JACK FOR PC TENSIONING MATERIAL WITH AUTOMATIC FIXING FUNCTION

PROBLEM TO BE SOLVED: To enhance the safety and achieve a quick operation to give a tension to a PC tensioning material. SOLUTION: This jack 1 for PC steel bar equipped with a function to perform automatic fixation is composed of a hydraulic jack 2 grasping a PC steel bar 12 and tighten, a socket wrench 3 including a gear part 8 formed at the periphery of a socket body 7 to be fitted to a nut for fixing 13 and installed ahead of the hydraulic jack 2 in continuity in such a way as capable of rotating coaxially and round its own axis, a hydraulic motor 4 installed on the hydraulic jack 2 and giving a rotary power to the socket wrench 3 through the gear part 8, a hydraulic system for jack furnished with a hydraulic pump and selector valve and supplying a working fluid at the specified pressure to the hydraulic jack 2, and a hydraulic system for motor equipped with a hydraulic pump, selector valve and relief valve and supplying the working fluid at a pressure below the set level to the hydraulic motor 4. A ratchet device capable of being changed over in the ratchet teeth direction is installed between the gear part 8 of socket wrench 3 and the output shaft of the hydraulic motor 4. Further an elongation measuring means 18 is installed to sense the revolving speed of either of the socket wrench 3 and hydraulic motor 4 and display it upon converting into the elongation of the PC tensioning material.