PURPOSE: To make switching time between advancing and retreating of a main hydraulic cylinder to resist against a switching resistance whith changes by the characteristics of viscous fluids by adjusting a time for energizing the sole noid of an electromagnetic four-directional valve for switching feeding and draining of pressurized oil to and from the main hydraulic cylinder, by timer setting time.

CONSTITUTION: A relay X1 is energized and (a) contact point X1 of a circuit is closed by turning a switch SW1 ON when the viscous fluid pump is operated, and thus electricity is conducted to respective pairs of solenids SOL1 to SOL4 on a plurality of electromagnetic four-directional valves 7 and 12. By turning the switch SW2 to, for example, am A contact point when the main hydraulic cylinder is advanced, the main hydraulic cylinder advances and reaches its stroke end and a proximity switch LS1 is actuated, and this (a) contact point LS1 is closed, thus, a plurality of timers T1 and T2 start counting simultaneously. Then, by adjusting setting time on one side timer T1 energizing of the solenid SOL2 on one side electromagnetic four-directional valve 12 for switching feeding and draining of pressurized oil is delayed.