To carry out speedy work even when a heavy load is applied by performing control such that when a power active mode is selected, a product between a pump discharge output one stage higher than the active mode becomes an equal horsepower curve of P-Q of the power active mode.
A construction machine such as a hydraulic shovel has a variable displacement pump 11 driven by an engine 1 and, during normal running, the pump 11 is controlled by a control means 30 such that a product between a load pressure applied to this and its discharge capacity becomes a roughly specified constant value. In this case, when an active mode switch 8 is ON- operated, a product between a pump discharge pressure P and a pump discharge quantity Q becomes an equal horsepower curve of P-Q of the active power mode which is higher than the specified value of normal running. Further, when a power active mode switch 9 is ON-operated, control is made to realize an equal horsepower curve of P-Q of the power active mode one stage higher than that of the active mode.
TAKAMURA FUJITOSHI
TANAKA JUNICHI
