| 摘要 |
PROBLEM TO BE SOLVED: To provide a control device which can accurately control a jack device of a shielding jack or the like even at a low speed. SOLUTION: In a control device to control protruding-retreating speed of a piston rod 2 of a shielding jack 1 arranged in a shielding excavation propelling machine, a solenoid directional control valve 13 to switch the supply direction of oil pressure is arranged in the middle of hydraulic piping 12 arranged between a hydraulic pump 11 and the shielding jack 1, and a first solenoid opening- closing valve 14 to open and close an oil passage is arranged between this solenoid directional control valve 13 and a rod side cylinder chamber 3A of the shielding jack 1, and bypass piping 15 to bypass this first solenoid opening- closing valve 14 is provided. A second solenoid opening-closing valve 16 is arranged in the middle of this bypass pipe line 15, and a high speed solenoid opening-closing valve to perform opening operation by a pulse signal train is used as this second solenoid opening-closing valve 16. |
