| 摘要 |
According to the present invention, a motor-generator (27) is mechanically linked to an engine (21) and a hydraulic pump (23). The hydraulic pump (23) supplies pressurized oil to cylinders (12D)-(12F) of a work device (12), to a traveling hydraulic motor (25), and to a rotating hydraulic motor (26). The rotating hydraulic motor (26) cooperates with a rotating electric motor (33) and drives a rotation device (3). A HCU (36), when a rotational operation and boom raising operation composite operation is performed in a speed reduction mode (LSMODE), reduces the output of the rotating electric motor (33), rotating hydraulic motor (26), boom cylinder (12D), etc. such that the ratio between the rotational speed of an upper rotating body (4) and the operating speed for raising a boom (12A) is maintained at the ratio in a normal mode (NMODE). |
