| 摘要 |
PURPOSE: To protect the threaded part against damage at the time of coupling by holding the heavy cover of a vessel for transporting and carrying a radioactive material concentrically with the vessel and lowering them while controlling the force acting on the threaded part by turning the cover. CONSTITUTION: A stationary member 1 is secured to a vessel 5 concentrically thereto through a disc type member 19 and a coupling member 20. A platform 2 is movable in the direction of central axis 12 and a turnable cover 4 is fixed to a fixing section 3. When the cover 4 is screwed or removed, pressure in a gas spring bellows 7 is regulated to a reference level and then reduced slightly in order to lower the platform 2 slowly until the platform 2 touches the internally threaded part of vessel 5. Subsequently, the cover 4 is screwed into the vessel 5 by a continuous rotary driving means 9 while sustaining the force acting in the axial direction 12 within a limit. Consequently, the threaded part can be protected against damage at the time of coupling. |
