Distributing unit for a dual action hydraulic electro-distributor

A distributing unit for a dual-action hydraulic electro-distributor of the type comprising, firstly, a distribution stage including a casing provided with a bore and closed at its opposite ends, a slide mounted in said bore so as to slide between two end positions, said bore defining end chambers at the ends of said slide, spring means in said end chambers acting on said slide to return the slide to a central or neutral position and, secondly, a piloting stage with valves controlled selectively by solenoids, each of the said valves being adapted, when actuated, to communicate the feed pressure to a corresponding end of the slide and, when not actuated, to set the corresponding end to return to a tank, wherein untimely displacement of the slide is avoided by the provision wherein the slide comprises a tubular element with two push rods mounted to slide in an axial direction with a seal at its ends, the two push rods being held in abutment with shoulders formed at the ends of the slide by the action of the feed pressure which is exerted on the surfaces of the push rods facing towards one another, through an orifice formed in the central portion of the slide, the opposed surfaces of the push rods projecting out of the slide into said end chambers and being kept applied to the end walls of the bore when the solenoids ae not energized, the control pressure coming from the piloting stage being communicated to two symmetrical annular chambers defined in the bore of the casing, two bearing surfaces of small diameter formed at the ends of the slide, and bearings in which the said ends of the slide are mounted for sliding movement, the said annular chambers having a section S which has a value relative to the section S of the push rods so that s<S <

• 2s, said push rods having passage means connecting the end chambers to return to the tank.