Abstract: In a master cylinder, a supply passage for supplying operating liquid from a reservoir (2) to a pressure chamber (6) is provided in a cylinder body (3) coupled with the reservoir. A bypass passage (37) for bypassing the supply passage and connecting the reservoir and the pressure chamber is further provided, and a check valve (34) adapted to open when a pressure in the pressure chamber is lower than that in the reservoir is disposed in the bypass passage. A valve case (38) containing a valve body (41) of the check valve includes a valve seat (40) and a cylindrical wall (45) for slidably guiding the valve body which are integrally formed as a single member.

Abstract: The invention relates to a motor vehicle master cylinder (1). More specifically, the invention relates to a piston (4, 5) of the master cylinder which has a first indentation (24) and a second indentation (27), which indentations are formed upstream of a port (13, 14) of the piston. The first indentation and the second indentation delimit a space within which hydraulic brake fluid can be stored so that it can be tapped off by an auxiliary braking device of the E.S.P. type.

Abstract: The invention relates to a master cylinder (1) with reduced free travel (23). Current master cylinders have a free travel during the displacement of a piston (6) in a bore (5) of a master cylinder body (3). Such a free travel may be reduced with the aid of a frustoconical portion (24) in the piston, an orifice (14) for communication of hydraulic fluid being situated on said inclined wall, a gap (26) between the inclined wall and an inner wall (12) of the bore allowing a passage for hydraulic fluid capable of filling a pressure chamber (4). However, such inclined walls create a change in the slope of an outer wall (29) of the piston, this change being able to cause a separation of an inner lip (19) of a sealing cup (17). To prevent this separation, the invention provides that the inclined wall forms a convex rounded surface (32).

Abstract: Our problem relates to a master cylinder with a U-shaped seal. Our goal is to avoid defective bleeding of hydraulic braking systems. The defects arise out of the fact that the vacuum causes the lips of the seal (21) to stick together and to stick against the wall (41). To achieve this, reliefs (42) will be created on one wall (44) of one lip (28) facing the other lip (27) and on the edge face (50) of this same lip. These reliefs will prevent the lips from sticking tightly to one another and to the wall facing the edge face of the lips. This lack of sticking will prevent a vacuum from being created between the two lips and between the edge face of the lips and the wall (41). As a result, the seal will be able to return to a position in which bleeding can be performed effectively.

Abstract: According to the plunger-typed master cylinder of the invention, because deformation of seal cups fitted in the hydraulic pressure chambers with the pistons (primary piston and floating piston) inserted is minimized, that is, the deformation of the inner flange being in contact with pistons does not substantially affect the outer flange being in contact with hydraulic pressure chambers when the master cylinder is in operation, it is possible to prevent deterioration in the performance of passing or stopping oil due to the deformation of seal cups and durability.

Abstract: A master cylinder assembly for a hydraulic actuation system for a handlebar-steered vehicle including a fluid cavity having an adjustable length. The master cylinder assembly generally includes a housing, a piston assembly, an actuator and an adjuster. The housing is mountable to a frame member and includes a chamber having a fluid cavity with first and second regions. The first region is in fluid communication with the hydraulic actuation system. The piston assembly includes a piston slidably disposed within the fluid cavity. The actuator is operatively connected to the housing and operatively connected to the piston to slidably displace the piston between an open fluid circuit position permitting fluid flow between the first and second regions and a closed fluid circuit position blocking fluid flow between the first and second regions. The adjuster is operatively connected to the housing to adjust a length of the fluid cavity.

Abstract: A master cylinder 1, especially for a controlled brake system, includes at least one piston 3, 4; 53, 54 displaceable in a housing 2, which is sealed in relation to a pressure chamber 7, 8 by means of a sealing element 5, 6 arranged in an annular groove 23, 24 of the housing 2, said pressure chamber being connectable to an unpressurized supply chamber 11, 12 by means of transverse bores 9, 10; 50, 51 provided in the piston 3, 4; 53, 54. Several recesses 15, 16, 17 are arranged on an inside surface 13, 14; 59, 60 of the piston 3, 4; 53, 54 into which the transverse bores 9, 10; 50, 51 open.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which is slideably mounted at least one axial piston, of the type in which the bore (14) comprises two seals, front and rear, interposed between the piston and the bore (14), characterized in that it comprises at least one wide groove (66, 68) which is formed in the bore (14) in front of a groove (70, 72) for retaining the front seal, which extends at least in part around the piston, and which communicates with said retaining groove (70, 72) and the hole in the piston, in order to allow resupplies to occur with a high flow rate.

Abstract: A sealing element seals a pressure piston which is movably arranged in a housing of a brake cylinder. The sealing element may be inserted into a ring-shaped groove which is provided in the housing. The sealing element includes an outer sealing lip for contact with a floor of the ring-shaped groove, an inner sealing lip for contact with the pressure piston, and a sealing element back. At least one non-sealing spacer element is provided on the sealing element back.

Abstract: A cup seal 21 includes a base portion 21a, an inner circumferential lip 21b slidingly contactable with a plunger 19 and an outer circumferential lip 21c contactable with the bottom surface 26a of the seal groove 26. Further, on the cup seal 21, there are provided elastic projections 21d projecting from the outer circumferential side leading end of the inner circumferential lip 21b toward the cylinder hole bottom portion. The length of the cup seal 21 from the base end face 21e to the leading end portions 21f is set longer than axial length of the seal groove 26. When the cup seal 21 is fitted into the seal groove 26, force is imparted on the inner circumferential lip 21b toward the cylinder hole inner circumferential direction to energize the inner circumferential lip 21b toward the piston all the time.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that front faces of the grooves (70, 72) are configured at least in part as a slope.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that the seals (30, 34) comprise central lips of reduced cross section.

Abstract: An object of the present invention is to provide a master cylinder capable of controlling an increase in an intruding amount of a cup seal while relieving a stress concentration therein to thereby prevent the cup seal from being damaged. Provided is a master cylinder in which a piston is moved in slidable contact with an inner circumference of a cup seal held in a cylinder main body so as to pressurize a brake fluid in a pressure chamber formed of the piston and the cylinder main body, wherein an annular wall configured integrally with the cylinder main body is provided behind the cup seal. Further, a chamfered portion having a curved shape in a cross-section taken along a diameter direction of the cylinder main body is provided between the annular wall and a cylinder wall to which the piston is facing.

Abstract: A master cylinder of a brake is disclosed. The master cylinder includes a cylinder body connected with an oil tank and defining therein a first pressure chamber and a second pressure chamber, which are separated from each other by a partition, a first piston to perform reciprocating movements in the first pressure chamber, a second piston to perform reciprocating movements in the second pressure chamber, a first return spring to elastically support the first piston in the first pressure chamber, and a second return spring to elastically support the second piston in the second pressure chamber. The first piston has a plurality of recesses formed at one end thereof to assure smooth supply of oil during braking. The master cylinder has the effects of assuring smooth supply of brake oil during braking, and preventing fluctuation of a piston therein.

Abstract: A master cylinder comprising a large diameter pressurizing chamber and a small diameter hydraulic chamber, a control valve device in which a control valve body releases a hydraulic pressure in the large diameter pressurizing chamber to a reservoir side such that the hydraulic pressure in the large diameter pressurizing chamber is gradually reduced in accordance with a rise in a hydraulic pressure in the small hydraulic chamber, and a check valve device comprising a check valve chamber communicating with an relief passage, which releases a hydraulic pressure in the large diameter pressurizing chamber to the reservoir via the control valve device, and with a small diameter hydraulic chamber, respectively, and a check valve body accommodated in the check valve chamber for permitting flow of a brake fluid from the relief passage to the small hydraulic chamber, and for preventing flow of the brake fluid in a reverse direction.

Abstract: A master cylinder assembly for a hydraulic actuation system for a handlebar-steered vehicle. The assembly includes a housing mountable to a frame member of the handlebar-steered vehicle and having a chamber including a fluid cavity with first and second regions. The first region is in fluid communication with the hydraulic actuation system. A piston is slidably disposed in the fluid cavity. An actuator is operatively connected to the housing and operatively connected to the piston to slidably displace the piston between an open fluid circuit position and a closed fluid circuit position. A first seal is disposed on either the piston or a wall of the fluid cavity. The first seal is configured to be in sealing engagement between the fluid cavity and the piston with the piston in the closed fluid circuit position to block fluid flow between the first and second fluid cavity regions.

Abstract: A master cylinder that can prevent impairment of a piston seal, and a method of producing the master cylinder are provided. A master cylinder has a circumferential groove (47) in which a piston seal is provided, the piston seal having an outer circumference which enables operating fluid to be supplied, and a communication groove (96) which opens into the circumferential groove (47) and extends from the circumferential groove (47) toward a bottom portion of a cylinder body (15) to connect a pressure chamber and the circumferential groove (47). The communication groove (96) is formed with its center made eccentric relative to the center of the circumferential groove (47). A chamfered portion (100) is formed over an entire extent of a corner portion formed by the circumferential groove (47) and the communication groove (96), along a circular path concentric with the communication groove (96).

Abstract: A master cylinder assembly for a bicycle disc brake having a housing defining a cylinder, a piston received in the cylinder, a lever pivotably attached to the housing, and an adjustment guide body that is operatively associated with the piston. The piston is moveable within the cylinder between a select starting position and a pressurized position. The lever is operatively associated with the piston to move the piston from the select starting position to the pressurized position as the lever is pivoted between a rest position and a fully-actuated position. The adjustment guide body is pivotable between a first position and a second position for adjusting the select starting position of the piston.

Abstract: A method of adjusting a lever actuated bicycle hydraulic disc brake master cylinder. The disc brake master cylinder has a housing defining a cylinder having first and second ends and a port communicating with a fluid reservoir between the first and second ends. A piston is received in the cylinder and the piston has a seal having a leading seal edge between the piston and the cylinder. The lever is operatively associated with the piston to move the piston from an unactuated position with the leading seal edge a select distance between the port and the first end of the cylinder to an actuated position between the port and the second end of the cylinder.

Abstract: A brake apply master cylinder includes a body and a piston assembly. The body includes a bore. The bore has a longitudinal axis, a closed front end, a primary fluid outlet fluidly connectable to a primary brake circuit, and a secondary fluid outlet fluidly connectable to a secondary brake circuit. The piston assembly includes a single brake apply piston positioned in the bore. The piston assembly fluidly divides the bore into a primary fluid chamber in fluid communication with the primary fluid outlet and a secondary fluid chamber in fluid communication with the secondary fluid outlet. Another brake apply master cylinder includes a body, a piston assembly, and a return spring assembly. The return spring assembly is positioned in the bore of the body and extends from the closed front end of the bore to a return-spring seat of a single brake apply piston of the piston assembly.

Abstract: In a cup seal of the present invention, an inner lip (27b) is pressed into close contact with a piston (9) and an outer lip (27c) is pressed into close contact with a bottom wall (26a) of a concavity (26) by fluid pressure developed in a fluid pressure chamber (11) when the piston (9) moves forward. Therefore, fluid pressure is sealed. When the piston (9) is retracted, the outer lip (27c) is deflected inwardly and is thus spaced apart from the bottom wall (26a) of the concavity (26). Hydraulic fluid of a reservoir is supplied to the fluid pressure chamber (11) through a first communication path (22), grooves (27e), and the space between the outer lip (27c) and the bottom wall (26a). As mentioned above, the inner lip (27b) has only the sealing function, while the outer lip (27c) has both the sealing function and the pumping function and ensures sufficient fluid supply by the grooves.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that the seals (30, 34) comprise central lips of reduced cross section.

Abstract: Brake master cylinder (10) for a motor vehicle, of the type which comprises a substantially axial body (12) inside a bore (14) of which at least one axial piston is slideably mounted, of the type in which the bore (14) comprises two seals, front (30, 34) and rear, interposed between the piston and the bore (14), the seals (30, 34) comprising three radially concentric lips accommodated in grooves (70, 72) in the bore (14), characterized in that front faces of the grooves (70, 72) are configured at least in part as a slope.

Abstract: A master cylinder for a bicycle hydraulic disc brake comprises a housing defining a cylinder, the cylinder having a first and a second end along its axis. A hydraulic fluid reservoir has a port between the hydraulic fluid reservoir and the cylinder, the port having an opening between the first and second cylinder ends. A piston having a seal resides in the cylinder with the seal between the piston and the cylinder. The seal has a leading seal edge with the leading seal edge being movable solely between the first cylinder and the port opening to vary the dead band distance between the leading seal edge and the port opening with the piston in a starting position. A lever is pivotably associated with the housing and operatively associated with the piston for moving the piston within the cylinder between the starting and a pressurized position as the lever is actuated between a rest position and an actuated position.

Abstract: A master cylinder assembly for a bicycle disc brake having a housing defining a cylinder, a piston received in the cylinder, a lever pivotably attached to the housing, and an adjustment guide body that is operatively associated with the piston. The piston is moveable within the cylinder between a select starting position and a pressurized position. The lever is operatively associated with the piston to move the piston from the select starting position to the pressurized position as the lever is pivoted between a rest position and a fully-actuated position. The adjustment guide body is pivotable between a first position and a second position for adjusting the select starting position of the piston.

Abstract: Disclosed is a master cylinder comprising a stepped cylinder having a large diameter cylinder portion and a small diameter cylinder portion, a stepped piston inserted into the stepped cylinder, a reverse-flow-checking opening and closing portion for partitioning the inside of the stepped cylinder into a large diameter pressurizing chamber and a small diameter hydraulic chamber, and a control valve device in which a control valve body releases a hydraulic pressure in the large diameter pressurizing chamber to a reservoir side such that the hydraulic pressure in the large diameter pressurizing chamber is gradually reduced in accordance with a rise in a hydraulic pressure in the small hydraulic chamber, the master cylinder characterized in further comprising a check valve device comprising a check valve chamber communicating with an relief passage, which releases a hydraulic pressure in the large diameter pressurizing chamber to the reservoir via the control valve device, and with a small diameter hydraulic cham

Abstract: A master cylinder of a brake is disclosed. The master cylinder includes a cylinder body connected with an oil tank and defining therein a first pressure chamber and a second pressure chamber, which are separated from each other by a partition, a first piston to perform reciprocating movements in the first pressure chamber, a second piston to perform reciprocating movements in the second pressure chamber, a first return spring to elastically support the first piston in the first pressure chamber, and a second return spring to elastically support the second piston in the second pressure chamber. The first piston has a plurality of recesses formed at one end thereof to assure smooth supply of oil during braking. The master cylinder has the effects of assuring smooth supply of brake oil during braking, and preventing fluctuation of a piston therein.

Abstract: A piston seal is provided in a circumferential groove formed in a cylinder body. The piston seal is capable of sealing a pressure chamber, which supplies fluid pressure to a discharge passage, from a supply passage, which communicates with a reservoir. The piston seal comprises: an annular base portion; an inner circumferential lip portion projecting from an inner circumferential side of the base portion and being in slidable contact with an outer circumferential surface of a piston; an outer circumferential lip portion projecting from an outer circumferential side of the base portion and being in abutment with the circumferential groove of the cylinder body; and an intermediate projecting portion which is formed between the inner circumferential lip portion and the outer circumferential lip portion of the base portion and which is projected beyond the outer circumferential lip portion. Cutout grooves are formed on a tip side of the intermediate projecting portion.

Abstract: A hydraulic brake master cylinder is provided that is compact and light in weight. The master cylinder has a reservoir shape that provides increased reservoir expansion volume. The master cylinder also provides gear shifter operation clearance and a comfortable lever that allows easy adjustment without the use of tools. The lever has defined increments of adjustment which make it easy to use. The invention also includes a method of bleeding air from the system without requiring reorientation of the master cylinder. The retention methods for the various lever embodiments shown allow for easy and inexpensive retention of the lever and also provide for reduced overall weight and cost.

Abstract: A master cylinder includes a piston received in a cylinder body and formed with piston ports. An annular groove is formed in the inner periphery of the piston in its area where the piston ports are formed. An arcuate plate is received in the annular groove. A sleeve is inserted into the arcuate groove to retain the arcuate plate in the annular groove. A gap as a fluid passage is defined between the arcuate plate and the inner surface of the annular groove. A pressure chamber defined in the cylinder body communicates with a communication passage communicating with a reservoir through the above gap, cutouts of holes formed in the arcuate plate and holes formed in the sleeve. When hydraulic fluid flows rapidly from the pressure chamber toward the reservoir, the arcuate plate is adapted to elastically and radially expand, thus closing some of the piston ports.

Abstract: A master cylinder (1) having a bore (3) fitted with at least one piston (4, 5) and at least one seal (19, 20, 21, 22). The seal (19, 20, 21, 22) is partially stiffened by a reinforcement member (25). In order to retain the piston (4,5) in the bore (3) a groove (31) is located on a circumference of the piston (4,5) against which the sealing member (25) bears with the piston (4,5) in a rest position to retain the piston (4,5) in bore (3).

Abstract: A master cylinder 1, especially for a controlled brake system, includes at least one piston 3, 4; 53, 54 displaceable in a housing 2, which is sealed in relation to a pressure chamber 7, 8 by means of a sealing element 5, 6 arranged in an annular groove 23, 24 of the housing 2, said pressure chamber being connectable to an unpressurized supply chamber 11, 12 by means of transverse bores 9, 10; 50, 51 provided in the piston 3, 4; 53, 54. Several recesses 15, 16, 17 are arranged on an inside surface 13, 14; 59, 60 of the piston 3, 4; 53, 54 into which the transverse bores 9, 10; 50, 51 open.

Abstract: A large-diameter bore portion is formed in a portion defining a pressure chamber in a cylinder body on a side opposite to a circumferential groove relative to a slidable inner-diameter portion. A communication groove capable of allowing communication between the circumferential groove and the large-diameter bore portion is formed in an upper portion of the slidable inner-diameter portion. A point of maximum depth of the communication groove is located radially outward of a bottom of the circumferential groove. The master cylinder of the present invention is capable of preventing the supply of a brake fluid from being restricted in an evacuation process, and enables a reduction in length to be machined of the communication groove, thus reducing the time for machining and suppressing an increase in cost.

Abstract: A hydraulic cylinder includes a housing having a fluid connection for connecting to a hydraulic system and an after-running connection for connecting to a fluid after-running vessel, and a piston which is axially displaceable in the housing to define a variable pressure space having a gas collecting portion, the piston being fixed against rotation in the housing and having at least one after-running groove which is oriented substantially toward the gas collecting portion. A primary seal arranged in the housing and receiving the piston therethrough is bridged by the after-running groove when the piston is in an extended end position, whereby the gas collecting portion of the pressure space communicates with the after-running connection when the piston is in the extended end position.

Abstract: A hydraulic cylinder, in particular a master cylinder for a hydraulic clutch actuation system for motor vehicles, has a housing having a cylinder wall, in which a piston is slidably received to seal off the pressure chamber, whereas the pressure chamber in a rest position of the piston is connected to an after-running region by equalization grooves of an after-running device. The cylinder wall of the housing is provided with profiled cut-outs on its piston-side end at least in a lower region in the installed position of the cylinder, which cut-outs each have an upper boundary surface which in the installed position of the cylinder rises up to the equalization grooves of the after-running device.

Abstract: To provide a plunger type master cylinder capable of reducing invalid stroke and preventing residual pressure without impairing durability of a seal ling (70). A piston (91) of the master cylinder has a recess (93) at its outer peripheral surface and a relief port (900) in its recess (93). The seal ring (70) has a seal coupling part (70s) on the inner periphery of the distal end part of an inner peripheral lip (701). The seal coupling part (70s) is located at the opening of the relief portion (900) on the piston (91) side when the brake is in a non-operating position. The distance between said seal coupling part (70s) and said relief port (900) is short. The seal ring (70) additionally has first and second projection parts (7006, 7002) on the inner peripheral surface of the inner peripheral lip (701). By this, a flow passage for working fluid can be obtained on the inner periphery side of the inner peripheral lip (701).

Abstract: The present invention relates to a tandem master cylinder including two plunger pistons and its object is to design the cylinder as simple as possible and to render its assembly as economical as possible. This object is achieved by inserting circumferential annular grooves directly into the housing of the master cylinder in order to accommodate sealing sleeves, namely both the primary seal and, in an improvement of the invention, the primary seal of the piston at the end of the push rod as well as the secondary seals of both pistons. Collecting annular grooves at the level of the connecting outlets for the compensating reservoir are further favorable aspects of the invention.

Abstract: Apparatus for controlling brakes in bicycles and the like, to be used, in particular, for disc brakes mounted on bicycles, with a pump (8) connected with a relevant reservoir (88) for the fluid of the hydraulic circuit, and comprising a piston (89) sliding within a relevant chamber (80) provided with one or more ports (83, 84) for connection with said reservoir (88), said piston being so shaped as to close/open said ports (83, 84) upon its displacement along said chamber (80), the apparatus being characterized in that the idle stroke of the piston (89) inside the said chamber (80) is adjustable by a rotation of the same piston (89) about its longitudinal axis.

Abstract: Apparatus for controlling a hydraulic circuit to be used for operating hydraulic clutches with a pump (8) connected with a relevant reservoir (88) for the fluid of the hydraulic circuit and comprising a piston (89) sliding within a relevant chamber (80) provided with one or more ports (83, 84) for connection to said reservoir (88), the said piston being so shaped as to close/open the said ports (83, 84) upon its stroke along said chamber (80), apparatus being characterized in that the idle stroke of the piston (89) within said chamber (80) is adjustable through a rotation of the same piston (89) about its longitudinal axis.

Abstract: A master cylinder includes a primary cup received in a groove formed in the inner wall of the cylinder body. Projections are formed on a radially inner portion of the cup so as to protrude forwardly from the front end of the radially inner portion. The projections are adapted to be pressed against the front end wall of the cup-receiving groove and elastically deformed under a pressure difference produced between the front and rear ends of the cup when the piston is returned quickly, allowing the cup to advance in the cup-receiving groove. When the cup advances in the groove, a fluid passage is defined between a base portion of the cup and the rear end wall of the groove.

Abstract: The piston in the master cylinder of a hydraulic system of the kind that is used particularly in motor vehicles is made of a duroplastic polymer material.

Abstract: A master cylinder includes a primary piston and a secondary piston, each formed with piston ports which include two different kinds of ports, i.e. first ports for ensuring communication between a reservoir and a pressure chamber of the master cylinder, and second ports through which brake fluid is sucked from the reservoir during automatic break control. The second ports are greater in number than the first ports and are positioned forwardly of the first ports so that the second ports are closed by primary cups which are provided on the inner wall of the cylinder body so as to be in sliding contact with the respective pistons before the first ports when the respective pistons are advanced. An annular wall having a greater inner diameter than the outer diameter of the pistons is formed on the inner wall of the cylinder body to support the back of each of the primary cups. An annular groove is formed in each piston so as to communicate with the first ports.

Abstract: This invention relates to a master cylinder of the so-called “penetration” type, in which a cup (3), which is fitted inside a groove (11) of the master cylinder, bears on the wall (20) of a piston (2) in a sealing manner, and in which such wall (20) is provided with main resupply ports (51). According to the invention, the wall (20) of the piston (2) also comprises secondary resupply ports (52) having a smaller size than that of the main resupply ports (51) and disposed farther from the bottom part (33) of the cup (3), and achieving an outstanding static resupply of the master cylinder with brake fluid, with a reduced dynamic dead stroke.

Abstract: A brake master cylinder includes a cylinder body having a circumferential groove formed therein. A primary cup is received in the groove and supported axially by a rear wall defined by the groove. A primary piston is inserted in the cylinder body in sliding contact with the primary cup. The rear wall has a radially inner surface formed with a plurality of grooves. A passage leading to a reservoir is provided in the rear of the grooves. The piston is formed with radial through holes corresponding to the grooves. When the piston is at the return end of its stroke, the pressure chamber defined in the cylinder body can communicate with the reservoir through the radial through holes, the grooves and the passage.

Abstract: A master cylinder includes a cylinder body and a piston slidably inserted in the cylinder while kept in slide contact with two cup members both fitted in the inner surface of the cylinder body to seal the gap between the piston and the inner surface of the cylinder body. On its radially inner surface, the cylinder body is formed with first to third piston guide portions. Each piston guide portion is formed with an odd number of grooves arranged at circumferentially equal distances. Each groove of each piston guide portion axially aligns with the corresponding grooves of the other piston guide portions. The circle including the bottoms of the grooves of the first guide portion has a diameter equal to or smaller than the rear opening of the cylinder body. The grooves of the first guide portion have a width gradually decreasing toward the front end thereof.

Abstract: A master cylinder apparatus for a BBW system is provided, which eliminates a risk of brake delay, even with the use of a plunger-type master cylinder, and which therefore is able to achieve a reduction in size of a master cylinder. The master cylinder apparatus comprises a tandem-type master cylinder connected to wheel cylinders through fail-safe valves and a stroke simulator for ensuring a desired stroke of a brake pedal upon receiving a brake fluid introduced from a fluid pressure chamber in the master cylinder. The master cylinder is arranged in the form of a plunger-type master cylinder in which cup seals are provided on an inner surface of a bore of the cylinder body. A spring force of a second return spring for a secondary piston is set to be larger than that of a first return spring for a primary piston. A retracted position of the secondary piston is limited by a stopper pin extending through an oblong hole formed in the secondary piston.

Abstract: This invention relates to a master cylinder (10), inside a bore (14) of which two axial primary and secondary pistons (16, 18), are slidingly fitted, and in which at least one sealing means (48, 50) is disposed in contact with each piston, defining a supply chamber (56, 60) and a pressure chamber (58, 62). Each piston (16, 18) comprises a bore (78, 80), open in the direction of the front pressure chamber (58, 62), and the piston (18) comprises a valve-forming through-hole (88), opening into its periphery and into its bore (80), in order to isolate the front pressure chamber when it passes beyond the sealing means so as to produce a braking pressure, characterised in that the front pressure chamber (62) associated with at least one piston (18) comprises at least one tubular cylindrical element (90) extending axially outside the piston (18) and rearwards of the sealing means (50) for the obturation of the through-hole (88) according to a reduced stroke (Cm2).

Abstract: A master cylinder includes a cylinder main body forming a piston mount space and a piston mounted in the cylinder main body. An auxiliary supplying/discharging passage communicating sideways with the piston mount space is provided at a longitudinally middle portion of the cylinder main body. The inner circumferential surface of the cylinder main body and the outer circumferential surface of the piston are shaped such that a communication path communicating a pressure chamber near a supplying/discharging opening and the auxiliary supplying/discharging passage is formed at the outer side of a seal ring mounted on the piston with the piston moved back to a rearmost position most distanced from the supplying/discharging opening. The position of the piston and the pressure in the pressure chamber can be stabilized when the piston is located at a rearmost position from the supplying/discharging opening.

Abstract: A master cylinder for a hydraulic disc brake includes a housing defining a cylinder, the cylinder having a first and second end along its axis. A piston is received in the cylinder and has a radial seal between the piston and the cylinder. A lever is pivotably associated with the housing for pivoting between a rest position and an actuated position relative to the housing. A push rod is operatively associated with the piston and the lever to move the piston axially within the cylinder as the lever is actuated between the rest and actuated positions. A threaded engagement between a first end of the push rod and the lever is configured to cause movement of the rest position of the lever relative to the housing when a rotating force is applied to the push rod causing axial rotation of the push rod. An indexing structure is operatively associated with the push rod for providing index axial rotation of the push rod upon application of the rotating force to the push rod causing axial rotation of the push rod.

Abstract: A master cylinder comprises a cylinder body in a cylindrical form having one end closed and including a discharge passage and a supply passage for a brake fluid, the supply passage being communicated with a reservoir. A piston is slidably disposed in the cylinder body, so as to form a pressure chamber for supplying a fluid pressure to the discharge passage. A piston seal is provided in a circumferential groove formed in the cylinder body, which has an inner circumferential surface thereof in slidable contact with the piston and is capable of sealingly disconnecting the supply passage and the pressure chamber. The cylinder body includes a communication groove which opens into the circumferential groove and extends from the circumferential groove toward the closed end of the cylinder body to thereby connect the circumferential groove and the discharge passage. The communication groove is formed outwardly beyond a bottom surface of the circumferential groove relative to a radial direction of the cylinder body.