The hybrid shovel includes an engine 11 that is controlled to rotate at a constant number of revolutions, a motor generator 12 that assists the engine 11, a controller 30 that controls the drive of the motor generator 12, (Not shown). The controller 30 assists the engine 11 with the motor generator 12 when the rotational speed of the engine 11 is lowered by the load of the main pump 14 than the predetermined rotational speed, The assist output of the engine 11 by the electric motor generator 12 is reduced before the number returns to the predetermined number of revolutions.
展开▼
