Abstract: A torque-amplifying hydraulic servo-mechanism of the kind including a rotary hydraulic motor and a hydraulic distributor, said motor being of the sliding vane type and the distributor of the "face", open center type. According to the invention, the rotor (50) of the hydraulic motor includes two diametrically opposite cylindrical surfaces (90) in contact with the stator bore and each extending over an arc equal to that between two adjacent vanes (24), and two interconnecting portions each having two flat faces (106, 108) interconnected by a cylindrical surface portion (104); and the number of vanes (94) is advantageously four times the number of said surfaces ( 90), that is eight. The servo-mechanism thus designed may be advantageously used in power steering systems for motor vehicles, and produces an output torque substantially constant irrespective of the relative position of the rotor and stator of the hydraulic motor.

Abstract: A drum brake comprising a pair of brake shoes having adjacent ends engaged by a wheel cylinder and supported against a fulcrum block, respectively, is disclosed. A handbrake lever, pivoted on one of said shoes in the vicinity of the wheel cylinder, is capable of cooperating with a spacer located between the shoes in the vicinity of the wheel cylinder to urge the shoes toward a rotary drum. An automatic brake adjuster is provided between the spacer and the other of said shoes, and the handbrake lever engages the one shoe by means of a detachable abutment adapted to permit removal of the drum without resetting of the adjuster. The one shoe and the handbrake lever are received in a notch provided at one end of the spacer, and a substantially rectangular leaf spring is located between the lever and the adjacent edge of the notch to urge the lever against the one shoe in a direction substantially parallel to the drum axis.

Abstract: A disc brake comprising a caliper straddling a rotary disc and carrying a pair of friction pads is disclosed. The friction pads are slidably received and anchor on guides defined by the circumferentially spaced edges of a radial aperture in the caliper. The caliper is slidably mounted on a fixed support member and carries a fluid pressure motor comprising a piston received in a cylinder and capable to occupy an idle position, an operating position closer to the disc than the idle position and a retracted position further from the disc than the idle position. Slots are provided in the guides to permit removal of the pads when the piston occupies its retracted position, and a detachable resilient clip is normally mounted on an axially extending portion of the cylinder between said cylinder and the adjacent pad to prevent the latter from moving back opposite the corresponding slot whatever the position occupied by the piston.

Abstract: A disc brake including a hydraulic actuator and a mechanical actuator is disclosed. The hydraulic actuator comprises a piston and the mechanical actuator comprises a push rod adapted to engage said piston through a self adjusting device, said adjusting device including a nut received on a threaded rod associated to said push rod, a thrust bearing capable to rotate said nut relative to said push rod on movement of said piston in a brake applying direction, and a clutch spring adapted to prevent rotation of the nut in the opposite direction. The thrust bearing comprises a cage which cooperates with the piston through a circumferential lost-motion connection adapted to limit rotation of said nut relative to said threaded rod to a predetermined angle on each hydraulic brake application.

Abstract: An electronic antiskid control device which comprises a frequency multiplier of the phase locked-loop type, which receives repetitive pulses of predetermined frequency representing the speed of one wheel. The phase locked-loop multiplier normally outputs a second pulse signal, the frequency of which is normally equal to the frequency of the wheel speed signal multiplied by a given number. A digital counter which is periodically reset at a frequency equal to that of the wheel speed signal measures the number of pulses of the second pulse signal during each period. The measured number is transfered into a memory element and calculating apparatus responsive to the value stored in the memory element control an antiskid cycle. In operation under normal conditions, the number stored in the memory element is constant and has no action on the calculating apparatus.

Abstract: An accumulator charging valve has a housing with an inlet and two outlet orifices respectively connected to the pump outlet, to a fluid accumulator and to an open center hydraulic circuit. A main passage is provided between the inlet orifice and the second outlet orifice, with a movable valve member mounted in the main passage, and operated by a differential piston having a face of smaller diameter exposed to the pressure prevailing at the inlet orifice and a face of larger diameter projecting into a control chamber, forming a resilient variable volume enclosure. A leakage passage is provided between the inlet orifice and a low pressure reservoir and has a first portion with an orifice of restricted cross-section situated between the inlet orifice and control chamber, and a second portion also with an orifice of restricted cross-section situated between the control chamber and the reservoir.

Abstract: A hydraulic amplifier comprising a housing wherein is defined a pressure chamber. A servo piston is slidable in a bore opening onto the pressure chamber. The amplifier also comprises a set of control valve connectible to a high pressure fluid source and a low pressure reservoir. An operator operated control rod has one end projecting into the chamber. In the pressure chamber is mounted a lever mechanism comprising a lever having one end pivoted on a pin associated with the housing, and the other end is moved by the control rod. The lever mechanism also comprises a rocker member which is pivoted on the lever and whose respective ends can bear on the servo piston and are adapted to move at least one valve in the control valve set. The pin is slidable relative to the housing and is urged by resilient means into an idle position. The control valve set comprises an exhaust valve operated by a rocker member, and a high pressure valve operated in response to the movement of the pin from its idle position.

Abstract: A drum brake which comprises two brake shoes, an actuator situated between two first adjacent ends of the shoes and a fixed fulcrum block situated between the other two ends of the shoes. An adjuster is designed to increase the distance between the first ends of the shoes automatically as a function of the wear on the lining of the shoes. The adjuster comprises a lever pivoted at one end on a first of the shoes in the vicinity of the actuator. A pawl is pivoted on the first shoe and biased by a resilient member into engagement with a toothed sector formed on the other end of the lever. An operating member is responsive to an increase in the distance between the first ends of the shoes, so as to pivot the lever in the direction corresponding to adjustment of the brake. The resilient member comprises a spring of which at least part cooperates with the surface of the lever remote from the first shoe irrespective of the position of the adjuster.

Abstract: A braking correction device of the type having a housing in which is defined a bore with a stepped piston slidably mounted therein so as to divide the bore into an inlet and an outlet chambers respectively communicating with the master cylinder and the brake actuators. The stepped piston has a head with a peripheral groove in which an annular ring is mounted with axial and radial clearance. The ring cooperates with the bore surface to control communication between the inlet and outlet chambers as a function of the position of the stepped piston. The bore surface has a first part forming a fluid tight side wall and a second part forming a side wall of porous material. The second part is adjacent the outlet chamber. A radial clearance is provided between the piston head and the bore surface of porous material for by-passing the sleeve of porous material to ensure the unihibited hydraulic flow between the inlet and outlet chamber is obtained during the non proportioning phase.

Abstract: The invention relates to a hydraulic booster of the closed-center type and comprising a housing containing a working chamber, an actuating piston slidable in the working chamber, a set of a high-pressure valve and an exhaust valve of the ball valve type controlling fluid connections between an accumulator, the working chamber and an exhaust orifice. The high-pressure valve is controlled by a tappet including a sleeve having a central passage therein communicating with the working chamber and the exhaust orifice. The exhaust valve controls the fluid flow through the central passage. Both valves are actuated by movement of a sliding block adapted to engage the exhaust valve member.

Abstract: A disc brake of the type comprising a caliper or frame member slidably and floatingly mounted on a fixed member by way of two guide keys is disclosed. According to the invention, the guide keys slidably cooperate with one of the members by way of guide surfaces and floatingly cooperate with the other member by way of a cylindrical surface cooperating with a substantially plane surface. Preferably, the lines of contact defined between the cylindrical surfaces and the plane surfaces are comprised in a plane substantially parallel to the disc faces and which lies between the faces or offset relative to the latter towards an actuator.

Abstract: The invention relates to a servomotor for assisting the operation of a power brake system. The servomotor includes in a housing a power-assisting part and a part forming a hydraulic master-cylinder. The power-assisting part is adapted in use to be connected to an external power source such as a vacuum source. A valve assembly operated by an operator-operated intake member controls the generation of a pressure differential across a driving piston by allowing air to replace the vacuum on one side of the piston. The master-cylinder part includes an assembly having two coaxial pistons. The first piston is attached to the driving piston of the power assist part whereas the second piston is actuated by the intake member. Both coaxial pistons project into a chamber which is divided by a sealing ring. The central piston is adapted to pass through the sealing ring in response to an input force from the input member to further pressurize the fluid in the outlet portion of the chamber.

Abstract: A control circuit for delivering control signals to interrupt admission of the fuel-air mixture in the low speed and idle circuit of the carburetor of an internal combustion engine. The control circuit is operated according to the engine operating conditions. The control signal is delivered in response to comparison of a signal whose level is representative of the positive or negative variations in the duration of an engine cycle with a substantially periodic signal to generate a pulse shaped signal. The width of the pulses increases when the vehicle is accelerating and decreases when the vehicle is decelerating.

Abstract: A disc brake comprising a caliper carrying a pair of friction pads and including a hydraulic fluid motor which directly applies one of said pads against a corresponding face of a disc and, by reaction through a sliding connection between the caliper and a fixed support, the other pad against the other face of the disc is disclosed. Extraction of the pad adjacent of the fluid motor is possible through a radial aperture in the caliper by moving the pad in front of a recess provided in at least one of circumferentially spaced edges of the aperture, said aperture being offset towards the fluid motor. A removable heat shield is normally inserted between the fluid motor and its adjacent pad to avoid escape of the latter and to avoid boiling of the hydraulic fluid in the fluid motor due to heating of the brake.

Abstract: A power steering mechanism comprises distributing means for communicating fluid pressure to the compartments of a fluid motor associated with the steering linkage of the vehicle. Each distributing means comprises a ball valve member disposed in a chamber of a housing. The valve member is urged towards a first valve seat defined in a low pressure supply passage, by means of spring means, and towards a second valve seat defined in a high pressure supply passage by means of an extension of an actuating piston, said extension extending through the low pressure passage. The piston is moved by way of a sleeve disposed intermediate between the input and output members and connected thereto by means of a spline and screw arrangement. In response to a torque applied to the input member, the sleeve is allowed to move axially for displacing the piston and modifying the position of the valve member, thereby changing the value of the pressure transmitted to the associated compartment.

Abstract: A power steering device has a distribution valve inserted between a high pressure source formed by a pump and a reservoir for creating a pressure difference in a fluid motor connected to the steering linkage, in response to application of a torque to the steering shaft of the vehicle, thereby providing assistance to operation of the steering linkage. A by-pass passage connects the high pressure output from the pump with the reservoir and the cross section of the by-pass passage is controlled as a function of the pressure difference between the chambers of the fluid motor. The means for controlling the cross section of the by-pass passage comprise a slidable piston disposed substantially transverse in the path of the fluid flow. The piston comprises grooves and lands for respectively allowing and interrupting fluid flow in the by-pass passage. The axial position of the piston is a function of the pressure difference.

Abstract: The invention relates to a control valve of a hydraulic booster having an inlet orifice adapted to be connected to a hydraulic pump, an outlet orifice adapted to be connected to an open-center valve, a working orifice connected to the booster pressure chamber and an exhaust orifice connected to the reservoir. The control valve comprises mainly a first and a second valve members respectively controlling fluid connection between the working and the exhaust orifices. The first valve member is secured to a cylinder which partly covers the outlet orifice when this valve member is unseated.

Abstract: A drum brake of the type comprising two brake shoes adapted to be spaced apart by a wheel cylinder. The distance between the ends of the shoes which cooperate with the wheel cylinder is automatically increased to compensate for the wear of the brake linings by an adjusting device which defines the rest position of the ends. The device comprises an extensible member of the screw and nut type, two annular resilient members which grippingly engage corresponding cylindrical portions of the extensible member, and a cam which rotates the resilient members one relative to the other in a first direction upon a brake application and in the opposite direction upon brake release to limit extension of the extensible member to a predetermined value.

Abstract: The braking correcting device of the hydraulic type comprises a housing in which is defined a cavity. A stepped piston is disposed movable in the cavity and has one end which projects outwards from the housing, the piston having a head slidable in a bore formed in the cavity of the housing for separating the cavity into an inlet chamber which adjoins the piston end face having the smaller effective cross sectional area, and an outlet chamber which adjoins the piston end face having the larger effective cross sectional area. The piston head contains a peripheral groove which receives with axial and radial clearance a ring of elastomeric material capable of disconnecting the two chambers when the piston moves a predetermined distance from its idle position which is fixed relative to the housing, overcoming a return force. The bore comprises a first portion having a fluid tight side wall adjoining the inlet chamber, and a second portion contiguous to the first portion and adjoining the outlet chamber.

Abstract: A disc brake comprising a piston mounted in a cylinder associated with a carrying member movable towards a rotary disc from an idle position to urge directly a friction pad towards the corresponding face of the disc is disclosed. The friction pad slidably cooperates with appropriate surfaces defined on two circumferentially spaced edges of an aperture provided in the carrying member, at least one of the edges comprising a slot offset towards the piston relative to the appropriate surfaces to permit radial extraction of the pad when the latter is brought opposite the slot. The piston is adapted to be pushed back away from the disc towards its idle position in opposition to an automatic adjuster associated with the piston to permit radial extraction of the pad by introduction of a tool between the pad and the piston after removal of a wedge forming element normally inserted therebetween.