| 摘要 |
PURPOSE:To eliminate the unnecessary motion of an electromagnetic valve and to elongate the service-life of the valve, by setting in advance the range of the input value from a control lever and outputting a control signal, by which a hydraulic actuator is pushed toward one end-side, when the input value is deviated from the said range. CONSTITUTION:When the input command voltage X, which corresponds to the control input of a control lever, lies between X1 and X2, both of which are preset values, a command voltage value X', which is equal to the input command voltage X, is output from a comparator 16. When the input command voltage X is either smaller than X1 or greater than X2, voltage values X3 and X4, which correspond to a state in which the piston of an actuator 1 is located at point C or D both situating outside the stroke ends, respectively, are output from the comparator 16. With this constitution, solenoids 4a-7a of an electromagnetic valve, through which the pressure oil is supplied to or discharged from the actuator 1, are controlled by the output from the actuator 16. Therefore, by bringing the control lever to the maximum of minimum position, the electromagnetic valve can be placed under the open control, thereby eliminating the lost motion of the electromagnetic valve.
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