| 摘要 |
PURPOSE: To shorten the length of a recess and to narrow the width of the recess. CONSTITUTION: A prestressing apparatus which tenses a reinforcing cable in the recess or shaft of a structure has a main cylinder-piston units 15 and 17 and a counterforce cylinder-piston units 16 and 22. The pistons 17 and 22 are connected to a fixed arm 22 through their piston rods 39 and 40 and the cylinders 15 and 16 are connected to a movable arm 10. The main cylinder- piston units 15 and 17 disposed in the middle of the arms 2 and 10 and the off-centered counterforce cylinder-piston units 16 and 22 doubly act. Piston chambers 33, 35, 36 and 37 are hydraulically cross-connected. Since the counterforce piston 22 has half the piston area of the main piston 17, the prestressing force V and counterforce G of the piston 22 are each one-half of the pressing force P. The free end of the arms 2 and 10 extending beyond the main cylinder- piston units 15 and 17 serve to transmit forces to the reinforcing cable. |
