Abstract: A drum brake assembly having a parking brake actuating lever is so arranged that the parking brake cable end may be assembled in a blind fashion to the end of the actuating lever. The cable is provided with an enlarged end or button. The cable and spring are inserted through a guide tube and pushed inwardly into the brake assembly with the guide tube or a combination of the guide tube and a separate spring guide placing the cable button in alignment so that it is aimed at a funnel-like guide and retention member formed on the end of the parking brake actuating lever. Further axial movement of the parking brake cable and its enlarged end result in a camming action which moves the enlarged end through a one-way snap connection so that the cable is able to apply cable tension forces to the parking brake actuating lever.

Abstract: Braking unit for vehicle, of the type comprising an axial actuating helical spring maintained in release position, against its elastic reaction force, through a screw-nut system rotatively driven by an electric motor, the spring acting upon the brake through the intermediary of a hydraulic master cylinder of which the piston is axially connected to an abutment ring of the spring also mechanically connected, via a screw-nut system to the rotor of an electric motor, such an unit being applied to a spring braking system for a vehicle possibly with a built-in park brake.

Abstract: A drum brake assembly having a parking brake actuating lever is so arranged that the parking brake cable end may be assembled in a blind fashion to the end of the actuating lever. The cable is provided with a button. The lever has a return spring which has one end attached to the lever and the other spring secured to the backing plate about a parking brake cable opening through the backing plate. The spring end attached to the lever has a retaining ramp and a hook end, the retaining ramp being above an open channel formed on the lever end and the hook end being secured to the lever one end above the channel. The cable button is inserted axially through the backing plate opening provided for the cable and through the spring, being guided by that spring, to a point above the channel open receiving end.

Abstract: A parking brake assembly of the blind-cable-connection type including a backing plate containing an opening, a helical guide spring arranged to guide a flexible resilient inner cable member toward a ramp surface on a parking brake lever for the blind connection to the inner cable member to the lever, characterized in that the angle of inclination of the ramp surface relative to the cable axis is contained in a plane that is both parallel with the longitudinal axis of the lever and that is inclined at an acute angle relative to the axis of the inner cable member. This construction permits the parking brake lever to be simply and economically formed from a blank of flat metal stock, the cable-retaining slot being defined by a slot contained between bifurcated portions of the ramp surface. The helical guide spring includes portions having tightly wound turns, thereby to assist in connecting the spring with the backing plate and/or with the parking brake lever.

Abstract: A generally hat-shaped disc for a disc brake system is provided with an inner cylindrical surface serving as the drum of a drum in hat parking brake. A unitary backing plate supports the parking brake assembly and provides integral mounting parts for the fist type sliding caliper of the disc brake assembly.

Abstract: A disc brake includes two pad supporting levers which are pivotally mounted on a single pivot. One of the levers has a first adjustment bolt which abuts the other lever to control the maximum clearance between the pads and a second which abuts the bracket on which the levers are pivotally mounted to control the clearance between one of the pads and the rotatable disc. A linkage which interconnects the levers induces same to rotate and clamp the pads against the rotatable disc by (a) a foot pedal controlled hydraulic servo integrated with the bracket and/or (b) a cable arrangement operatively connected with a hand brake.

Abstract: The present invention relates to disc brakes suitable for use on commercial vehicles, the disc brake incorporating a parking brake facility in addition to a service brake facility. The disc brake of the present invention comprises a housing within which a brake actuator is arranged, the parking brake facility being operable by a lever connected to a cam member which is eccentrically supported on a pivot pin carried by the housing. The cam member is arranged to act on the brake actuator arrangement as the lever is moved, the lever projecting laterally of the cam member, near to the axial mid region of the cam member.

Abstract: A tandem parking brake caliper system for use with the rotor of a disc brake of a wheel of an automotive vehicle. The system includes a caliper adapted to be slidably mounted in a boss of an anchor extension mounted to a non-rotating portion of the vehicle. The caliper surrounds a radially outer peripheral portion of the rotor on opposite sides thereof. Frictional brake linings are mounted on the caliper surfaces which face the rotor. A movable piston is mounted in a bore of the caliper for engaging one of the linings for forcing the linings into engagement with the rotor upon the application of force onto the piston and the resulting translation of the caliper. An actuating lever is rotatably mounted to the assembly and includes a cam surface for engaging and applying translating force to a cam follower surface of the piston. The lever is connected to a cable actuating the lever.

Abstract: A wheel disc brake system for a motor vehicle connected to a brake fluid pressure system that includes a pressure relief apparatus for moving the inner piston of the wheel brake back into the brake housing piston chamber by an Allen wrench insert into an axial tool hole at the front face of the inner piston accessed through the axial oil hole of the outer piston. Rotation of the wrench rotates the inner piston along the actuating screw member in the brake housing and so moves the inner piston away from the outer piston so that the outer piston can be easily pushed into the brake housing and new brake pads mounted to the calipers. Reverse rotation of the wrench pulls the inner and outer pistons back into operational position. The invention also includes a cylindrical nose extending from the inner piston having at least one seal to defend the tapered actuating areas of the inner and outer pistons from contamination through the oil hole of the outer piston.

Abstract: A self-energizing disc brake of the spreading type is applied by a pair of oppositely acting hydraulic pistons which work in a common bore in the housing of the brake. One piston acts directly on an adjacent lug on a pressure plate and the other piston acts on a lug on a pressure plate through a transmission member which extends through the piston and may be coupled at its outer end to a hand-brake or similar lever.

Abstract: A brake system for a motor vehicle having three sources of communicating pressurized fluid to wheel brakes and having a mechanical brake. Two of the sources of communicating pressurized fluid are the reservoirs of a dual master cylinder and provide first and second hydraulic brake subsystems. The remaining source is an emergency master cylinder and provides a third hydraulic brake subsystem. The mechanical brake and the third hydraulic brake subsystem are operatively connected to an emergency brake pedal. Disc brakes each have a pair of floating calipers, each caliper being in fluid communication with a pair of sources of communicating pressurized fluid. Drum brakes have at least one dual chambered wheel cylinder in fluid communication with two sources of communicating pressurized fluid. The first and second hydraulic brake systems, as well as the emergency brake pedal, operate brakes on each of the four wheels of a motor vehicle.

Abstract: A parking brake assembly comprising a pair of brake shoes pivotally mounted on a backing plate, a brake operating lever pivoted to the brake shoe and operable by a remote cable for pivoting the brake shoes against a brake drum, and a coil spring provided under compression between the brake lever and the backing plate. During shipment of the parking brake assembly, it is attached to an axle and the coil spring has an end that extends to an opening in the back plate. The cable including a conduit and an inner member, preferably a flexible strand, is handled separately. After the parking brake assembly is attached to an automotive vehicle, the cable can be connected even though the brake drum is in place and prevents seeing the interior of the brake assembly. Specifically, the strand is then forced through the conduit and the coil.

Abstract: A disc brake for service combined with parking operation is provided which includes a cylinder component, a shaft to be braked, a stator impossible to rotate relative to the cylinder component but possible to move axially relative to the shaft, a friction disc impossible to rotate relative to the shaft but possible to move axially relative to the shaft, a piston slidably engaged to the cylinder component and allowing the stator to frictionally engage the friction disc by a fluid pressure, a plate located at an end of the piston on the side opposed to the side facing the stator and the friction disc, the plate being rotatable by an exterior force, and a ball ramp mechanism provided between the piston and the plate.

Abstract: In order to overcome the disadvantage of overspinning of a winch drum when a disconnect device adjacent the drum is disengaged, a drag brake apparatus is provided for limitedly restricting the rotation of the drum when an actuator having a braking element is continually urged against the drum by a spring. A control mechanism includes a control lever assembly movable to operate a hydraulic valve assembly for the primary control of the winch drum, and movable to operate an associated valve for controllably directing pressurized fluid to the actuator for supplementing the spring force. Thus, a first drag brake mode can be attained for substantially freespool operation of the drum, and a second drag brake mode can be attained for controlled load dropping operation of the drum.

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 mechanical emergency and parking brake system, for vehicles of the type having a power steering pump, includes a check valve having an input port coupled to the pump outlet and an output port coupled to hydraulically deactuated spring brakes through brake lines. A pilot check valve has its inlet port coupled to the input port of the check valve and an output or return port coupled to the power steering gear. The pilot port of the pilot check valve is coupled to the output port of the check valve so that the pilot check valve opens only when the pressure at the output port of the check valve is above a chosen pressure. This allows hydraulic fluid to flow from the pump, through the pilot check valve, through the power steering gear and to the reservoir. To reapply the brakes, the operator actuates a valve which disconnects the brake ports from the output port of the check valve and connects the brake lines to the reservoir.

Abstract: A brake actuating mechanism includes a housing defining a cylinder and a tubular piston, slidingly sealed within the cylinder. A pull-rod passes through the piston and is provided at one end with member for connection to a brake linkage mechanism. The other end of pull-rod is provided with abutment member which engages one end of a guide spool, the other end of the guide spool engaging the end of the piston. A pivot member is provided between the guide spool and the piston to permit rocking of the guide spool and pull-rod relative to the piston. A lever mechanism may act on the guide spool to provide for mechanical actuation of the brake.

Abstract: A parking brake mechanism in a disc brake includes a bottomed tubular adjusting nut slidably fitted in a bore defined in a cylinder bottom coaxially with a piston with a seal ring interposed and having a closed end projecting into the cylinder and coupled to piston, an adjusting bolt axially movably threaded in the adjusting nut and having a head projecting out of the cylinder, a first spring interposed between the head and the cylinder bottom for normally urging the adjusting bolt in a direction out of the cylinder, a thrust bearing interposed between the head and the first spring for ensuring smooth rotation of the adjusting bolt, a pusher disposed coaxially with the adjusting bolt and having in one end a slot substantially perpendicular to an axis of the adjusting bolt, the pusher serving as a clutch for selective engagement with the head, a second spring for normally urging the pusher in a direction out of the cylinder, a plate having an intermediate portion extending through the slot and interposed betwe

Abstract: A rail vehicle brake unit having a tubular housing and a slack adjuster movable therein in a brake force applying direction in response to a braking force applied to a push rod has a simple parking brake attachment. Thus, a sleeve abutting the slack adjuster presents a movable shoulder, which in turn is coupled with a pivoted parking brake lever for movement thereby to actuate the brakes.

Abstract: A cross-drive transmission has a hydraulic brake apply system and a mechanical brake apply system actuated through the same rotary input shaft of the vehicle operator. Rotation of the input shaft rotates a cam which controls a brake control valve which causes a regulated brake apply pressure to be delivered to the hydraulic portion of the brake system for service brake actuation. The cam is moved angularly through a desired angular range which will normally deliver the maximum hydraulic pressure used to actuate the brakes. After the angle is achieved, further rotation of the input shaft causes the cam to enter a dwell phase which permits additional stroke of the mechanical brake apply system if required. This may be required at times because of inadequate hydraulic pressure available from a suitable hydraulic pressure source or the inability of the hydraulic brake apply system to achieve the required braking effort.

Abstract: A self-energizing disc brake of the spreading type is provided with an actuator unit incorporating an hydraulically-operable mechanism and a mechanically-operable mechanism. The unit comprises a member which is detachably secured to the housing of the brake and provides a mounting for both mechanisms which extend into the housing through a common opening. The hydraulically-operable mechanism comprises a cylinder in which work opposed pistons acting to separate lugs on the pressure plates and the mechanically-operable mechanism may take any convenient form. The cylinder is tangentially arranged with respect to the plates.

Abstract: A disc brake assembly includes a caliper member, a piston axially slidably disposed within a cylinder body of the caliper member to be actuated by hydraulic fluid under pressure, and a parking brake mechanism assembled within the cylinder body to actuate the piston in its operation.

Abstract: An internal shoe-drum brake includes a first actuator disposed between one pair of adjacent brake shoe ends, a strut extending between the shoes adjacent the actuator, an abutment device disposed between the other pair of adjacent shoe ends, and a mechanical second actuator. Lever arms are pivotally engaged with the strut at spaced locations and are operatively associated with the second actuator. Rollers carried by the lever arms engage the brake shoes at intermediate locations lengthwise thereof so that actuating forces from the second actuator are applied to the shoes at said intermediate locations to initiate duo-servo operation of the brake.

Abstract: An adjustment device for a brake actuator including a spindle (20) is arranged between an hydraulically movable piston (12) and a mechanically movable tappet (18). The spindle (20) is formed at its outside with left- and right-hand threads (26) and (28), respectively, on which a collet (22) and an adjusting nut (24), respectively, are threaded in non-self-locking manner or, in other words, reversibly. The collet (22) and the adjusting nut (24) form a conical coupling (25) which, when engaged or closed prevents rotation of the structural members so that the adjustment device acts as a rigid member between the tappet (18) and the piston (12).

Abstract: An actuating apparatus is provided for use in a disc brake. The disc brake includes a brake piston slidably accommodated in a brake cylinder. A mechanically actuatable brake lever is non-rotatably coupled to an actuating shaft. The actuating shaft is rotatably accommodated in a bore in a brake cylinder housing. A thrust member is positioned between the actuating shaft and the piston or a further actuating element. A spring preloads the brake lever in the direction of rotation toward a final position. To create an actuating apparatus easy to set-up and mount, the spring also urges the actuating shaft in an axial direction against a stop or a support.

Abstract: The disc brake (10) includes a parking cartridge device (28) which transfers reaction forces of the mechanical parking actuator (36) directly to the caliper housing (12) and also provides support and guidance for a cable (90) attached to lever arms (70) of the mechanical parking actuator (36). The mechanical parking actuator (36) is disposed within an opening (34) of the parking cartridge housing (30), the parking cartridge housing (30) having a plurality of through openings (42) so that bolts (50) may be secured at one end to the caliper housing (12) and at the other end to a bracket (60) which abuts an end (33) of the parking cartridge housing (30).

Abstract: A disc brake assembly includes a caliper cooperating with a pair of friction pads to oppose rotation of a rotor. The caliper defines a bore receiving a piston assembly and a cartridge assembly. The cartridge assembly carries an actuator which is movable during a parking brake application.

Abstract: The block brake unit for rail vehicles has a service brake which includes a transmission lever which is pivoted by a brake piston to shift an actuating rod coupled with a brake block carrier. A parking brake includes a spring-loaded cylinder which is coupled by a pivotable parking brake lever through a transmission lever to the actuating rod. An impact wedge coupling comprising a roller and wedge surface is provided between the parking brake lever and the transmission lever. By a suitable choice of the inclination and shape of the wedge surface, the transmission ratio for the parking brake can be readily adjusted for requirements in particular situations without the necessity for changes of the exterior dimensions or mounts and without any changes of the transmission ratio for the service brake. The wedge surface can also be constructed to provide a constant progressive or decreasing transmission ratio and also a fast application for the parking brake.

Abstract: An automatic adjusting device for a hydraulically and mechanically actuatable disc brake is disclosed including an adjusting member interposed between a brake piston and a mechanical actuating device. The adjusting member includes an adjusting nut connected to the brake piston by a non-self locking threaded element and includes a conical friction surface cooperating with a friction surface on a hand brake piston. A stop on an axially adjustable sleeve supports the adjusting nut and provides for adjustment of the spacing between the friction surfaces in the inactuated position.

Abstract: A disc brake assembly is provided with a plate which cooperates with a pair of pistons to prevent rotation of one of the pistons relative to the caliper. The plate is further designed to act as a heat shield for a boot assembly associated with the piston.

Abstract: A disc brake has a hydraulic parking brake actuator. A parking brake piston is advanced upon actuation to close a parking brake valve, sealing hydraulic fluid in the service pressure actuating chamber. Further advancing movement of the parking brake piston generates hydraulic pressure in the actuating chamber and engages the brake. Increased pressure in the actuating chamber also increases the sealing force on the valve controlling the sealing of the pressure chamber. The parking brake mode may also be obtained while hydraulic service brake pressure exists in the actuating chamber by moving the parking brake piston sufficiently to close the parking brake valve, trapping pressurized hydraulic fluid in the actuating chamber and holding the brake in the actuated condition. This pressure may be further increased, if desirable, by further advancing movement of the parking brake piston to further increase the pressure.

Abstract: An annular multi-piston brake apparatus (8) for selective holding engagement against a rotatable element (34). The annular multi-piston brake apparatus (8) advantageously includes first and second brake pistons (40,46) radially overlapping to allow the pistons to individually contact the rotatable element and stop rotation. Compact packaging of the brake apparatus is featured.

Abstract: A service brake pedal is overlapped by a parking brake pedal with both pedal arms mounted on a common axis for pivotal apply and release movements. The service brake pedal arm contacts a pin holding the push rod for the master cylinder, applying the hydraulic service brakes when the pedal is depressed. When the transmission lever is shifted into the park position a solenoid type servo is energized, engaging a pawl, mounted on the parking brake pedal arm, with a gear sector pivoted about the pivot point of the brake pedal arms. A one-way spring clutch is energized to hold the link in which the push rod pin is installed in the applied position during parking brake apply, retaining hydraulic brake pressure during that operation. When shifting to park, the parking brake pedal arm is raised by a vacuum servo so that the parking brake pedal can be actuated to apply the parking brake without contacting the service brake pedal, and therefore without hydraulic pressure resistance.

Abstract: A disc brake, particularly suitable for use in tractors and like vehicles, is disclosed. Balls are located in complementary inclined recesses in a pressure plate and in an adjacent end wall of the brake housing. The brake is actuated by radial movement of the pressure plate, which produces a camming effect as the balls tend to ride out of the recesses, so that the pressure plate moves axially to urge a rotatable friction disc into engagement with a surface of the housing. Pilot pins engage with lugs on the pressure plate, constraining it against angular movement, so that when on application of the brake the pressure plate engages the friction disc, the pressure plate is prevented from being carried round with the friction disc, ensuring that no servo effect takes place.

Abstract: In a spreading disc brake, actuating movement of an actuator assembly in a stationary housing can be effected hydraulically by a piston working in a cylinder and acting on a pull-rod through a rocking thrust coupling, and the pull-rod is adapted for connection to a hand-lever in order to apply the brake manually or mechanically. The thrust coupling is provided at an intermediate point in the length of a lever, a first pivotal connection is provided between the pull-rod and an intermediate point in the length of the lever, a second pivotal connection is provided between one end of the lever and the housing, and a third pivotal connection is provided between the opposite end of the lever and a transmission member for connection to the hand-lever.

Abstract: A mechanical actuator for a disc brake assembly comprises a cam shaft and a pair of toggles. The cam shaft is designed with different interfaces for the pair of toggles to minimize travel for the cam shaft and maximize clamping forces during a parking brake application for the disc brake assembly.

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: In a disc brake the application of the brake is initiated by angular movement of at least one pressure plate with respect to a reaction member to cause the pressure plate to move axially into engagement with a friction disc which, in turn, is urged into engagement with a surface in a stationary housing. The angular movement is effected hydraulically by an actuator comprising a piston working in a bore of a cylinder, the axis of which is substantially at right angles to that of the brake. The piston acts through a part-spherical rocking thrust coupling associated with a pull-rod passing through the actuator with a substantial clearance, the inner end of the pull-rod being pivotally coupled to a lug on the pressure plate, and the outer end being adapted for connection to a hand lever by which the pull-rod can be moved in a brake-applying direction.

Abstract: A disk brake operating mechanism including an hydraulically operated piston in a cylinder arranged to move a friction pad into contact with a disc, in which a mechanically actuated brake operating mechanism is provided, the mechanism consisting of a piston rod abutting the piston and being axially movable in relation to it. An actuating collar is arranged around the piston rod at a position outside the piston and is supported at a part of its circumference against movement towards the cylinder by a stop. A strut or other device is provided to enable an actuating force to be applied to the part of the collar diametrically opposite the stop to cause it to lock onto the piston rod and move the piston rod to effect application of the pad to the disk.

Abstract: A pressure actuated disc brake has a mechanical arrangement for actuating the disc brake for parking. It has a coil spring clutch mechanism, or a sprag clutch mechanism, acting on a sleeve nut, which is threaded on a piston shaft. A drive arrangement causes the clutch mechanism to grip the sleeve nut and rotate the nut to move the shaft and piston to mechanically actuate the brake.

Abstract: A brake pedal contacts a pin holding the push rod for the master cylinder, applying the hydraulic service brakes in the normal manner when the pedal is depressed. When the transmission lever is shifted into the park position a solenoid type servo is energized, engaging a pawl, mounted on the brake pedal, with a gear sector pivoted about the pivot point of the brake pedal. A one-way spring clutch is energized to hold the link in which the push rod pin is installed in the applied position during parking brake apply, retaining hydraulic brake pressure during that operation. When shifting to park, the brake pedal is raised by a vacuum servo so that the pedal can be actuated to apply the parking brake without contacting the push rod pin, and therefore without hydraulic pressure resistance. Movement of the pedal with the pawl engaged exerts tension on the parking brake cable through the gear sector to apply to parking the brake.

Abstract: A brake system for a vehicle in which a pair of brake discs are mounted on two opposed shafts in alignment with one another and pucks are disposed on opposite sides of each of said discs. The pucks between the discs are supported by relatively movable support members, and an adjustment device is disposed between the support members to vary the spacing between the pucks and discs to compensate for wear occurring in the pucks from braking operations. The brakes are operated by a hydraulic actuator which presses the pucks onto the respective discs and urges them toward an abutment, the abutment being either a fixed member or the head of a mechanical brake which can apply a braking force in the direction opposite to the hydraulic actuator, to apply the brakes.

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 mechanical parking brake mechanism which comprises firstly a sector pulley pivoted on the backing plate of a brake drum to guide an intermediate portion of a parking brake wire and formed at its guide face with at least two radial recesses spaced from each other at a predetermined interval and secondly a parking brake wire integrally provided at its intermediate portion with at least two projections to be selectively engaged with the respective recesses of the sector pulley in accordance with the length of pulling stroke of the parking brake wire, thereby to avoid undesired excessive force acting on the parking brake wire and to enhance transfer efficiency in the input force applied to the parking lever of the mechanism.

Abstract: A brake system for a vehicle having front wheel drive includes a parking brake assembly (58, 60) comprising a band brake which is engageable with an existing universal joint (62, 64). The parking brake is independent from a pair of front brake assemblies 30 and a pair of rear brake assemblies 34. Each band brake is independently operated via cables (44, 46) so that failure of one band or cable does not affect the parking brake operation for the other band or cable.

Abstract: A shoe drum brake of the type including a pair of shoes, a first having a cylindrical portion, a second strut having external screw thread portion telescopically received in the cylindrical portion, an adjusting nut threadingly engaging with the screw thread portion of the second strut and abutting with the first strut, and an automatic shoe clearance adjusting mechanism associated with a hand brake lever, the mechanism comprises a supporting shaft pivotally connecting the hand brake lever with one end of either of the first and second struts, and an adjust lever for rotating the adjusting nut in association with the movement of the hand brake lever. A spring is provided to bias the automatic shoe clearance adjusting mechanism toward a backing plate.

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: In a disc brake the application of the brake is initiated by angular movement of pressure plates in opposite directions, the pressure plates then moving apart into engagement with friction discs which are urged into engagement with opposed radial surfaces in a stationary housing. The angular movement is effected hydraulically by an actuator comprising a piston working in a bore of a cylinder, the axis of which is substantially at right angles to that of the brake. The piston acts through a part-spherical rocking thrust coupling associated with a pull-rod passing through the actuator with a substantial clearance, the inner end of the pull-rod being pivotally coupled to the junction of a pair of toggle links connected between lugs on the pressure plates. The outer end of the pull-rod is extended for connection through a transmission member to a hand lever for applying the brake mechanically.

Abstract: In a brake actuator device having a fluid pressure actuated service brake and a spring-applied, fluid pressure released auxiliary brake that cooperates with the service brake via a friction clutch mechanism, there is provided a manual release mechanism for releasing the spring-applied brake in the absence of fluid pressure. The manual release mechanism operates to relieve the tension of the actuating spring by causing the piston through which the spring operates to engage a stop formed on the casing of the brake actuator device, so that the spring is caged at its opposite ends by the casing of the brake actuator device. Extension of a retracting screw to initiate the manual release operation is automatically retracted following engagement of the spring piston with its stop to reset the manual release mechanism in readiness for a subsequent operation.

Abstract: A duo servo drum brake includes a pair of brake shoes which are movable by a hydraulic actuator during a service brake application to a braking position in engagement with a rotatable member. A strut and parking lever are engageable with respective brake shoes to separate the same during a parking brake application. In order to control a running clearance between the pair of brake shoes and the rotatable member, an extendible assembly is disposed between the pair of brake shoes opposite the hydraulic actuator. The extendible assembly is also responsive to a parking brake application to expand the pair of brake shoes into engagement with the rotatable member.