Patent ID: 8104276
Filing Date: 2012-01-31
Classification: E02F,F15B

Abstract:
1. A hydraulic circuit for preventing a bucket separation from a bucket rest during transportation, the hydraulic circuit including: first and second hydraulic pumps, a boom cylinder driven by shifting a spool for the boom cylinder installed in a flow path of the first hydraulic pump, an arm cylinder driven by shifting a spool for the arm cylinder installed in a flow path of the second hydraulic pump, a boom confluence logic valve for making a hydraulic fluid fed from the second hydraulic pump join a hydraulic fluid of the boom cylinder, a first port formed to connect with a chamber of the boom cylinder in a housing in which the spool for the boom cylinder is shiftably installed, a second port formed to connect with a hydraulic tank in the housing, and a first orifice formed between the housing and a land part of the spool for the boom cylinder located between the first port and the second port such that during transportation, any hydraulic fluid leaking from the second hydraulic pump to the chamber of the boom cylinder drains to the hydraulic tank through the first orifice to prevent a change of stroke of the boom cylinder, wherein the first orifice is larger than a second orifice formed between the housing and the land part of the spool for the boom cylinder and located between a high-pressure flow path formed in the housing and the first port.