Hydraulic winch control mechanism

Claim 1

A CONTROL MECHANISM FOR A REMOTELY OPERATED CABLE WIND ON A ROTATABLE CRANE BOOM COMPRISING, IN COMBINATION A REVERSIBLE HYDRAULIC MOTOR MOUNTING ON SAID BOOM AND COUPLED TO SAID WINCH FOR SELECTIVELY TAKING UP AND PAYING OUT THE CABLE THEREFROM, SAID MOTOR HAVING A PAIR OF HYDRAULIC SUPPLY AND RETURN LINES COUPLED THERETO, A SOURCE OF HYDRAULIC PRESSURE FLUID LOCATED REMOTELY FROM SAID BOOM AND SAID MOTOR, A ROTARY DISTRIBUTOR DEFINING SEPARATE PASSAGES FOR EACH OF SAID HYDRAULIC LINES INTERPOSED BETWEEN SAID SOURCE AND SAID MOTOR, A CONTROL VALVE FOR SELECTIVELY ADMITTING AND REVERSING THE FLOW OF HYDRAULIC PRESSURE FLUID THROUGH SAID HYDRAULIC LINES, A BRAKE MECHANISM MOUNTED ON SAID BOOM AND COUPLED TO SAID WINCH FOR STOPPING MOVEMENT THEREOF WHEN SAID MOTOR IS NOT OPERATED, SAID BRAKE MECHANISM HAVING A HYDRAULIC ACTUATOR FOR DISENGAGING SAID BRAKE, AND MEANS INCLUDING A SHUTTLE VALVE FOR COMMUNICATING HYDRAULIC FLUID TO SAID ACTUATOR UNDER THE INFLUENCE OF A PRESSURE DIFFERENTIAL IN SAID LINES TO RENDER SAID BRAKE MECHANISM INOPERATIVE INCIDENT TO OPERATION OF SAID MOTOR IN EITHER DIRECTION, SAID SHUTTLE VALVE BEING CONNECTED BETWEEN EACH OF SAID HYDRAULIC LINED AND SAIC ACTUATOR AND INCLUDING A BIDIRECTIONAL SLIDE ELEMENT WITH SUBSTANTIALLY EQUAL AREAS ON ITS OPPOSITE ENDS.