| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic circuit for boom cylinder combination having floating function, saving energy by lowering a boom with its dead weight during flattening and leveling work using an excavator and supplying an operating oil discharged from hydraulic pumps to another actuator. <P>SOLUTION: The hydraulic circuit comprises a boom cylinder combination spool 3 having a first internal passage 3a formed on one side of the boom cylinder combination spool 3 for connecting the hydraulic pumps 1, 2 to a large chamber 6b of a boom cylinder 6 during switching, a second internal passage 3b formed on the other side of the boom cylinder combination spool 3 for connecting the operating oil from the hydraulic pump 1 to a hydraulic tank 18 during switching, and a third internal passage 3c formed on the other side of the boom cylinder combination spool 3 for converging the operating oil from a small chamber 6a and the large chamber 6b of the boom cylinder 6 and connecting it to the hydraulic tank 18 during switching. <P>COPYRIGHT: (C)2004,JPO</p> |
