| 摘要 |
PURPOSE:To provide an optimum flow dividing characteristic at the time of mounting respective attachments, in the hydraulic drive device of a construction machine provided with flow dividing compensating valves having positive gradient characteristic and capable of exchanging a plurality of sorts of attachments. CONSTITUTION:An attachment changeover switch 58 having three output terminals, a bucket terminal 58a, a crusher terminal 58b, a breaker terminal 58c, and outputting a corresponding changeover signal S by changeover operation of an operator, is provided. In case of mounting a heavy crusher, at a compound operation for hoisting a boom and drawing an arm, a flow dividing characteristic computing part for a light bucket is changed over to a flow dividing characteristic computing part for a heavy crusher according to the changeover signal, and as to control force to be given with respective drive parts 35c-40c of flow dividing compensating valves 35-40, values suitable for the heavy crusher are computed. Hereby, the optimum flow dividing characteristic for a heavy attachment is obtained, and the boom is sufficiently hoisted by the compound operation for hoisting a boom and drawing an arm. |
