PURPOSE: To prevent degradation of maneuverability when correction of rotation speed of a prime mover is required by adjusting a target rotation speed to a corrected rotation speed on the basis of the load working on an actuator by a load detecting means and information regarding rotation speed.
CONSTITUTION: A target rotation speed Nx with respect to a displacement quantity X of a fuel lever is calculated by a target rotation speed calculation device 51 and, simultaneously with the input into a calculating machine, a second correction value ΔN2 of rotation speed which can be determined by the size of the target rotation speed Nx is calculated by a second correction rotation calculation device 53. A pump delivery pressure force Pp detected by a pressure sensor 43 is inputted into a first correction rotation speed calculation device 52 and a first correction value ΔN1, to which hysteresis is given to the input/output relations, is outputted. The first and the second correction values ΔN1, ΔN2 are respectively inputted into a correction rotation speed selection device 54 and the selected small values are outputted as rotation speed correction value ΔN. When a switch 56 is turned on, the rotation speed correction value ΔN is added to the target rotation speed Nx and outputted as a rotation speed command value Ny and when the switch 56 is turned off, the target rotation speed Nx is outputted as the rotation speed command value Ny.
SUGIYAMA GENROKU
HIRATA TOICHI
