TIMER VALVE OF MECHANICAL BRAKE DEVICE FOR HYDRAULIC MOTOR

PROBLEM TO BE SOLVED: To provide a single spool-shaped timer valve for generating the specified delay time on the operation restoration from the releasing state of a mechanical brake device for a hydraulic motor. SOLUTION: A timer valve 20 provided in a housing bore 22 is provided a single spring pressed control spool 44, capable of being moved between the mechanical brake releasing position in which a pilot hydraulic pressure port 36 is fluid-communicated with a supply/discharge port 38 and the mechanical brake operating position in which the supply/discharge port 38 is fluid- communicated with a drain port 42. A drain chamber 50 and a pressure signal chamber communicated with each other through a spool through communicating passage 60 are provided on the mutual opposite sides of the control spool 44 in the bore 22. The pressure signal chamber is communicated with an inlet port 26 in which a check valve 58 is provided. An orifice 62 for restricting the flow of pressure oil from the pressure signal chamber to the drain chamber and for supplying the desired delay time by controlling the movement of the control spool 44 from the releasing position to the operating piston is provided in the through communication passage 60.