Abstract: A master cylinder (10) defines a housing (12) with a bore (14) receiving a first piston (32) and a second piston (34). A sleeve (50) disposed within the bore (14) cooperates with a plurality of seals (68, 70, 72) to balance the forces caused by fluid pressure acting against the inside of the sleeve (50) and the outside of the sleeve (50). The sleeve (50) is made from a lightweight plastic material.

Abstract: A shortened master-cylinder comprising longitudinal grooves on the inner surface of the bore of the cylinder and provided to allow permanent communication between a fluid pressure chamber and the corresponding fluid output.

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: A master cylinder includes a housing (30) with a stepped bore (32) receiving a sleeve assembly (50). A pair of pistons (80, 82) are disposed within the stepped bore (32) and one (82) of the pair of pistons defines portions of compensation passages between a reservoir (37) and a pair of pressure chambers (88, 90). The one piston (82) is movable to simultaneously control communication through the compensation passages.

Abstract: The master cylinder (10) comprises a seal cup (24) made from an elastomeric material assembled with axial and radial play around the head (18) of the piston (16). A stop ring (40) slidably received in the bore (14) permits to unseat the seal cup (24) from the shoulder (30) of the piston in order to connect the supply chamber (28) and the pressure chamber (26). When the piston (18) is displaced towards the latter, it displaces the stop ring (40) by the cooperation of two conical surfaces (54 and 56), the seal cup (24) being supported on a flat surface, composed of the radial shoulder (30) of the piston and the radial face 42 of the stop ring (40) substantially continuous.

Abstract: A master cylinder includes a housing (24) with a bore (26) receiving a pair of pistons (42, 48). The piston (48) engages seals (62, 64 and 66) to substantially define paths to a pair of pressure chambers (50, 52).

Abstract: This mechanism makes it possible to obtain in succession a fast approach stroke (C), and then a work stroke with a substantial developed stress, in operations such as riveting or marking, the work stroke being started as the tool (16) comes into contact with the part to be pressed (25). A control stem (4) and a body (9) are movable along one and the same axis (3), means such as a clack (31) providing for their non permanent locking. The stem (4) is integral with a primary piston (8) penetrating into a hydraulic circuit (10, 11) of the body (9); this circuit communicates, on the one hand, with an expansible casing (19) surrounding the body (9) and making it possible to block this body with respect to the frame (1), and on the other hand, with a chamber (12) in which a secondary piston (15), drawn back by a spring (18) and integral with tool (16), slides.

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: A brake master cylinder having a push rod including a body which includes resin material, a metal liner inserted within the body, a seal member disposed between the body and the metal liner, a piston slidably positioned within the metal liner and actuated by the push rod wherein the length of metal liner is slightly longer than the length of large diameter portion of the piston which is in contact with an inside wall of the metal liner plus a length defined by the range in stroke of the piston and a support member for securely holding the metal liner and limiting movement of the push rod.

Abstract: A master cylinder for hydraulically actuated brakes for automotive vehicles includes at least one master cylinder piston with a piston return spring anchored by a central clamping member and a valve body which is slidable relative to the master cylinder piston and which opens a compensating port in the master cylinder piston when the return spring is relieved. The valve body carries an elastic sealing element at its end face close to the compensating port. The outer diameter of the elastic sealing element is greater than the diameter of the compensating port. A pin shaped on the valve body extends through the sealing element and is adapted to plunge into the compensating port on approach of the valve body to the piston end surface which surrounds the compensating port, thus preventing the sealing element from penetrating into the compensating port.

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: 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: An apparatus for expanding tube ends in a tube sheet of a heat exchanger tube bundle comprises a mandrel which can be inserted into the tube end and an expansion pressure generator connected to said mandrel. A source of filling liquid is also connected to the mandrel to the expansion pressure generator which has a port for the filling liquid selectively blocked by the plunger of the expansion pressure generator so that problems with check valves for the filling can be obviated.

Abstract: A master cylinder is provided on the cylinder body with a reservoir-receiving mouth formed near the border of the section of of a large diameter and the section of a small diameter of a stepped bore, a through hole being formed between the bottom surface of the reservoir-receiving mouth and the first pressure chamber, a compensation hole being formed between the bottom surface of the reservoir-receiving mouth and the second pressure chamber, a valve seat fitted in and fixed to the reservoir-receiving mouth and having an internal hole formed therein, a check valve provided within the reservoir-receiving mouth between the bottom surface of the reservoir-receiving mouth and the valve seat with the valve element being pressed against a resilient member fixed to the valve seat by means of a spring, a projecting member protruding into the first pressure chamber through the through hole provided for the valve element coaxially with the valve element so that the valve element is titlted to form a passage between the

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: A master cylinder includes a housing (12) with a bore (14) receiving a pair of pistons (32, 34). A bearing (50) extends from the housing (12) to one of the pistons (32) to define a passage (65) communicating fluid to a pressure chamber (40). The bearing (50), the passage (65) and the pressure chamber (40) extend outwardly of the housing bore (14) to permit the length of the housing to be reduced.

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 reservoir assembly for a master cylinder includes a housing with a surface adapted to interface with the reservoir assembly. The reservoir assembly comprises a first part made from a lightweight plastic material and a second part made from a metallic material. The second part is adapted to fit on the surface while attachment of the reservoir assembly to the housing is provided for by the second part.

Abstract: A two-stage, hydro-pneumatic actuator suitable for use as a railway vehicle brake. The hydraulic cylinder comprises a large diameter bore in which a low- and a high-pressure piston operate jointly during a first stage of operation to effect a high volumetric displacement of hydraulic fluid via a small diameter bore in order to take up the clearance between the brake shoes and wheel. As the brake shoes contact the wheel, the high-pressure piston enters the small bore to interrupt further displacement of hydraulic fluid from the large bore. The force of the high-pressure piston alone during this second stage of operation produces the required brake forces with a high multiplication factor. Make-up fluid is drawn into a chamber on the backside of the low-pressure piston during a brake application stroke an amount corresponding to the over-travel of the high-pressure piston and is subsequently discharged into the hydraulic cylinder during retraction of the brakes to compensate for brake shoe wear.

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 master cylinder includes a housing (22) with a bore (24) for receiving a pair of pistons (36, 38). The housing defines a reservoir (28) with an outer wall (26). The housing also defines at least one outlet passage (62, 66) communicating fluid from the bore (24) to a brake assembly (16). The outlet passage (62, 66) is partially defined by a boss (60) formed integrally with the housing (22) and the boss (60) cooperates substantially with the outer wall (26) to separate the reservoir (28) into a pair of cavities (84, 86).

Abstract: A differential master cylinder adapted for use as fluid pressure generating source in a brake system comprises a cylinder body having a stepped cylinder formed therein; a stepped piston arranged to be slidable within the stepped cylinder; a first chamber defined by the end of a portion of smaller diameter of the stepped piston and a portion of smaller diameter of the stepped cylinder; a second chamber defined by the stepped piston and a portion of larger diameter of the stepped cylinder; a first fluid passage provided at the stepped piston and arranged to have the first and second chambers intercommunicate; a check valve arranged in the first fluid passage to close when fluid pressure within the second chamber reaches a first setting value; and a relief valve arranged to open to return the fluid from the second chamber to a reservoir when the fluid pressure within the second chamber reaches a second setting value which is higher than the first value.

Abstract: A short master cylinder assembly having a transversely disposed compensation and bypass port controlled by a check valve. The check valve is cammed to the open position by a pressurizing piston, and is closed by spring action upon movement of the pressurizing piston in the pressure actuating direction.

Abstract: A master cylinder includes a housing defining a reservoir and a bore for movably receiving a pair of pistons. A primary piston cooperates with a secondary piston to define a primary chamber therebetween and cooperates with the housing to substantially define an auxiliary chamber. The primary chamber and auxiliary chamber are disposed within a substantially uniform diameter section of the housing bore. The primary piston is movable within the bore to communicate fluid pressure from the auxiliary chamber to the primary chamber until a predetermined pressure level is reached in the primary chamber whereupon the auxiliary chamber is vented to the reservoir. A sealing member disposed within a recess on the bore cooperates with the piston to define the auxiliary chamber. Upon initial movement of the piston relative to the sealing member, a small portion of the fluid within the auxiliary chamber is communicated to the reservoir so as to bleed the auxiliary chamber.

Abstract: A master cylinder for a hydraulic brake system includes a piston which divides a primary bore into a primary chamber and a secondary chamber. The piston rod sealingly slides in a secondary bore of smaller cross-sectional area than the primary bore. An expander piston sealingly slides in a bore and defines a primary expander chamber and a secondary expander chamber. In use, initial movement of the piston causes fluid to be displaced from the primary chamber to the brake circuit at a rate corresponding to the area of the primary bore. When the pressure in primary chamber becomes sufficiently large the expander piston is moved to the right against the bias of a spring to allow fluid to flow out of primary chamber into primary expander chamber via a passage. An equal volume of fluid is displaced from secondary expander chamber into secondary chamber via a passage.

Abstract: A master cylinder (10) includes a housing (24) defining a bore (26) therein and a fluid reservoir (38) communicating with the bore via a passage (30). A stepped piston (94) is reciprocably received in the bore and cooperates with the housing to define a pair of variable-volume pressure chambers (108, 110). An annular valve apparatus (106) circumscribes the stepped piston within the housing bore and sealingly cooperates with the stepped piston and housing to bound the pair of variable-volume pressure chambers. The valve apparatus is pressure responsive to control fluid communication between the pair of pressure chambers and through the passage.

Abstract: A dual master cylinder (10) includes a pair of pistons (62, 106) moving in a bore (14) to contract a pair of pressure chambers (64, 108). A housing 12 defines a pair of inlets (26, 28) communicating liquid from a reservoir (18) into the pair of pressure chambers (64, 108). A pair of outlets (46, 48) communicate liquid from the pair of pressure chambers (64, 108) to a pair of brake systems (50, 52). A pair of tilt valves (34, 36) control liquid communication through the inlets (26, 28). The pair of pistons (62, 106) carry a pair of valve actuators (182, 210) which open and close the pair of tilt valves (34, 36) in response to movement of the pair of pistons (62, 106) within the housing (12). The pair of actuators (182, 210) cooperate with one another to simultaneously close the pair of tilt valves (34, 36) during a brake application.

Abstract: A two step pressure intensifier adapted for use as a clamp or a via including a housing cylinder which sealingly houses a telescoping cylinder. The telescoping cylinder is extended rapidly outward by application of low pressure to hydraulic fluid within the telescoping cylinder. Upon meeting resistance, the extension speed of the telescoping cylinder is slowed down and high presssure is applied.The use of a small diameter force input rod or piston is encompassed by a close fitting input portion of the telescoping piston so that the two pistons move together during a portion of both their force and retraction strokes.

Abstract: A brake master cylinder device includes a first and a second cylinder bore formed within a body. A piston member is formed with a first piston and a second piston, which are respectively engaged with the first and the second cylinder bores to define a first and a second cylinder chamber, the arrangement being such that when the piston member is moved in a certain direction the volumes of both the first and the second cylinder chambers are reduced together. The piston member is biased in the direction opposite to said certain direction. A fluid conduit opens from the second cylinder chamber for connection to a brake actuator. A means for transferring fluid allows brake fluid to pass substantially freely from the first cylinder chamber to the second cylinder chamber. A fluid accumulator is communicated with the first cylinder chamber, and commences to accumulate fluid from it when the pressure in it rises to a predetermined pressure value.

Abstract: The present invention relates to a brake master cylinder device including a first and a second cylinder bore formed within a body. A piston member is formed with a first piston and a second piston, which are respectively engaged with the first and the second cylinder bores to define a first and a second cylinder chamber, the arrangement being such that when the piston member is moved in a certain direction the volumes of both the first and the second cylinder chambers are reduced together. The piston member is biased in the direction opposite to said certain direction. A fluid conduit opens from the second cylinder chamber for connection to a brake actuator. A first one way valve always allows fluid to flow freely from the first to the second cylinder chamber. A second one way valve allows fluid to flow from a fluid reservoir, within which fluid is kept at atmospheric pressure, to the first cylinder chamber, when the pressure in the first cylinder chamber is below atmospheric pressure.

Abstract: A master cylinder apparatus of a type of wherein a master cylinder which is in communication through a connecting port with an oil reservoir on its upper side. A piston is provided having at its front and rear surfaces respective elastic cups, whereby the piston may be pushed to advance against the action of a spring on its front side by a push rod. The piston comprises a front main piston and a rear subsidiary piston connected thereto, and is further defined by an axially extending return port communicating between front and rear oil chambers and with a check valve interposed in the return port arranged to be closed by the action of a releasable spring supported by a stopper at the rear surface, during advance motion of the piston.

Abstract: In a master cylinder a housing defines a bore for movably receiving a pair of pistons. A pair of seals cooperate with the pair of pistons to define a pair of pressure chambers and a sleeve disposed within the bore fixedly locates the pair of seals within the bore so that when the pair of pistons are moved within the bore, the pair of pistons move relative to the pair of seals to displace fluid within the pressure chambers to respective brake circuits. A bearing member engages the sleeve to fixedly retain the sleeve within the bore and cooperates with one of the pair of pistons to define an auxiliary chamber which is contracted during a brake application to communicate fluid to one of the pair of pressure chambers.

Abstract: In a mixed medium brake system for a motor vehicle, there is provided a hydro-pneumatic brake cylinder device in a common housing having a compact configuration that is realized by designing the hydraulic piston in the form of a cylindrical plunger having a hollow cavity in the end adjacent the pneumatic piston, whereby engagement of the pneumatic piston push rod with the plunger is at a location thereof forward of the end adjacent the pneumatic piston, thus minimizing the distance required between the pneumatic piston and the hydraulic piston formed by the plunger. Such an arrangement also reduces the binding action of the cylindrical plunger in its guide bore for improved operation, while accommodating pivotal motion of said pneumatic piston.

Abstract: An hydraulic booster in which a control chamber is defined between an input piston and a second piston relative to which the input piston is movable, and recuperation valve for controlling communication between the control chamber and a reservoir is located in the control chamber. The recuperation valve closes upon relative movement of the input piston towards the second piston, further movement of the input piston in the same direction causing pressurization of fluid trapped in the control chamber.

Abstract: A master cylinder provides a housing defining a reservoir and movably carrying a pair of pistons within a bore in communication with the reservoir. The pair of pistons cooperate with the housing to substantially define a pair of pressure chambers which communicate with respective brake circuits. One of the pistons forms a cavity to receive a reaction piston and the one piston also carries a proportioning valve. The reaction piston forms an auxiliary chamber within the one piston and the proportioning valve is exposed to the auxiliary chamber. The reaction piston extends outwardly into one of the pressure chambers to engage the housing and the valve member is responsive to the fluid pressure in the other pressure chamber to control fluid communication between the auxiliary chamber and the reservoir.

Abstract: A master cylinder assembly includes a body in which fluid pressure is developed. A fluid reservoir is detachably attached to the sides of the body. Fluid communication between the fluid reservoir and the body is provided through one of the sides of the body.

Abstract: A two step pressure intensifier system consisting of three piston-cylinder units in coaxial arrangement, the first unit being a low pressure medium supplied to it to jointly move the pistons of all the units. The initial movement employing the second unit for a moderate pressure increase and the final movement bringing the piston of the third unit into its cylinder for a high pressure increase.

Abstract: The invention relates to master cylinder and actuator assemblies in which a push rod connected to the actuator extends forwardly through a vehicle mounting member and is engageable at its forward end with a piston, there normally being a clearance between the push rod and the piston in their inoperative positions. Such assemblies suffer from the disadvantage that a desired working clearance is difficult to attain due to manufacturing tolerances. Embodiments of the present invention overcome that disadvantage and provide an assembly which includes a lateral projection (10) on the push rod (5), which projection limits rearward movement of the push rod relative to the mounting member (3).

Abstract: A hydraulic reservoir and master cylinder assembly having a piston with a blind bore for receiving an input rod, the piston having a breather valve therein provided with opening means operated by an abutment projecting laterally into the master cylinder bore and which is received into a slot in the piston. In order that the abutment be as short as possible and therefore that the slot be as shallow as possible, the piston carries a pivoted lever extending transversely of the piston and which is engageable with the abutment to operate the breather valve.

Abstract: A hydraulically operated disk brake apparatus for a motor vehicle comprises a brake disk, a caliper-like brake housing disposed to straddle over the brake disk and having a pair of arms, and a pair of brake pad assemblies disposed in the brake housing in opposition to each other with the brake disk being interposed therebetween. The brake pad assemblies are movable toward and from the brake disk. A cylinder chamber is formed in one of the caliper arms and accommodates therein a first piston for pressing the adjacent brake pad assembly to the brake disk and a second piston positioned with a distance from the first piston. The second piston is operated by an externally provided actuator member to produce a hydraulic pressure in the cylinder chamber for moving the first piston and the associated brake pad assembly toward the brake disk. A reservoir for hydraulic fluid is formed in the brake housing to supply supplementary fluid into the cylinder chamber.

Abstract: A master cylinder has a housing with a bore therein having a tapered section located between first and second compensator ports connecting the bore to a reservoir. A sleeve locates first and second lip seals adjacent the first and second compensator ports, respectively. A first piston engages the first lip seal and a second piston engages the second lip seal to define first and second chambers within the bore. A bearing member which surrounds the first piston engages the sleeve and holds the first and second lip seals in a stationary position within the bore. Thereafter, an input member moves the first and second pistons past the first and second lip seals to pressurize the fluid in the first and second chambers and provides fluid pressure responsive devices with an operational input through first and second outlet ports in the housing.

Abstract: A master cylinder including a housing having a fluid reservoir and a cavity. A first piston is movable in the cavity. A sealing member is positioned for movement with the first piston. A fluid chamber is formed in the cavity ahead of the first piston. A second piston is movable within the first piston into and out of sealing engagement with the sealing member to close and open, respectively, a fluid path between the fluid reservoir and the fluid chamber.

Abstract: In a master cylinder assembly of the kind in which transfer chambers in pedal-operated master cylinders are connected by a transfer passage, each master cylinder has a transfer valve which is normally open and which is movable into a closed position to isolate the transfer chamber of that master cylinder from a reservoir in response to an increase in pressure in the transfer chamber when the other master cylinder is operated on its own.

Abstract: A master cylinder for a vehicle braking system. The master cylinder including a housing defining a bore therewithin with a piston slidably mounted in said bore. The piston head and the housing bore define a pressure chamber in communication with at least one brake actuator. A conventional annular ring cooperates with the wall of the housing bore and with a radial surface of the piston head for controlling fluid communication between a supply chamber of the master cylinder which communicates with a reservoir and the pressure chamber. The annular ring has a lip which projects toward the radial surface so as to form a non-return valve which prevents fluid communication from the pressure chamber toward the supply chamber when the master-cylinder piston is out of its rest position.

Abstract: A tandem master cylinder comprises two pistons, one of which includes a cylindrical bore for receiving therein the other piston, and limiting means for limiting the axial movement of the other piston.

Abstract: A control member responsive to a predetermined operational pressure signal for transferring that portion of an input force acting on a first diameter of a pressurizing piston in a two stage servomotor to a second diameter. The input force acts on the pressurizing piston and moves the second diameter section thereof in an outlet chamber to further pressurize the fluid therein and meet an operational demand associated with the input force.

Abstract: A brake master cylinder contains a primary and a secondary piston each having an associated brake fluid reservoir and compensator valve. Normally, the primary piston is actuated directly by mechanical force and the secondary piston is actuated by fluid pressure acting on it from the primary cylinder. If brake fluid pressure fails in either primary or secondary piston regions, the unfailed piston thereupon responds directly to mechanical actuating forces to produce normal brake fluid pressure in its associated wheel cylinders without interference from the failed piston.Compensator valves, external to the cylinders enable brake fluid replenishment without requiring additional cylinder length.

Abstract: A master cylinder assembly has a low pressure, high volume displacement quick take-up chamber and a high pressure, low volume displacement pressurizing chamber formed by a stepped bore and a stepped piston. A compensation control and blow-off valve unit has a peripheral lip seal type valve providing compensation flow on break release but preventing flow from the quick take-up chamber during brake apply. A normally closed check valve is held open while the master cylinder is in the fully released position to provide communication between both pressurizing chambers and the fluid reservoir. As the pressurizing cup for the high pressure chamber closes its compensation port, the check valve is permitted to close by camming action of a valve pin and a camming surface on the piston. Initial flow is obtained from the quick take-up chamber past the pressurizing cup into the high pressure chamber.

Abstract: A master cylinder assembly for simultaneously actuating the front and rear wheel brakes of a vehicle. The master cylinder assembly includes a housing having a bore therein with a first piston separated from a second piston by a first spring to establish a first pressurizing chamber while a second spring separates the second piston from the bottom of the bore to establish a second pressurizing chamber. The first and second piston each have a compensating passage therethrough for communicating fluid from a reservoir into the first and second pressurizing chamber, respectively. A first valve seat located in the first pressurizing chamber is connected to a second valve seat in the second pressurizing chamber. A valve return spring in the second pressurizing chamber urges the first and second valve seats toward the first and second pistons.

Abstract: A master cylinder has a housing with a bore therein having a tapered section located between first and second compensator ports connecting the bore to a reservoir. A sleeve locates first and second lip seals adjacent the first and second compensator ports, respectively. A first piston engages the first lip seal and a second piston engages the second lip seal to define first and second chambers within the bore. A bearing member which surrounds the first piston engages the sleeve and holds the first and second lip seals in a stationary position within the bore. Thereafter, an input member moves the first and second pistons past the first and second lip seals to pressurize the fluid in the first and second chambers and provides fluid pressure responsive devices with an operational input through first and second outlet ports in the housing.