Patent ID: 11927205
Assignee: KOMATSU LTD.
Field: Civil engineering (Other fields)
Classification: CPC F  E | IPC E  F

Claim 7:
8. The hydraulic system according to claim 7, further comprising:
a boom lowering first pilot oil passage that applies a pilot pressure to one end part of the boom first direction switching valve when a boom operation lever is subjected to a lowering operation to retract and operate the boom hydraulic cylinder;
a boom lowering second pilot oil passage that applies a pilot pressure to one end part of the boom second direction switching valve when the boom operation lever is subjected to the lowering operation; and
a boom pressure reducing valve interposed in the boom lowering second pilot oil passage,
wherein the boom second direction switching valve blocks the boom second bottom oil passage and the boom second rod oil passage, respectively, when being disposed at a neutral position, and
the controller decompresses the boom lowering second pilot oil passage by the boom pressure reducing valve when the pressure of the bottom chamber of the boom hydraulic cylinder exceeds the preset pressure threshold.