Abstract: A guard means for protecting a valve body extending from a hub of a servomotor. The valve body has a base with a plurality of openings therein through which mounting bolts attach the guard means to the housing of the servomotor, a bellows section having a first diameter extending from the base and connected to a second diameter by a taper, and an end member connected to the second diameter of the bellows section. The bellows section has a plurality of pleats, a portion of which are selectively locked in either a compressed position or an extended position to locate the end member adjacent the end of the valve body when the valve body is in its fully extended position. The pleats in the first diameter of the bellows section have a different closure force than the second diameter to selectively establish which of the first and second diameters of the bellows section that will initially move to locate said end section adjacent the end of the cylindrical member.

Abstract: A spring and lever arrangement for imparting a spring force to a plunger of a control valve in a brake booster. The spring force is combined with an input force applied to the plunger during a brake application. A reaction force created by the resistance to movement of a pressurizing member by a output force developed in response to the input force overcomes the spring force and input force to control the development of an operational pressure differential such that the resultant output force for effecting a brake application varies as a nonlinear function.

Abstract: A method of establishing a spring force for a push rod of a control valve in a brake booster to set the force which opposes an operational input force. After attaching the push rod to a plunger, the plunger is located in the bore of a hub of a movable wall of the brake booster. When the plunger is installed in the bore, a groove located adjacent a threaded end of the push rod extends past the hub. A spring and sleeve are placed on the push rod and a fixture attached to the rear shell of the booster. The push rod and sleeve pass through an opening in the fixture to align the push rod within the axial center of the bore of the hub. A force is applied to the push rod to move the push rod within said bore to establish a rest position of the plunger with respect to a seat on a poppet valve. Thereafter, a force is applied to the sleeve to initially move the sleeve on said push rod to bring the spring into engagement with the hub and thereafter compress the spring until a predetermined spring force is established.

Abstract: A brake booster is disclosed. More specifically, an improvement relating to a reinforcing plate which is used to reinforce a shell to which a master cylinder is connected is disclosed. The reinforcing plate comprises a pair of members, i.e. a first reinforcing plate which is disposed along the inner surface of the shell which provides a mounting surface for a master cylinder, and a second reinforcing plate which is disposed along the inner surface of the shell at a location radially outward of the mounting surface for the master cylinder. The rigidity of the shell can be increased without increasing a sheet thickness thereof.

Abstract: A pneumatic brake booster of the tandem type for the brake boosting of motor vehicles, comprises a movable hub (15) driving a push rod (11) by of a reaction disk (17), a closed containment composed of a front shell (1) on the same side as the master cylinder and of a rear shell (3) on the same side as the actuating pedal, which define a front chamber and a rear chamber separated by a separating element (5) having an annular partition (9), and a front piston (25) and a rear piston (35) respectively arranged coaxially in the front and rear chambers. These chambers are themselves respectively divided by a sealing diaphragm (27, 37) fixed to each of the pistons (25, 35), in order to define, within each of these, a sub-chamber of constant pressure (21, 31) and a sub-chamber of variable pressure (23, 33), the pistons (25, 35) being movable in the axial direction under the effect of the differences in the pressures prevailing between the sub-chambers of each chamber.

Abstract: A hydraulic booster for a vehicle brake master cylinder having a power piston with only one large diameter sliding seal which is exposed to a high hydraulic pressure. This provides a brake booster having lower hysteresis.

Abstract: A reaction transmitting mechanism for brake booster in which a reaction from an output shaft is transmitted to an input shaft through a reaction disc, a reaction transmitting member and a valve plunger. An annular member is fitted over the valve body, and is formed with a stepped opening, in which a stepped tubular reaction transmitting member is slidably fitted. The reaction transmitting member is formed with a through-opening, in which the front end of the valve plunger is slidably fitted. The right end face of the flange-like portion of the reaction transmitting member is disposed in opposing relationship with the valve body and the step in the valve plunger. As a result of such arrangement, a more free choice of servo ratios used upon actuating and releasing the brake is allowed as compared with the choice enabled in the prior art.

Abstract: An adjustment member having an end cap with threads thereon that match threads on the hub of a movable wall in a vacuum brake booster. The end cap has a plurality of projections located on its peripheral which allow a tool to rotate the end cap with respect to the hub and establish a space relationship between the hub and plunger to define a gap between said plunger and resilient member. The gap delaying the engagement of the resilient member and plunger until after a predetermined output force develops across the wall. The end cap has a central opening through which the reaction disc is thereafter communicated to oppose movement of the plunger by an operator input force during a brake application.

Abstract: Apparatus for preventing percussion beats in a brake booster is disclosed. The apparatus prevents percussion beats from occurring as a result of an abutment of a valve plunger, which forms part of a valve mechanism, against a key member which is used to prevent the valve plunger from being withdrawn from the valve body. An elastic member is formed on at least one of the key member and the valve plunger. The key member and the valve plunger are formed with abutting surfaces thereon which are adapted to abut against each other. A normal spacing between the abutting surfaces is chosen to be greater than a spacing as measured between the elastic member and the other member which is abutted by the elastic member. In this manner, the occurrence of percussion beats as the key member abuts against the valve plunger is prevented while also preventing a reduction in the durability of the elastic member.

Abstract: An improvement of a variable pressure passage formed in the valve body of a brake booster is disclosed. A variable pressure passage including a first radial passage in which a key member is inserted and a second radial passage continuing from and located rearward of the first radial passage is the basis of the invention. According to the invention, a third radial passage, which also forms the variable pressure passage, is located forwardly of and continues from the first radial passage, and has a circumferential width less than that of the key member. This allows a corresponding increase in the channel area of the variable pressure passage, thereby improving the operational response of the brake booster without the need to increase the axial size of the valve body since the third passage is formed forwardly of the key member.

Abstract: A brake booster (12) and check valve (36) wherein the housing (38) of the check valve (36) has a plurality of legs (52, 52'. . . 52.sup.N) with a disc (56) located thereon. The legs (52, 52'. . . 52.sup.N) which extend through slots (55, 55'. . . 55.sup.N) in the shell (30) of the brake booster (12) have tabs (54, 54'. . . 54.sup.N) that lock the housing (38) to the shell (30). The disc (56) has an annular rib (58) which engages the shell (30) to form a seal to prevent air from entering chambers (24, 40). The housing (38) is connected to a source of vacuum and a flapper (60) positioned over a plurality of openings (32, 32'. . . 32.sup.N) in the shell (30) to allow vacuum in the chamber (40) to evacuate air from the brake booster (12).

Abstract: A pneumatic booster for use, for example, in a brake system of a vehicle, and designed so that the overall axial length is reduced without interfering with the operation thereof. The booster comprises a valve body which is movable back and forth between first and second positions in a housing that is divided by a diaphragm with a power piston into front and rear chambers communicated with respective pressure sources, a valve which allows at least one of the front and rear chambers to selectively communicate with the pressure sources which differ from each other in the level of pressure, and a guide which slidably fits on the outer periphery of the valve body. The valve body has a passage one end of which opens on the outer periphery thereof to connect one of the front and rear chambers to the associated pressure source, the opening of the passage being positioned in the axial direction of the valve body so that the guide overlaps the opening when the valve body is at either the first or second position.

Abstract: An improvement of a variable pressure passage which is formed in a valve body of a booster, for example, a brake booster, is disclosed. The valve body which is disposed within a shell of the booster comprises a first and a second tubular member which are connected together. An axial space is defined by the outer peripheral surface of the first tubular member and the inner peripheral surface of the second tubular member when they are integrally connected together, and forms a variable pressure passage providing a communication between forwardly and rearwardly located, variable pressure chambers. This avoids the formation of an axial bore and a radial opening which are formed in a solid portion of a single member valve body, as occurs in the prior art, thus allowing the mechanical strength of the valve body to be improved.

Abstract: A brake booster includes a housing in which a constant-pressure chamber and a variable-pressure chamber are defined by a power piston. An input rod is operatively connected to one end of the power piston and receives an input force. A valve is provided in the power piston and operatively connected to the input piston so as to open upon receipt of the input force in such a manner that the differential pressure between the chambers moves the power piston. An output rod is operatively connected to the other end of the power piston. A wall member is provided across which a first auxiliary chamber at a side of the variable-pressure chamber and a second auxiliary chamber formed at a slide of the constant pressure are formed. An orifice passage connects the variable pressure chamber and the first auxiliary chamber.

Abstract: In order to eliminate the noises caused on operation of a vacuum brake power booster, a radially outwardly extending air-conducting surface (26), which tapers toward a poppet valve member (7) closing a sealing seat (19) and which is opposite to the channel (25) on actuation, is adjacent to the radially outwardly disposed area of the sealing seat (19) designed on a valve piston (10), the sealing seat being released on displacement of the valve piston (10) and permitting inflow of the atmospheric air into the working chamber (3) of the booster via a radially extending channel (25).

Abstract: A brake valve for a vacuum brake force booster, wherein the valve body (33) is movably located on the pedal piston (32). The valve body, through two springs (35, 39) is held in a central position in which the brake pedal and pedal piston may move the valve body between booster deactivated and deactivated positions. Two electromagnets (37, 40) are provided which draw the valve body (33) both in the actuating direction and against the actuating direction. In this manner, the valve (17) can be actuated independently of the pedal force, to either release or apply braking pressure as for automatic antislip or traction control.

Abstract: In the negative pressure booster equipment according to the present invention, a valve plunger 17 and an input shaft 18 are incorporated in a single member. Also, the axial length of the guide 17a of the valve plunger in relation to the valve body 4 is set to such size as to allow the angle of the maximum inclination of the input shaft 18 during operation. Further, a retainer 27 to support a spring 33 of a control valve 22 is removably mounted on the input shaft 18 from the atmospheric air inlet of the valve body 4. Accordingly, in the case of valve disc 24 is to be replaced, valve disc 24 and other rubber products can be readily replaced by removing the retainer 27 without disassembling the valve plunger 17 or the input shaft 18 from the valve body 4. Because the valve plunger 17 and the input shaft 18 are incorporated, the caulking process for the members 17 and 18 are not required.

Abstract: A vacuum brake power booster, in particular for motor vehicles, which includes a poppet valve (12) sealing two valve seats (18, 19) and which is axially deformable within the area of a rolling fold (15) also includes an annular part which is either mounted on the outside of the rolling fold (15) in a form-fit manner or arranged inside the elastic material (24) of the poppet valve (12). This annular part prevents the rolling fold (15) from being blown up outwardly due to the pressure differential prevailing between its two sides so that it will be possible to reduce the return force and thus also the response force.

Abstract: A hydraulic booster for slip-controlled brake systems, including a booster piston (1) arranged in a booster housing (11) and confining a booster chamber (4). A braking pressure control valve is provided whose control part (12) is actuatable by a lever mechanism (13) as a function of the piston of the control part (12). An actuating piston (2) is displaceably guided in the booster piston (1) and is positioned by way of a push rod which cooperates with the lever mechanism (13). To provide a hydraulic booster to realize boosting factors of any desired size, both of constructional and strength-minimizing nature, an annular surface (24) is formed the stepped actuating piston (2), on the side of the push rod (22) and is larger than the total area of any opposing annular surfaces, subject to the booster chamber pressure to create a net force acting to oppose the push rod force and allow setting of the boosting factor by adjustment of the area of the annular surface.

Abstract: A pneumatic booster includes a casing, a valve body axially movably disposed in the casing and having a tubular portion extending backward to the outside of the casing and open at the rear end thereof, a set of a power piston and a diaphragm fixedly mounted on the valve body and partitioning the interior of the casing into a constant pressure chamber communicating with a negative pressure source and a variable pressure chamber adapted to selectively communicate with the negative source and the ambient air, a valve unit disposed in the tubular portion of the valve body for selectively placing the variable pressure chamber in communication with the negative pressure source and the ambient air, an input rod extending into the tubular portion of the valve body for actuating the valve unit, and an output rod connected to the valve body.

Abstract: A peripheral sealed interlock for a dual diaphragm tandem vacuum booster with front and rear housings is provided. An outer radial peripheral end of a divider of the inventive interlock is greatly simplified and in the preferred embodiment a bead of a secondary diaphragm is allowed to seal on a rear housing member as well as with the periphery of the divider. The interlock provides a simplified design allowing independent compression of primary and secondary diaphragm beads while at the same time providing an interlock which require lower compression for assembly and sealing.

Abstract: A seal unit for a brake booster such as of a tendem type including a centerplate disposed within a shell is disclosed. Annular seal means maintains a hermetic seal between the centerplate and a valve body. According to the invention, the annular seal means is formed with a passage which provides a communication between the inner and the outer periphery thereof. This allows a communication between the inner and the outer periphery of the annular seal means to be maintained by the passage formed therein in the event the opening of a constant pressure passage (or variable pressure passage) formed in the valve body is closed by the annular seal means. This allows a spacing between the annular seal means and a power piston or pistons mounted on the valve body to be reduced, contributing to reducing the overall length of the brake booster.

Abstract: A liquid pressure booster which may be used in a brake booster or the like is disclosed. A second supply passage is provided which allows a power chamber of the liquid pressure booster to communicate with an external source of pressure fluid without passing through a valve mechanism of the liquid pressure booster. A first open/close valve is operative to open or close the second supply passage, and a second open/close valve is effective to open or close a discharge passage of the liquid pressure booster. A controller controls the first and the second open/close valve. With this construction, the controller may be caused to open the first valve and to close the second valve to allow the pressure fluid to be introduced into the power chamber through the second supply passage without depressing a brake pedal to cause a forward movement of an input shaft. In this manner, the liquid pressure booster can be operated automatically, and thus such booster can be advantageously used in an automatic braking unit.

Abstract: The pneumatic brake booster comprises a housing formed from a front and a rear half-shell 12 and 10, a piston structure dividing the housing internally into two chambers and composed of an assembly consisting of a plate 18 and of a diaphragm 20 and possessing centrally a hub structure 24 containing a distribution valve mechanism 26 actuatable by an input member 56 in order to generate a pressure difference selectively between the chambers. The valve mechanism 26 comprises a plunger 28 mounted axially slideably in a coaxial central bore 30 of the valve body and connected to the input member 56, the plunger defining a first shutter seat 32 at one of its ends, a second shutter seat 34 being formed in the valve body concentrically relative to the first shutter seat and a shutter means 36 mounted in the valve body and stressed elastically toward the first and second shutter seats, at least one elastic means 60 stressing the input member 56 axially away from the shutter seats.

Abstract: A brake booster-mounting construction includes a reinforcement plate which is adapted to be fastened, jointly with a shell, to a fixing member by stud bolts extending outwardly from a shell wall. The brake booster-mounting construction is characterized in that; in its non-mounted condition, the reinforcement plate is abutted against an outer peripheral portion of said shell, and also that portion of the reinforcement plate to be jointly fastened by the stud bolts is spaced from the shell; and in its mounted condition, the reinforcement plate spring-urges a brake booster in a direction away from the fixing member.

Abstract: An improvement relating to a front shell of a brake booster and a reinforcing plate which is connected to and extends along the inner surface of the front shell is disclosed. A radially inward portion of the front shell is formed with a cylindrical section which extends rearwardly, and an end face which provides a mounting surface for a master cylinder is defined adjacent to the rear end of the cylindrical section. The reinforcing plate is formed with a cylindrical portion which is fitted around the cylindrical section of the front shell, and an end face which is disposed in overlapping relationship with the end face of the front shell. This allows the rigidity of the front shell to be increased without requiring the welding of the reinforcing plate to the front shell.

Abstract: A seal unit is provided for a brake booster such as of a tandem type which includes a center plate within its shell. The brake booster includes annular means disposed within the shell for maintaining a hermetic seal between the center plate and a valve body. An axial portion of the center plate is formed with an axially extending cylindrical portion, the end of which is folded radially inward to define a U-shaped fold. The annular seal means is fitted inside the cylindrical portion, with its part disposed between the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the fold. This effectively prevents the annular seal means from being withdrawn from the center plate.

Abstract: A tandem type brake booster is disclosed which comprises a booster body, a partitioning wall partitioning the interior of the body into front and rear chambers, a valve body axially movably disposed in the body, front and rear power pistons provided with respective diaphragms associated therwith and respectively dividing the interior of the front and rear chambers into respective constant and variable pressure chambers, a plunger axially movably disposed in the valve body, and a valve mechanism disposed in the valve body to selectively introduce atmospheric air and negative pressure into the variable pressure chambers. The valve body includes a large diameter portion on which the front and rear power pistons are secured and a small diameter portion, the large diameter portion being provided adjacent to the rear end thereof with a slightly reduced diameter stepped portion, the small diameter portion being provided with a circumferentially extending groove.

Abstract: The vacuum servomotor comprises a main casing (12) divided sealingly on the inside into first and second chambers (10, 20) by a flexible membrane (9) bearing on a rigid disk (7) integral with an activating piston (3). The first chamber (10) is subjected to a low pressure, while the second chamber (20) is subjected either to this low pressure or to a higher pressure. An auxiliary casing (25) is integral with the rigid disk (7) and projects into the first chamber (10), an auxiliary piston (27) sealingly dividing the auxiliarly casing (25) on the inside into third and fourth chambers (30, 40), the third chamber (30) being closed by the rigid disk (7), the auxiliary piston (27) being mounted stationary relative to the main casing (12).

Abstract: In order to reduce the number of component parts required for the simultaneous ventilation of two power chambers of a tandem brake power booster and to avoid sealing problems. A booster, according to the invention, provides for the transmission of the boosting power of the master cylinder-side movable wall of the booster to be directly to the control housing.

Abstract: The hydraulic brake booster (12) of the present invention comprises a full power hydraulic brake booster (12) that provides false travel during full power operation and improved pedal feel during manual operation. The booster (10) has a housing (24) with a slidable sleeve assembly (60) therein, the assembly (60) housing a sleeve member (98) which is displaced by accumulator fluid pressure against a collet housing (78) and a moveable collet member (79) located about an input member (94). The sleeve member (98) displaces the moveable collet member (79) against a resilient member (77) when the sleeve member (98) is displaced by hydraulic fluid pressure from the accumulator (14).

Abstract: A boot (19) protecting the pedal-sided end (18) of the control valve housing (5) of a vacuum brake force booster is fixed by a spacer. The spacer is preferably configured as a dual-walled annular sleeve (20). It is axially secured in the same position as a ring sealing the control valve housing (5) against the booster housing (1). An axial extension (26) of sleeve (20) insures that the boot (19) is kept remote from the booster housing (1) and from the control valve housing (5), respectively, so that air can be taken in between boot (19) and control valve housing (5) for ventilating the working chamber (3). This design allows the air required for ventilation to travel very closely to the baffle wall, thereby minimizing noise in the passenger cabin of the automobile.

Abstract: The invention provides a brake booster including in a preferred embodiment a housing, first and second annular flexible diaphragms spaced from one another forming a sealed second chamber within the housing and a sealed first chamber between the first diaphragm and the first end of the housing, a generally annular shaped power piston for connection with the master cylinder piston, a chamber valve seat separating the first and second chambers, an inlet valve slidably mounted within the power piston, and a control valve spring biased away from the power piston and connected with the pedal linkage and being slidably and sealably mounted within first end of the housing.

Abstract: A pneumatic booster comprising a housing, a power piston separating the inside of the housing into a constant pressure chamber and a variable pressure chamber, a valve body attached to the power piston, an output shaft, a plunger slidably received in a bore in the valve body, an input shaft and a valve mechanism in the bore for selectively communicating the variable pressure chamber with a negative pressure source or the atmospheric pressure, the valve mechanism including a valve member mounted on the inner wall of the bore, a first valve seat formed on the inner wall of the bore and a second valve seat formed on the plunger.

Abstract: A valve mechanism for a brake booster includes a valve element and a valve seat, either of which includes a first seat through which an orifice passage is formed and a second seat. Under an intermediate load condition when a forward movement of an input shaft ceases, the first seats become engaged with each other and the orifice passage is effective to maintain a communication therethrough. Subsequently when the valve element and the valve seat are more strongly abutting together, the second seats engage to interrupt the communication.

Abstract: A brake booster such as a tandem brake booster including a center plate disposed within a shell is disclosed. The center plate is connected to a valve body disposed within the shell by seal means in the form of a diaphragm, thus allowing the entire length of the valve body and hence of the brake booster to be reduced as compared with the prior art arrangement.

Abstract: To substantially eliminate the noise arising upon actuation of a vacuum brake force booster caused by incoming air, the housing section confining the ventable working chamber and/or the intervals in the control valve housing are lined with an insulating composition for attenuating noise.

Abstract: The process is for adjusting the value of the jump of a brake booster, in which are movably mounted a hollow boosting piston, a control rod carrying a plunger seated in the piston and a push rod, boosting means being controlled as a result of a forward movement of the plunger and their effect being to move the piston forwards, a reaction disc being interposed between an annular front face of the piston and a rear face of the push rod, the booster being intended for actuating a master cylinder.

Abstract: The invention relates to a brake booster of the type for motor vehicles comprising a casing and a diaphragm which divides the interior of the casing (5) sealingly into a front chamber and a rear chamber, a hollow piston (10) movable in the casing, an input member (14, 16) intended to be connected to a brake pedal (18), an output assembly (20, 26) intended to be connected to a piston of a master cylinder, and a reaction disk (32) made of a deformable material and arranged between the hollow piston (10) and the output assembly (20, 26), in order to receive the output force of the booster when it is put into operation, the output force causing a first deformation of the reaction disk (32), this deformation tending to push back the input member (14, 16). According to the invention, the output assembly (20, 26) is formed in two parts, one movable relative to the other counter to a spring means (36), in order to act on a reduced surface of the reaction disk ( 32).

Abstract: In order to enable a brake booster to operate both with a pressure above atmospheric and with atmospheric pressure without any negative mutual influences of the two energy types and without any change in the responding behavior of the device in case of failure of either energy type, the invention provides a pneumatic system which, during the operation of the brake booster with pressure above atmospheric, causes a force constituent to become active so as to counteract the forces caused by the increased pressure difference and acting on the control valve piston as well as on the control valve housing.

Abstract: An open/close valve which opens or closes a passage providing a communication between a valve mechanism and a constant pressure chamber of a brake booster is disclosed. The valve comprises a valve seat formed in surrounding relationship with a passage, a valve element disposed within a casing which is mounted on the valve body so as to be reciprocably movable therein, and a pressure chamber defined within the casing for urging the valve element toward the valve seat. Pressure fluid supply means supplies a pressure fluid into the pressure chamber from the outside of a shell to cause the valve element to be seated upon the valve seat. As compared with the solenoid-operated valve, an axial size of the open/close valve can be reduced while avoiding any heating effect.

Abstract: In the negative pressure booster equipment 1 according to the present invention, a groove 27 is provided on the inner peripheral beads 14a and 16a of the diaphragms 14 and 16, fixed on the valve body 8 and forming the power pistons in order to communicate the variable pressure chambers 5b and 7b divided by the diaphragms 14 and 16 with the passages 26 and 28 corresponding to the variable pressure chambers 5b and 7b. Accordingly, the air passages are opened to the variable pressure chambers 5b and 7b through the groove 27 formed on the beads 14a and 16a of the diaphragms 14 and 16. According to this invention, therefore, there is no need to provide wide gap between the fixed portion of the beads and the center plate in order to open the air passages to the variable pressure chambers. This makes it possible to shorten overall length of the negative pressure booster equipment 1.

Abstract: The negative pressure booster equipment according to the present invention is provided with a variable orifice, by which the area of the air passage in the pathways other than one pathway, of two or more pathways communicating two or more variable pressure chambers with atmospheric air, is gradually decreased as the valve plunger moves forward, and it is gradually increased as the valve plunger moves backward in relation to the valve body. Consequently, the pathways other than one pathway are throttled by the variable orifice as the valve plunger moves forward. As the result, most of the air flowing through the control valve is intensively introduced into the variable pressure chamber communicating with the pathway, which is not throttled by the variable orifice, and the pressure in this variable pressure chamber is rapidly increased.

Abstract: A brake booster of triple type comprises a shell in which constant pressure and variable pressure chambers are formed. According to the invention, individual variable pressure chambers defined within the shell communicate with a valve mechanism through respective variable pressure passages having a minimum channel length. In this manner, hydraulic fluid contained within the respective variable pressure chambers which communicate with the associated variable pressure passages can be rapidly displaced through the valve mechanism, thus preventing an operational lag in terminating the brake action in a favorable manner.

Abstract: In a brake booster comprising a control rod (30) actuating a booster mechanism (34, 20a, 28a) by way of a plunger (28), in order to exert a boosting force on a piston (20) acting on a push rod (46) via a reaction disc (48) made of a deformable material, an adjustable prestress is applied to the latter. This result can be obtained particularly by way of a cover (50) capping a plate (46b), formed at the rear end of the push rod, and the reaction disc (48). The prestress thus applied to the disc makes it possible to adjust the play existing between the latter and the front end of the plunger (28) and consequently the jump of the booster.

Abstract: A brake booster includes at least two pairs of constant pressure chambers and variable pressure chambers defined within a shell. A clearance is defined between a stepped end face of a valve body which is disposed within the shell and a power piston which is mounted on the valve body at a location rearward of the stepped end face. The clearance is utilized to provide a communication between the constant pressure chambers, thereby allowing a reduction in the axial size of the valve body.

Abstract: A vacuum brake booster in which the guiding sleeve (14) for the push rod (29) has an annular ring which defines a cylindrical guiding surface (22) and is guided, in axial movements of the guiding sleeve, by a guide bore in the housing (10) of the control valve.

Abstract: A plunger (52) having a cylindrical body with a smooth surface (61) thereon which joins an semi-spherical atmospheric seat (62) with a conical surface (60) to define with a section (31) of bore (30) a flow path through which air is communicated from the environment to a rear chamber (20) without the creation of noise. The smooth surface (61) is made of a porous material (51) that absorbs sounds without substantially effecting the flow of air.

Abstract: A pneumatic boost device includes a booster input including a manually actuatable upstream pusher and a downstream pusher positioned such that the movement of the upstream pusher towards the piston causes the upstream pusher to contact and move the downstream pusher toward the piston. A compressed gas is supplied to the cylinder such that the piston is moved in a direction away from the booster input by a system including a gas flow path having a first check valve, the first check valve being seatable on a seat moving with the downstream pusher. Movement of the downstream pusher thus applies a gas pressure to the piston which moves by an amount corresponding to that of the upstream pusher. The downstream pusher has a piston in the additional cylinder. Another gas flow path has a second check valve, the second check valve being seatable on a seat moving with the upstream pusher by movement of the upstream pusher toward the piston.

Abstract: A parking sustainer which allows a vehicle to be maintained parked by continuing a braking action if the depression of a brake pedal is terminated. An open/close valve is disposed in a liquid pressure discharge passage usually provided in a liquid pressure booster, and control means closes the open/close valve when a set of conditions to maintain the vehicle parked are satisfied. The provision of the open/close valve in the discharge passage of the booster eases the space requirement for its mounting and facilitates a maintenance inspection or repair.