes a brake booster coupled to a front wheel brake cylinder. The brake booster substantially defines a pair of rear wheel brake cylinders separate from the front wheel brake cylinder so that a pair of diaphragms are separated during braking to generate a power assist for the front and rear brake cylinders. A control valve cooperates with the brake booster to alter the power assist for the rear brake cylinders in response to a signal from an electronic control unit.

Abstract: A hydraulic system is disclosed which provides automatic proportional actuation of pairs of hydraulic cylinders. The proportioning mechanism comprises one or more standard hydraulic cylinders.

Abstract: In a master cylinder assembly separate master cylinders are connected by a common transfer passage through which the pressure spaces of the master cylinders in advance of pistons are in communication when the master cylinders are operated simultaneously, and communication between the pressure spaces is cut off by a transfer valve mechanism when one of the master cylinders is operated on its own. Each piston is guided to slide in its respective bore only by the sliding engagement with the bore of a guide portion of the piston and the guide portion is disposed on the outermost side of a transfer port with which the transfer passage is in communication when the piston is in a retracted position.

Abstract: The piston of an hydraulic master cylinder is guided to slide in portions of a bore in a body on opposite sides of a port in the wall of the body by a guide portion of the piston which is disposed on the outermost side of the port and by a cylindrical, axially extending, guide part at the outer end of a radial flange on a retainer. The retainer is mounted on an extension at the inner end of the piston and forms an abutment for a return spring for the piston.

Abstract: A hydraulic fluid circuit for use in an anti-lock braking system of a vehicle includes a relieved hydraulic fluid chamber of a hydraulic pressure modulator and a reservoir of a master brake cylinder which are operatively connected with each other by way of a hydraulic fluid line. Hydraulic operating fluid existing in the relieved hydraulic fluid chamber is relieved into the reservoir. The reservoir of the master brake cylinder is disposed at a position higher than the level of the suction joint or inlet of the relieved hydraulic fluid chamber of the hydraulic pressure modulator.

Abstract: A power brake unit for automotive vehicles comprising a valve adapted to meter fluid from an energy source into a booster chamber to act upon a booster piston arrangement. The booster piston arrangement includes a first booster piston and a second booster piston with the second booster piston being inoperative in the event of failure of the energy source. If the energy source fails, the pedal force is directly and mechanically transmitted from the brake pedal to the master cylinder piston via the first booster piston.

Abstract: In a master cylinder assembly comprising two pedal-operated master cylinders, each master cylinder comprises a pedal-operated piston of stepped outline working in a complementary stepped bore in a housing and having an inner end of smaller area carrying a first seal and an outer end of greater area carrying a second seal, a pressure space in the bore in advance of the inner end of the piston, a quick-fill chamber defined in the bore between the inner and outer ends of the piston, a normally-open recuperation valve providing communication between a reservoir for fluid and the pressure space at least when the piston is in a retracted position, and a normally-closed pressure-limiting valve assembly between the quick-fill chamber and the same or a second reservoir.

Abstract: An improved system for finely and precisely controlling the operational position of a glass electrode, micropipette, micro surgical knife or the like with the aid of hydraulic remote control devices including hydraulic hoses is disclosed. This system includes a control stand with an actuator assembly firmly mounted thereon, said actuator assembly comprising X-, Y- and Z-coordinate actuators, a first fine adjusting device for roughly adjusting the X- and Y-coordinate actuators and a second fine adjusting device for adjusting the Z-coordinate actuator and moreover finely adjusting the X- and Y-coordinate actuators. A glass electrode or the like to be finely located is adjustably mounted on the actuator assembly.

Abstract: In a dual master cylinder assembly comprising two independently and simultaneously operable master cylinders, primary pressure spaces between primary and secondary pistons are interconnected by a pipe-line, and secondary spaces between the secondary piston and adjacent ends of the master cylinders are connected to a common auxiliary braking system through a pipe-line. Each secondary piston is provided with an arrangement of passages in communication at all times with a reservoir for fluid, and normally open primary and secondary recuperation valves provide communication between the passages and the respective pressure spaces when the pistons are in their retracted positions. Simultaneous operation of both master cylinders causes both pairs of primary and secondary recuperation valves to close followed by pressurization of the fluid in both pairs of primary and secondary pressure spaces, whereby to apply simultaneously the brakes on opposite sides of the vehicle and to operate the auxiliary braking system.

Abstract: The invention relates to an intensifier using liquid, comprising at least one cylinder which has plural pistons and a lubricating chamber between them.

Abstract: A fast-fill master cylinder (14) includes a housing (26) defining a bore (38) therein having a portion (y) thereof of substantially constant diameter. A primary piston (54) is movably received in the bore portion (y) and a secondary piston (56) is movably received in the remainder of the bore (38). The secondary piston (56) cooperates with the housing (26) to define a secondary variable-volume chamber (62). The primary piston (54) cooperates with the housing (26) and with the secondary piston (56) to define aprimary variable-volume chamber (58). The primary piston also cooperates with the housing to define a constant-volume recess (84) circumscribing the piston (54). An annular partition member (94) circumscribes the piston member (54) within the recess (84) to divide the recess (84) into a pair of variable-volume compartments (108, 110). A bore 120 communicates the one compartment (110) with the primary chamber (58).

Abstract: An applied pressure or volume change is intrinsically transformed into an output pressure or volume change which is related to the magnitude of the relative input quantity and a ratio of effective areas of pressure application surfaces of a plurality of pistons in a fluidic transformer. The surfaces of the pistons are interconnected by fluid communication paths in a predetermined manner such that pressures existing in each of the communication paths relate only to the input pressure relative to the reference pressure and a ratio of the effective surface areas of the pistons, and such that the pistons are in a balanced force equilibrium state. The pressures present in the communication paths can be operatively applied on opposite sides of fluid sealing elements of a plurality of sealing elements arranged in serial order to operatively seal between the applied pressure and the reference pressure.

Abstract: According to the invention, the braking system includes two tandem master cylinders (100, 200), the first (100) having a first pressure chamber (110) connected to the left brake (132) of the tractor and a second pressure chamber (112) connected to the trailer brakes (300), and the second having a first pressure chamber (210) connected to the right brake (232) of the tractor and a second pressure chamber (212) likewise connected to the trailer brakes (300). The invention may be utilized with certain vehicles, in particular agriculture tractors.

Abstract: A master cylinder device for controlling the pressure of hydraulic braking fluid in two separate braking circuits of a hydraulic braking system includes a housing having two parallel and co-extensive pressure chambers each movably accommodating one master piston. A pressure element transmits the brake pedal force to one of the master pistons to pressurize the fluid present in a first pressure compartment and thus in the associated first brake circuit. A part of the thus pressurized fluid is diverted to an actuating compartment of the other pressure chamber to act on the other master piston and thus to pressurize the fluid present in the second pressure compartment and in the associated other brake circuit. When elevated pressure fails to develop in the first pressure compartment, the pressure element engages a tappet of the other master piston to mechanically displace the same in the actuating direction and thus to pressurize the fluid supplied to the other brake circuit.

Abstract: An apparatus that controls movement of an arm through a gaseous or liquid fluid. The apparatus incorporates a plurality of longitudinally extensible hose members that expand and contract their respective lengths responsive to introduction and withdrawal, respectively, of hydraulic fluid thereinto and therefrom. The hose members are interconnected to one another through a plurality of longitudinally spaced, transversely disposed brace members that may serve as lever means so that expansion or contraction of one hose member can effect an opposite response in an opposed member. The brace members may be interconnected by a spine means that coincides with the longitudinal axis of symmetry of the apparatus. A sheath covers the apparatus. The arm has applications in the field of robotics and a special rat tail-like form of the apparatus provides a low drag substitute for conventional aircraft rudder and elevator assemblies.

Abstract: A hydraulic master cylinder has pistons displaceable along the pivot axis of a brake pedal to apply the vehicle brakes. Motion between the pedal and the pistons is transmitted by balls located in a respective arcuate track formed partly in the pedal and partly in the respective piston. The master cylinder is particularly suitable for dual circuit brake systems. A master cylinder having a single piston is also disclosed.

Abstract: In a vehicle braking system of the kind in which brakes mounted on opposite sides of the vehicle are associated with respective pedals (1) and can be operated together for normal vehicle retardation or independently to assist vehicle steering, the brakes are connected to respective chambers (14, 15) of a tandem master cylinder (5) through respective control devices (7) which are actuated by the pedals (1) and control communication between the respective chambers (14, 15) and a reservoir.

Abstract: An oscillating coolant pump includes a pair of opposed bellows mounted to reciprocate in a housing for moving a volume of fluid through a heat exchanger and an electronics package. The pump functions without the use of check valves.

Abstract: A master cylinder assembly comprising two separate master cylinders is disclosed. Pressure spaces of the master cylinders are interconnected through outlet passages and a transfer passage, and a transfer valve is housed within each outlet passage. When the master cylinders are inoperative both transfer valves are retained by yieldable spacers in intermediate positions in which a limited flow can take place through both valves in both directions. This prevents hydraulic fluid from being trapped in the transfer passage which otherwise might cause a fracture to occur upon expansion with temperature of the fluid. Each transfer valve comprises a valve member which is engageable with a seating. The yieldable spacers by which the valve members may be held away from the seatings may be the thickness of a film of hydraulic fluid therebetween.

Abstract: A master cylinder includes a housing (18) with a pair of pistons (60, 64) operable to pressurize a pair of pressure chambers (66, 72). One (64) of the pair of pistons includes means (76, 80) to control communication from a reservoir (34) to both pair of pressure chambers (66, 72).

Abstract: In a tandem type brake master cylinder having a body formed with coaxial large and small cylinder bores, a first piston member having a large land sliding in the large bore and a first small land sliding in the small bore, a second piston member having second and third small lands sliding in the small bore, a first chamber defined between the large land and the first small land, a second chamber defined between the first and the second small lands, a third chamber defined between the third small land and a closed end of the small bore, a first spring biasing the first and second piston members apart, a second spring biasing the second piston member away from the closed end of the small bore, first and second outlets opening from the second and third chambers respectively, and a means to allow fluid to pass from the first chamber to the second chamber but not back, a means is provided to prevent the first piston member and the second piston member from becoming separated by a distance greater than a certain pr

Abstract: A brake booster (16) includes a housing (26) with a plurality of parallel bores (38, 40, 42). A first piston (50) is disposed in the bore (38), a second piston (56) is disposed in the bore (40) and a valve assembly (74) is disposed in the bore (42) to control communication of fluid pressure to a pair of working chambers (52, 58) within the bores (38, 40). A pair of connecting pins (130, 132) cooperate with a plunger (100) to transmit a reaction force to a vehicle operator.

Abstract: In a master cylinder assembly the pressure spaces in advance of pedal-operated pistons of two separate master cylinders are interconnected by a transfer passage, and each master cylinder incorporates a boost chamber to which hydraulic fluid from a pressure source is admitted to act on the piston and augment the force applied to the piston by the pedal when the master cylinder is operated. Each master cylinder incorporates a control valve having a valve spool which is normally urged by a spring into a retracted position to close a transfer port providing communication between the pressure space and the transfer passage and to close an inlet port to cut-off communication between the pressure source and the boost chamber.

Abstract: A dual power brake booster assembly in which the hydraulic boost section is initially operated, the vacuum booster section is then operated to runout while the hydraulic section maintains a hydraulic boosted force level, the hydraulic section is then further operated to further increase the hydraulic boosted force as the vacuum booster section maintains the vacuum boosted force level attained by it at runout, and additional master cylinder actuation by additional manual force. The invention also includes the method of generating brake actuating pressure. The brake booster assembly may be operated only to the extent necessary to produce the desired amount of master cylinder actuation. The booster assembly will operate when the power source for one section is diminished or not available. It is also operable manually when pressure from neither power source is available.

Abstract: A master cylinder includes a sleeve (31) which defines fixed positions for a pair of seals (30, 32). A pair of pistons (36, 38) cooperate with the seals (30, 32) to form pressure chambers (40, 42) which communicate fluid pressure to brake circuits during braking. A bearing member (44) cooperates with one (36) of the pistons to define an auxiliary pressure chamber (50) and the bearing member (44) is provided with an additional passage (140) for communicating fluid into and out of the auxiliary pressure chamber as well as an end (46) directing movement of the one piston (36).