| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a slewing control unit which enables an operator to arbitrarily perform an on/off operation of a solenoid valve for making circuits for slewing communicate with each other. Ž<P>SOLUTION: The solenoid valve 54 for making the circuits for slewing communicate with each other is opening/closing-controllably installed in a passage which is provided in such a manner as to be capable of short-circuiting between the circuits for slewing by bypassing a rotary motor. When the solenoid valve 54 is opened at the stop of the slewing, a slewing brake function performed by a hydraulic fluid confined in the circuit for slewing can be released. The solenoid valve 54 is opened/closed by a rocker switch 26 installed in a cab, a button switch 62 on a control lever capable of being operated by an operator in a slewing operation posture as-is separately from the rocker switch 26, or a stepping-type switch 63 such as a foot switch. When the rocker switch 26 is in an on-operation state, the button switch 62 or the stepping-type switch 63 is operated to an on-state so that a relay 61 can be turned on, and the solenoid valve 54 is controlled for opening. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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