| 摘要 |
<P>PROBLEM TO BE SOLVED: To make a relationship between a boom operation amount and a vertical movement amount of an attachment tip in a vertical motion work performed by vertically moving the attachment tip constant regardless of a change in reach. <P>SOLUTION: When performing a boom hoisting motion which is an operation in a load direction, a pump flow is decreased on large reach and increased on small reach by correcting the pump flow, which is determined by the boom hoisting operation amount, according to the reach. Meanwhile, when performing a boom lowering operation in which the self-weight of attachment acts, the opening of a control valve is decreased on large reach and increased on small reach by correcting secondary pressure of a proportional valve 17 provided in a boom lowering side pilot line 14b according to the reach. This control makes stroke of a boom cylinder increase/decrease according to the reach. <P>COPYRIGHT: (C)2013,JPO&INPIT |
