Cylinder control device of hydraulic cylinder apparatus

A cylinder control device of a hydraulic cylinder apparatus comprising a cylinder body, a piston arranged in said cylinder body for reciprocatory movement, a plurality of working fluid chambers defined by the cylinder body and the piston, a working fluid source, and a plurality of conduits for supplying working fluid from the working fluid source to the working fluid chambers and discharging working fluid therefrom to a fluid discharging place of a working fluid circuit, the cylinder control device comprising:

• a two-position, directional control valve operation to control the supply of working fluid to the working fluid chambers and the discharge of working fluid therefrom to thereby switch the movement of the piston from one direction to the other direction, the two-position, directional control valve having a pilot chamber containing working fluid therein for moving the two-position, directional control valve between two positions when a change occurs in the pressure of working fluid in the pilot chamber which is connected to the fluid discharging place of the working fluid circuit;
• and
• a control valve connected to the pilot chamber of said two-position, directional control valve and movable between two positions or open and closed positions for causing the pressure in the pilot chamber to vary, the control valve being moved between the closed position and the open position by a change in the pressure in the conduit in communication with the working fluid source, and the pressure in the conduit in communication with the working fluid source being raised when the piston is in one end position to move the control valve from one position to the other position, thereby causing the pressure in the pilot chamber to vary and moving the two-position, directional control valve from one position to the other position.