| 摘要 |
<P>PROBLEM TO BE SOLVED: To hold a revolving superstructure in a stopped condition by developing a fail-safe function in a circuit which uses the communication valve for communicating a motor discharge side duct with a tank or an inlet duct at least during slowing down revolution, when a fastening phenomenon occurs in a solenoid-selected communication selector valve which controls the supply/cutoff of pilot pressure to/from a communication valve. <P>SOLUTION: A shovel includes a lock valve 41 which is put into a non-exited condition during the opening operation of a lock lever for cutting off the supply of pilot primary pressure to a remote-control valve 12, the lock valve 41 being provided on the primary sides of communication selector valves 32, 33 for cutting off the supply of the pilot pressure to the communication selector valves 32, 33 in a revolution stopping condition. <P>COPYRIGHT: (C)2013,JPO&INPIT |
