| 摘要 |
<p>A hydraulic circuit for heavy equipment is provided, which can prevent signal pressure exceeding a predetermined pressure from being formed in a pilot signal path (11) provided in a switching valve to sense whether the switching valve has been shifted in a hydraulic system that minimizes the discharge flow rate of a hydraulic pump when a working device such as a boom is not driven. The hydraulic circuit includes first to fourth hydraulic pumps (P1,P2,P3,P4) connected to an engine, first switching valves (1,2) installed in flow paths of the first hydraulic pump (P1) and shifted to control hydraulic fluid fed to a working device, second switching valves (4,5,6) installed in flow paths of the second hydraulic pump (P2) and shifted to control hydraulic fluid fed to a working device, third switching valves (7,8) installed in flow paths of the third hydraulic pump (P3) and shifted to control hydraulic fluid fed to a swing device, a pilot signal path (11) for sensing whether the first to third switching valves are shifted, a throttling part (10) installed in the pilot signal path (11) to form a signal pressure, and a valve (21) installed in a parallel flow path branch-connected to the pilot signal path and supplying the signal pressure in the pilot signal path (11) to the pilot signal pressure supply path (22) when a signal pressure exceeding a predetermined pressure is formed in the pilot signal path (11).
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