PURPOSE: To permit the concurrent operation of slewing and arm by a method in which an arm control valve is connected to the downstream side of a control valve for slewing in tandem for the neutral position but in parallel for the operational position, and a pilot pressure receiving chamber is provided on both ends of the spool of the arm control valve.
CONSTITUTION: Plural control valves 24W27 are connected in parallel to a center bypass in tandem, and when the uppermost control valve 24 is switched and operated, in the control valves 25W27 on the other downstream side. tilot pressure chambers 40 and 52 are provided to both ends of the spool 37 of the control valve 27 for arm positioned on the downstream side in relation to the control valve 26 for a motor in an oil pressure circuit connected through a prallel path. Also, a pressure receiving chamber 48 ncorporated with a piston is provided in any one of both pilot pressure chambers 40 and 52, and oil pressure is introduced into or discharged from the pressure receiving chamber to regulate the movement of the spool. By this, slewing operation and arm operation can be concurrently attained.
JP53132598B | ||||
JPS4411269Y1 | 1969-05-09 |