Abstract: Hydraulic actuators are fed by a single flow-rate generator, each being connected to it through a proportional directional valve, the unit including a device for detecting the highest of the pressures prevailing upstream of the throttle provided by a controlled spool in the respective proportional directional valves, and, in each of these an actuation device to cause the compensating spool to respond to the highest of the upstream pressures thus detected.

Abstract: Hydraulic actuators are fed by a single flow-rate generator, each being connected to it through a proportional directional valve, the unit including at least one auxiliary valve fed by the flow-rate generator and producing a pressure which is normally equal to a regulation pressure increased by a constant, and in each proportional directional valve an actuating device causes the compensating spool to respond to the pressure produced by the auxiliary valve.

Abstract: A proportional distributor embodying a controlled slide valve and a pressure compensator slide valve associated with additional positioning means whereby the pressure drop in the controlled slide valve depends upon the difference between the working and load sensing pressures according to a linear function with a strictly positive coefficient and a strictly negative constant. Each compensator slide valve operates according to the same linear function or at least one of its proportional distributors has a compensator slide valve operating according to a different linear function.

Abstract: A proportional type hydraulic distributor incorporates a distributor slide valve including a feed chamber. It is provided with a pressure compensator device for regulating the feed pressure to the feed chamber according to the output (load) pressure of the slide valve. This device includes an inlet channel, an outlet channel communicating with the feed chamber and a stator communicating with the inlet and outlet channels. A compensator slide valve slides in a housing in the stator. A spring exerts an axial force on the compensator slide valve in the same direction as the force exerted on it by the output pressure and in the opposite direction to the force exerted on it by the feed pressure. An annular obturator member on the compensator slide valve isolates the inlet and feed channels and is acted on by a return spring on the compensator slide valve. The latter has a recessed part on which the obturator member slides without clearance.

Abstract: A progressive hydraulic distributor with a slide for controlling a hydraulic actuator. The distributor has an internal load sensing passage that detects the operating pressure in the hydraulic fluid inlet or outlet passage and superimposes this pressure on the action of the spring of a feed valve. Thus, the difference between the up-flow and the down-flow of progressivity in the slide of the distributor is constant.

Abstract: A spring return for the reciprocable slide of an hydraulic distributor. The return spring is trapped between flanges of opposed cup-shaped rings. The cup-shaped rings have conical sections which are positioned inside of the spring, but which do not contact the spring. Each cup-shaped ring has a transverse bottom, and each of the transverse bottoms surrounds the slide and contacts only a cylindrical centering section on the slide. The cylindrical centering sections on the slide are short, and each cylindrial centering section loses contact with the surrounding transverse bottom of the cup-shaped ring shortly after the slide moves relative to such cup-shaped ring.