| 摘要 |
PROBLEM TO BE SOLVED: To improve boom raising/turning performance with the pump pressure of a third pump secured when boom raising/turning operation is conducted in a hydraulic circuit which employs a three circuits/three pumps system. SOLUTION: Based on the assumption that a third pump oil is merged into both first and second circuits A and B by a merging valve 22 when other actuator operations are conducted in both traveling operations, the hydraulic circuit performs switching the merging valve 22 into a third position H when the boom raising operation is conducted regardless of both traveling operations; and also merging the third pump oil discharged from the third pump 15 into the first circuit A to which a boom cylinder 6 belongs through a parallel passage 24, and blocking it to the second circuit B to which an arm cylinder 7 belongs by a turning control valve 21, when turning operation is further conducted. COPYRIGHT: (C)2012,JPO&INPIT |
