Modulating control valve for hydraulically operated winch

Claim 1

A hydraulically operated winch comprising a rotatable winch drum, a power train having a normally disengaged clutch being hydraulically engageable for operatively coupling a power input means with a winch drum drive shaft, a normally engaged brake effectively securing the winch drum drive shaft against rotation while being hydraulically releasable to permit rotation of the winch drum drive shaft and a clutch normally coupling the winch drum drive shaft with the winch drum while being hydraulically disengageable to permit free-wheeling of the winch drum, a source of fluid under pressure, and a modulating control valve having a valve body defining an inlet chamber in communication with the fluid source and a bore, the bore being in communication with the inlet chamber, an actuating chamber for releasing the normally engaged brake, an actuating chamber for engaging the normally disengaged clutch and an actuating chamber for disengaging the normally engaged clutch, a single regulating spool being slidable in a bore with resilient means urging the regulating spool into a centered position in the bore wherein the spool communicates all of the clutch and brake chambers with fluid drain means, the single regulating spool being movable in a first direction of travel from its centered position for variably communicating both of the actuating chambers for the brake and the normally disengaged clutch with the inlet chamber, the regulating spool being movable in a second direction of travel from its centered position for variably communicating the brake actuating chamber with the inlet chamber, the regulating spool being further movable in its second direction of travel for communicating the actuating chamber of the normally engaged clutch with the inlet chamber and means for selectively modulating fluid pressure within the inlet chamber.