PURPOSE: To raise controlling accuracy in a hydraulic actuator by using a relatively inexpensive solenoid changeover valve.
CONSTITUTION: Falling control of a hydraulic motor main body is made by a solenoid changeover valve 35. Effective pressure of the motor and its time- lapse variation are obtained with pressure sensors 51, 52, an effective pressure arithmetic means 61 and an effective pressure time-lapse variation arithmetic means 62. An operation command index number of the solenoid changeover valve 35 is calculated with a solenoid changeover valve operation command index number arithmetic means 63 on the basis of the obtained values. Changeover control of the solenoid changeover valve changeover control means 64 on the basis of the operation command index number.
EDA KENJI
TAJI HIROSHI
YUTANI JUKO KK