| 摘要 |
<p>A hydraulic circuit for a construction machine is disclosed, which can prevent an energy loss of a hydraulic system by automatically reducing revolution of an engine when a working device such as a boom is not driven. The hydraulic circuit includes first to third hydraulic pumps (P1,P2,P3), a first switching valve (A), a second switching valve (B); a third switching valve (C), a confluence switching valve (8), a first shuttle valve (41) selecting any one of a pressure of a first signal line (34) in which a signal pressure is formed when the third switching valve (C) for working devices connected to the third hydraulic pump (P3) is shifted and a pressure of a second signal line (33) in which a signal pressure is formed when a switching valve (D) for traveling devices is shifted, and a second shuttle valve (42) selecting any one of the pressure selected by the first shuttle valve (41) and a pressure of a third signal line (32) in which a signal pressure is formed when switching valves (A and B) for the working devices connected to the first and second hydraulic pumps (P1 and P2) are shifted.</p> |
