Abstract: The master cylinder (10) comprises a seal cup (24) made from an elastomeric material assembled with axial and radial play around the head (18) of the piston (16). A stop ring (40) slidably received in the bore (14) permits to unseat the seal cup (24) from the shoulder (30) of the piston in order to connect the supply chamber (28) and the pressure chamber (26). When the piston (18) is displaced towards the latter, it displaces the stop ring (40) by the cooperation of two conical surfaces (54 and 56), the seal cup (24) being supported on a flat surface, composed of the radial shoulder (30) of the piston and the radial face 42 of the stop ring (40) substantially continuous.

Abstract: A safety valve for isolating a portion of a service conduit from a vacuum generator should a leak occur in that portion of the service circuit. The safety valve has a housing with a chamber therein. The chamber has an inlet port connected to the service circuit and an outlet port connected to the vacuum generator. A wall member located in the chamber is biased by a spring toward a first position whereby the vacuum generator is connected to the service circuit. Should a leak occur in the service circuit, air flow through the chamber acts on the wall to overcome the resistance of the spring and moves the wall to a second position to seal the chamber and thereby interrupts air flow through the chamber to the vacuum generator.

Abstract: The invention relates to a two-compartment reservoir for liquid, comprised of two superposed parts and provided with a transfer channel which opens into both compartments and which runs parallel to the plane of the liquid contained in the reservoir.The junction plane of the two parts of the reservoir is inclined, with respect to the bottom of each of them, at an angle ".alpha./2", which permits to manufacture with the same parts two types of reservoirs: the first one for horizontal installation and the other one for inclined installation, at an angle ".alpha.".Suitable grooves, provided in the walls, of the two parts cooperate in both cases to form the transfer channel parallel to the plane of liquid.The invention is particularly useful in hydraulic braking systems for automotive vehicles.

Abstract: The object of the invention is a synchronized hydropneumatic control of clutch and gearbox.In accordance with the invention a hydropneumatic servomotor clutch control has been provided which includes a jack the piston of which is assisted by a pneumatic motor and a master cylinder which feeds the said jack with hydraulic fluid and controls the feed of air to the said motor, characterized in that the control chamber of the said jack is connected to the hydraulic circuit for locking/unlocking the gearbox, the feed to the said circuit being carried out through a valve mounted in the piston. The admission of the hydraulic fluid from the master cylinder having as its effect during a first period the closing of the said valve, thus interrupting the admission of fluid into the said chamber, then the causing of the transfer of the fluid contained in the latter towards the circuit for the gearbox which becomes unlocked in synchronism with the clutch.Application to controls of clutch and gearbox of vehicles.

Abstract: A master cylinder for a vehicle braking system. The master cylinder including a housing defining a bore therewithin with a piston slidably mounted in said bore. The piston head and the housing bore define a pressure chamber in communication with at least one brake actuator. A conventional annular ring cooperates with the wall of the housing bore and with a radial surface of the piston head for controlling fluid communication between a supply chamber of the master cylinder which communicates with a reservoir and the pressure chamber. The annular ring has a lip which projects toward the radial surface so as to form a non-return valve which prevents fluid communication from the pressure chamber toward the supply chamber when the master-cylinder piston is out of its rest position.

Abstract: A sealing device is mounted in the bore of a housing in which a piston is slidably mounted. A fluid tight seal is mounted between a shoulder of the housing and a washer circumscribing the piston. The washer has an outer diameter substantially equal to that of the bore and comprises an outer annular groove in which at least one fixing element is disposed. Each fixing element comprises a tongue-shaped portion penetrating through a corresponding radial bore defined at the bottom of the annular groove. When the piston is inserted through the washer, the fixing elements are moved radially towards the outside of the washer through the tongue-shaped portions and penetrate into a facing annular groove formed in the bore.

Abstract: The hydraulic master-cylinder of the invention is of the kind having a valve ring made of elastomeric material mounted on the head of a piston adjacent to the pressure chamber. The master-cylinder further includes a safety valve in the pressure chamber. The safety valve is guided on the piston head and is adapted to sealingly cooperate with both one face of the valve ring and a shoulder provided on the piston head. The safety valve is biased toward the valve ring by a spring abutting on a stop fixed relative to the piston.

Abstract: A fluid reservoir is made of non magnetic material and comprises two chambers communicating with a common well. A float is disposed in the well and bears a permanent magnet, and a switch is disposed outside the reservoir. The switch is actuated by the magnetic field of the magnet when the float is at a predetermined level in the reservoir.

Abstract: The invention relates to a failure detector for a dual hydraulic circuit such as a dual brake circuit in a motor vehicle. The detector comprises a movable piston assembly so as to define in a bore on opposite sides thereof two pressure chambers. Switch means are provided to make electrical contact when the movable assembly moves in certain direction from a central idle position due to pressure imbalance between the chambers. The movable assembly comprises a sleeve acting with the switch means and two resilient discs. The sleeve is mounted in a core fixed to a plug mounted in the bore and having the same axial length as the sleeve. The two discs are sealingly slidable along the bore and mounted in a fluid-tight manner on two axial projections attached to the opposite sides of the core and being smaller in diameter than the core.