Control unit for the supply of a work unit fed in parallel from a hydraulic station common to other units

Claim 1

In an arrangement having a plurality of hydraulically operable work units fed from a common hydraulic pressure source through parallel supply conduits, the improvement comprising: a control unit in the supply conduit of at least one of said work units, there being a fluid distributor and a pressure accumulator between said control unit and said one work unit; said control unit comprising a block defining a cylinder having an inlet form and an outlet to said supply conduit, said cylinder having an obturator therein urged by resilient means to a position in which it closes communication between said inlet and outlet, said resilient means being in a portion of said cylinder comprising a first chamber defined in part by said obturator; a relief valve in said block and a second conduit means communicating with said chamber, said outlet and said relief valve; and opposite sides of said relief valve communicating with further conduits leading, respectively, to a return tank and to said inlet, said further conduit leading to said inlet being arranged so that pressure in said inlet tends to close said relief valve, said relief valve, when open, providing communication between said outlet and said return tank.