| 摘要 |
PURPOSE: To simplify locking operation by releasing an observation window box, turning it, and hence bringing it closer to a second locking member. CONSTITUTION: A first insertion locking member 13 has a closing member 14. When an observation window box 10 is turned, the member 13 is introduced into a first reception locking member 21 mounted to the range of the front side of a turning frame 20. The reception locking member 21 is fixed to the outside of a wall part that forms the front side of the turning frame 20 and a support part 27 is fixed to the inside of the wall part, thus using a common fixed screw. The front side of the turning frame 20 is formed so that a worker approaches a second locking member 13' when the observation window box 10 is released and turned. |
