Abstract: A cylinder body 60 of a wheel cylinder assembly 6 for expanding a pair of brake shoes 3 and 4 by a pair of pistons 31 and 32 brought into contact with the respective brake shoes has a shape of a single straight pipe with both ends which are opened. The cylinder body 60 includes a first cylinder portion 35 for the one 32 of the pistons and a second cylinder portion 34 for the other 31 of the pistons. A valve seat 43 of a control valve 39 is arranged between the cylinder portions 34 and 35.

Abstract: A drum brake backplate assembly including a wheel cylinder (30) having a tubular body (31) having an axially extending bore (32) within which two brake shoe operating pistons (33) are in sealed sliding contact to define a working chamber (48) therebetween. The pistons are displaceable away from each other along the bore on pressurisation of the working chamber and the body located on an associated brake-backplate (44) by quick-attach means (46).

Abstract: A device and method to improve the bleeding of air from a brake cylinder usable in a drum brake. A first cylinder cavity 3 and a second cylinder cavity 4 are bored in the upper and lower sections respectively of the cylinder body 2, and a first piston 31 and a second piston 41 are housed to stroke within said cylinder cavity 3 and cylinder cavity 4 respectively, wherein piston 31 and a partition 21, separating said cylinder cavity 3 and cylinder cavity 4, form a first fluid chamber 32, and piston 41 and said partition 21 form a second fluid chamber 42. The cylinder also comprises at least one grooved fluid line 52 or an interior fluid line 53 to enable passage between said fluid chambers 32, 42; a brake fluid inlet line 51 that brings brake fluid into the second fluid chamber 42; and a brake fluid outlet line 54 that discharges the brake fluid into the first fluid chamber 32.

Abstract: A drum-type brake actuator provides increased force transmission efficiency and assembly simplicity. An anchor carries two pistons which are moved to apply a brake shoe by the cooperative operation of a lever and strut arrangement. The utilization of three pivot joints in a simplified mechanism results in high efficiency output.

Abstract: A vehicle braking system has a master cylinder, a first brake associated with a front wheel of the vehicle and a second brake (11) associated with a rear wheel of the vehicle, the master cylinder being connected to the first and second brakes in a common circuit. The second brake includes brake actuator (10) with a valve (30, 35) which will vary the rate at which fluid pressure is applied to the brake actuator (10) at a predetermined brake pressure, a spring loaded lever (50) acts on the valve (30, 35) to set the predetermined pressure at which the rate of application of pressure is varied and a linkage mechanism (70) varies to loading of the lever (50) to vary the predetermined pressure in proportion to the load applied to the rear wheel with which the brake (11) is associated.

Abstract: The present invention provides a vehicle wheel cylinder for a drum type brake. The sealing boot which seals the wheel cylinder frame and piston is provided in a preferred embodiment with annular rings which help protect the integrity of the sealed relationship of the annular boot with the bore of the wheel cylinder against damage which can be caused by contact of the sealing boot with a web of a brake shoe.

Abstract: The invention relates to a wheel cylinder for a drum brake, comprising a body (2) provided with a longitudinal bore, two pistons (4,6) sliding in opposite directions outwards in the bore under the action of a pressurized fluid introduced between the pistons against the return springs of the shoes of the brake, and a mechanism limiting the return travel of the pistons when the pressure is released. According to the invention, the mechanism limiting the travel consists of two resilient rings (16, 18), at the outer periphery of each of which a friction mechanism (20, 22) is disposed, and which are disposed, respectively, in an annular groove (24, 26) made in each of the pistons so as to provide a specific axial clearance (d) between a radial wall of the groove and the adjacent side of an assembly consisting of the resilient ring and the friction mechanism, this assembly being provided in order to resist the return springs of the brake shoes in a drum brake.

Abstract: A brake actuator has a body containing a pair of brake-applying members which may be actuated hydraulically to separate the friction elements of a brake into engagement with a rotatable braking surface. The members are interconnected by a mechanism in the form of a shaft of which respective end portions are provided with reversible threaded portions of opposite hand which engage corresponding threads within the members, the shaft being constrained against axial movement between bearings. Any excess movement of one of the members relative to the other is transmitted to that other member such as to cause an opposite and proportional force on the other member to substantially equalize the wear rates on the friction elements.

Abstract: A piston and cylinder assembly for a vehicle hydraulic system has a retaining device comprising an insert acting between a piston and the cylinder bore in which it works, the insert having a releasable frictional engagement in the bore and acting as an abutment to hold the piston in its retracted position to maintain the effective length of the assembly at a predetermined value for installation, until the assembly is operated hydraulically. The assembly may be an actuator for a self-energizing disc brake, or a slave cylinder for a vehicle clutch system.

Abstract: A hydraulically actuated wheel brake with a built-in control device comprising a brake piston including two pressure surfaces each of which defines a different one of two working chambers. The pressure fluid inlet is connected directly to one of the two working chambers and via a valve to the other of the two working chambers, the valve being actuatable upon attainment of a predetermined value of inlet pressure. The brake piston has a step in its outer periphery whose surface provides one of the two pressure surfaces. The piston is guided exclusively at its outer periphery in a cylindrical bore of a housing. Since only two parts are disposed concentrically in each other, there results ease of manufacture and a minor susceptibility to failure.

Abstract: A self adjusting wheel cylinder for a drum brake including a brake drum and a brake shoe for exerting braking pressure on the drum with a shoe gap formed therebetween comprising a cylinder including an opening therein, hydraulic piston slidably mounted in the opening for activating the brake shoe upon movement in one direction, and for releasing the brake shoe upon movement in the other direction, and multiple adjusting screws within the cylinder for automatically adjusting the limit of movement of the piston in response to changes in the shoe gap of the brake, the multiple adjusting screws including a spindle having external screw-threads on both ends, the spindle is threadably mounted within the piston to one end thereof, and has a pair of multiple drive screws on the other end of the spindle for defining a fixed movement limit of the piston.

Abstract: A brake device for use in an arm of a robot or manipulator cmprises a brake drum, a lever pivotally supported at its intermediate portion, a brake shoe provided on the lever between its pivotally supported point and its one end, a pneumatic actuator axially contractible upon applying internal pressure thereinto and having a movable end connected to the one end or the other end of the lever, and a spring connected to one end of the lever not connected to the actuator so as to operate to elongate the actuator. This brake device is remarkably small-sized and of light-weight and consumes only small amount of fluid pressure to contribute economy of energy in comparison with prior art brake devices.

Abstract: An expanding mechanism for an interior shoe drum brake, such as a simplex "expander-wedge" type brake, comprises a cylinder housing affixed to a brake support, coaxially mounted pressure pistons slidable in the housing, expander members adjoining the respective pressure pistons and adjusting screws threaded into the pressure pistons which screws engage flange members of the respective brake shoes via interposed pressure pieces. To avoid local pressure peaks, the exterior ends of the adjusting screws are provided with part spherical indentations and the pressure pieces have complementary part spherical inner ends accommodated therein. The outer ends of the respective pressure pieces are connected to the respective flange members of the brake shoes by groove-type guides perpendicular to the axis of the brake drum.

Abstract: A drum brake assembly having a wheel cylinder mounted on arms of a center guide backing plate by means of notches receiving the arms. The cylinder has pistons with low drag O-ring seals in grooves configured to provide seal forces which are aided by brake actuating pressure to assure sealing action. Wiper seals within the wheel cylinder are used in place of boots.

Abstract: A drum brake hydraulic wheel cylinder assembly comprises a pair of piston assemblies and an abutment member. The piston assemblies are of the kind comprising an adjustable variable length tappet assembly having interengaged screw-threaded components. To enable thrust to be transmitted from one adjacent brake shoe to the other, i.e. for parking purposes, the abutment member is slidable in the cylinder bore against a spring centering device.

Abstract: An actuator for a shoe drum brake has a body containing a tappet engaging one of a pair of brake shoes, and a split tappet of which the outermost piston engages the other brake shoe. A mechanical wedge actuator acts between the tappets for emergency and parking operation. The piston cooperates with an automatic adjuster of which a component normally engages an abutment member which bears against a shoulder within the body to isolate the adjuster from the piston of the split tappet and thereby from the other tappet.

Abstract: A wedge actuated drum brake assembly uses a wedge-shaped actuating rod and a roller cage slidably mounted thereon to transmit actuating forces from a fluid pressure actuator to a pair of friction elements. The actuating rod and roller cage are provided with a compression spring between the rod and the roller cage and an extension spring between the roller cage and the housing within which the actuating rod and roller cage are movably mounted. The extension spring opposes the compression spring during initial movement of the actuating rod to thereby cancel the spring forces acting on the cage. A flexible boot interconnects the rod and the wall of the housing and includes a bead that is clamped with the end coil of the extension spring between a shoulder on the housing and a portion of the fluid pressure actuator that extends into the housing.

Abstract: The brake comprises a torque control valve comprising a main piston which cooperates via a bearing piece with a shoe of which the bearing force is representative of the torque supplied by the brake during operation of the brake motor. The main piston controls the pressure admitted to the brake motor by a cut-off valve responsive to displacement of the main piston and by a variable volume decompression chamber of which a movable wall decompresses the fluid contained in the brake motor when the torque generated by the brake exceeds the limit of a predetermined torque-pressure law.

Abstract: An hydraulic actuator comprises a first piston and a second piston both working in a bore in a housing and the actuator incorporates a pressure proportioning valve. The valve comprises a valve head for engagement with a seating, first and second stems projecting from the head and through the first piston in each of two opposite directions, each stem being of an area smaller than that of the head, a seal between the first stem and the first piston, a first spring acting between an abutment adjacent to the seal and a shoulder on the first stem to urge the head in a first direction away from the seating and into engagement with a stop, and a second spring acting on an enlargement on the second stem also to urge the head in the first direction and to augment the force in the first spring. The second piston is provided with a longitudinally extending recess into which the second stem and the second spring both project.

Abstract: A hydraulic wheel cylinder assembly is particularly for use in a drum brake of the kind in which the wheel cylinder assembly is interposed between one pair or adjacent ends of a pair of brake shoes and a mechanical expander and fixed abutment is interposed between the other pair of adjacent ends of the shoes. The wheel cylinder assembly incorporates a pair of piston assemblies each including an adjustable variable length tappet assembly comprising rotatable and un-rotatable screw-threaded components. The rotatable screw-threaded component can move axially relative to the driven member of a one-way drive mechanism by compression of a spring when a flange on the driven member strikes the wheel cylinder body. This provides a self-centering force which prevents drag when the brake is installed with the shoes one above the other.

Abstract: A brake pressure regulating valve inserted inside the pressure chamber of a wheel brake cylinder of a vehicle comprises a differential or stepped piston having its smaller diameter section slidably supported in a bore of a wheel brake cylinder piston and its larger diameter section guided in the bore of a housing for the wheel brake cylinder. The larger diameter section of the stepped piston has an internal bore between an inlet chamber and an outlet chamber. A regulating valve controlling the inlet of the internal bore is provided by a sealing ring resting against a surface of the larger diameter section of the stepped piston adjacent the inlet chamber and an adjacent end of the wheel brake cylinder piston.

Abstract: A drum brake (10) includes a light-weight backing plate (12) which carries a pair of brake shoes (44, 46). The backing plate comprises a pair of stamped plates (18,20) having a plurality of radially extending arms (22-28) which cooperate to guide the brake shoes. A hydraulic actuator (68) is carried by the brake shoes to move the shoes into engagement with a brake drum (66). A light-weight dust shield (82) cooperates with the brake drum to inhibit the entry of dirt into the brake. The actuator (68) carries a parking lever (94) and cooperates with the lever to effect a parking brake application responsive to pivoting of the lever. An adjustable strut (62) spaces apart the brake shoes. An automatic adjusting mechanism (106) cooperates with the strut to maintain a substantially constant running clearance between the brake shoes and the brake drum.

Abstract: An internal shoe-drum brake is disclosed in which a pair of arcuate shoes can be applied to a rotatable drum by an hydraulic actuation system for normal service braking when the brake acts as a brake of the "two-leading" shoe type and a mechanical actuation system for parking or emergency braking when the brake acts as a brake of the "duo-servo" type. The hydraulic system comprises two hydraulic pistons, each of which acts on the leading end of a respective shoe, and first and second abutments are provided against which the trailing ends of the shoes are adapted to rest. One abutment is fixed but the other abutment includes an auxiliary hydraulic piston which is adapted to be urged against a fixed stop by hydraulic pressure applied to the pistons. The reaction from the trailing end of a respective shoe tends to urge the piston away from the stop, but the area of the piston is sufficient to prevent this happening when the hydraulic pressure is acting on the piston.

Abstract: A wheel cylinder and torque plate construction is provided for a drum brake. The wheel cylinder comprises a molded plastic cylindrical member in a steel shell. The steel shell can be part of a torque plate which can be stamped in two parts which are substantially identical and then affixed together. The torque plate parts have semicylindrical shells which form the wheel cylinder shell when the parts are assembled. The plastic cylinder can be molded in the shell in a suitable die or mold in a plastic molding machine.

Abstract: A drum brake assembly includes a wheel cylinder (36) and extendible assembly (60) disposed between adjoining ends of a pair of brake shoes. The wheel cylinder includes a pair of pistons (40,42) which are in abutting relation with each other and with the extendible assembly to substantially define a non-braking position for the pair of brake shoes. The extendible assembly is operable to move the pair of pistons within the wheel cylinder in response to an excessive clearance between the pair of brake shoes and a rotating drum.

Abstract: A wheel cylinder comprises a bore closed by two pistons which define a pressure chamber therebetween. The pressure chamber is divided into two compartments by a partition member placed in the bore and which comprises a passage communicating the two compartments. One of the compartments is connected to a source of pressurized fluid and a control valve is mounted in the passage for controlling the pressure in the other compartment as a function of the pressure in the one compartment, whereby the wheel cylinder acts as a proportioning valve.

Abstract: A brake assembly includes a backing plate, a pair of brake shoes slidably mounted on the backing plate, and a wheel cylinder supported on the backing plate between contiguous ends of the shoes. A retaining clip attaches the wheel cylinder to the backing plate. The retaining clip includes a base and a pair of opposed tabs extending from the base. One portion of each tab resiliently and releasably attaches the clip to the backing plate. Another portion of each tab projects into a recess in the wheel cylinder to resiliently and releasably retain the wheel cylinder in a mounted position on the backing plate. The clip and the wheel cylinder are capable of being attached to the backing plate from the same side of the backing plate.

Abstract: A drum brake includes a wheel cylinder which cooperates with a pair of brake shoes to urge the latter to a braking position. In order to attach the wheel cylinder to a backing plate, a flange is disposed in abutment with the backplate and the wheel cylinder and a nut cooperates with the flange and the wheel cylinder to prevent separation between the wheel cylinder and the backing plate. Moreover, the nut and flange include openings for receiving a fitting communicating with the wheel cylinder. The nut extends through the flange opening to engage the wheel cylinder and the nut opening is dimensioned to receive the fitting in spaced relation thereto.

Abstract: A drum brake assembly includes a torque member which supports a hydraulic actuator. The hydraulic actuator is engageable with a pair of brake shoes and is operable to move the pair of brake shoes into a braking position. The torque member comprises a central portion which attaches to an axle assembly and a plurality of arms extending radially outward from the central portion. In the preferred embodiment the plurality of arms cooperate with the central portion to substantially form a Y-shaped member. One of the arms substantially forms the hydraulic actuator to integrally form the latter with the one arm. The other arms are provided with slots to direct the movement of the pair of brake shoes and a resilient spring within the slots opposes axial movement of the pair of brake shoes.

Abstract: A drum brake assembly provides a pair of brake shoes which are movable by a hydraulic actuator to a braking position. The hydraulic actuator is carried by a backing plate and the pair of brake shoes is movable relative to the backing plate. A piston is slidably mounted within a bore on the hydraulic actuator and pressurized fluid communicated to the bore acts against the piston to move the piston and pair of brake shoes. A partition is also disposed within the bore to substantially define a secondary chamber which receives pressurized fluid from the bore. The partition is movably disposed within the bore and resiliently engaged with the piston so that increased pressure within the bore is transmitted to the piston via the partition and the resilient engagement. Moreover, the partition controls venting of the secondary chamber so that upon contact of the pair of brake shoes with a drum, backlash or retraction of the pair of brake shoes is limited.

Abstract: A wheel brake assembly in which the webs of brake shoes are held in a planar alignment between and supported by a pair of parallel-spaced interconnected supporting plates, in turn supported by an axle or spindle. A pair of brake contracting springs interconnect the brake shoes, and these springs are positioned with one spring being against the outer surface of each plate. An inner edge of each of the plates is circular and independently adapted to attach to an axle housing, whereby the brake assembly may be readily welded to an axle housing.

Abstract: A wheel cylinder body is made from a constant cross section extrusion having a bore forming the working chamber of the wheel cylinder without further finishing of the chamber wall. A block-like step section, formed as part of the extrusion on the outside of the cylinder portion, is drilled and threaded for appropriate inlet and bleeder screw connections, and mounting holes. The inlet and bleeder screw holes intersect the bore so that they do not engage the sealing cups of the wheel cylinder pistons during wheel cylinder operation.

Abstract: A wheel cylinder piston made of powdered metal is provided with a through hole and a steel or powdered metal insert of hard metal received in and fills the hole. The hardened insert acts directly against a tang of the brake shoe, eliminating the need for reaction pins. The piston of the assembly is made in a die set having a through rod to define the hole, the piston green preform being sintered and sized before or after the insert is in place.

Abstract: Integrally formed brake shoe for use with cylindrical automotive brake drums in hydraulic brake systems are fabricated by bending and shaping sections of extruded lengths of the material having a T-shaped cross-sectional configuration. Connector pins for transmitting brake actuating forces between the hydraulic cylinder pistons and the brake shoes are concavely rounded at their piston abutting ends, and either concavely or convexly rounded at their brake shoe abutting ends, for face-to-face sliding contact with complemental abutting surface portions, respectively, of the hydraulic pistons and brake shoes.