Abstract: The distributor comprises a star-shaped rotor (2) arranged between two concentric components which are spaced axially and are fixed in rotation to a second valve portion (60); a C-shaped centering return spring (40) is arranged around the rotor (2) and cooperates, by its facing ends, with a projection (100) of one of the arms (10.sub.1) of the rotor and with adjacent projections of the second valve portion.

Abstract: The power assisted steering mechanism consists of a rack body (20) guided and confined to slide in the steering casing (10) and joined centrally through the lateral wall of the casing (10) by shaft components (31), to a steering linkage of a vehicle, the opposite ends (23) of the rack being joined by rods (51) to pistons (50), single or double acting, each sliding in a cylinder (41) attached to the end (11) of the casing (10) in the extension of the latter.

Abstract: The power assisted steering system, particularly of the type with central output, incorporates a body (10) forming a housing for a cooperating pinion (12) and rack (11) assembly. The rack is guided in the central portion (10.sub.1) of the body and is joined by a rod (40) to at least a first piston (30a) movable in a cylinder consisting of a component in the shape of a cylindrical bell (20a, 20b) attached to one end of the body (10) and itself consisting of a rolling membrane (31) joined at its periphery to the component in the shape of a bell, and of a tubular support component (24) fixed to the rod (40) and coaxial with the latter. Also described are variants with a twin circuit incorporating a second piston carried by the rod and sliding so that it is sealed relative to a central stationary component passing longitudinally through the rack.

Abstract: The cooperating double-acting piston/cylinder assistance assembly of the rack (20) incorporates a cylinder (24) firmly fixed to one end of the rack, in the extension of the latter and a stationary piston (40) fixed to one end of a hollow rod (42) whose other end (43) is fixed centrally in the steering casing (10), the hollow rod enclosing two separate fluid passages (45, 47) for supplying the chambers which are in opposition (46, 48), on each side of the piston (40), with actuating fluid under pressure coming from a distribution valve (30) mounted in the casing (10).

Abstract: The mechanism incorporates at least one assistance unit consisting of a fixed piston (44) supported by a hollow rod (43) and of a cylinder (32) housed in a bore (30) of the rack (11), the chambers (60, 61) being supplied through separate passages (62, 63) extending through the hollow rod (43). The mechanism, advantageously of the type with central output and with a double circuit, incorporates a double circuit distribution valve mechanism (20) for supplying selectively the pairs of chambers (60, 61) on each side of the pinion (12) of the rack (11).

Abstract: A power steering mechanism for a vehicle which comprises a rotary steering control member and a driving piston connected to a member in the steering gear of the vehicle. The piston separates two pressure chambers in the housing. The mechanism also comprises a shaft of which the first end defines a screw cooperating with a nut attached to the piston. A pressure fluid distribution valve is adapted to control fluid communication between the pressure source formed by a pump, and the two pressure chambers. The distribution valve is of the rotary type and comprises a sleeve moving as a whole with the rotary control member and a rotor moving in unison with the shaft. The shaft and the rotor are connected to opposite ends of a torsion bar. The second end of the shaft is broadened and contains a bore. This other end is provided with orifices and defines the sleeve of the rotary valve, in which the rotor is mounted for rotation.