CONTROLLER FOR EARTH-REMOVING PLATE

PROBLEM TO BE SOLVED: To increase the speed of extension of master and slave cylinders equally by efficiently controlling the quantity of a fluid fed to two fluid cylinders by combining the places of the working of a directional control valve, a fluid reproducing valve and a selector valve. SOLUTION: When a selector valve 26 is positioned at the right place of working and a fluid reproducing valve 25 at the left place of working and a directional control valve 24 at the right place of working, a hydraulic fluid from a pump 27 is flowed through a head-side fluid chamber 21 for a fluid cylinder 18. The fluid cylinder 18 is worked as a master cylinder, and the fluid discharged from a rod-side fluid chamber 20 is flowed through a head-side fluid chamber 21 for a fluid cylinder 19 worked as a slave cylinder through the selector valve 26. Accordingly, the reproduction of the fluid at 1 first stage is conducted, and the speed of extension of the cylinders 18, 19 is increased. The speed of extension of the fluid cylinders 18, 19 is further accelerated by combining the fluid discharged from the rod-side fluid chamber 20 for the fluid cylinder 19 with the fluid flowed into the head-side fluid chamber 21 for the fluid cylinder 18 through the reproducing valve 25 from the pump 27.