| 摘要 |
The surface box 13 comprises a two-part housing. The latter is made up of a bottom part 1 with an internal thread 4 and of a top part 5 which can be displaced vertically in the bottom part 1 and has an external thread 6. The top part 5 has, at the top end 36, an opening 37, which can be closed by a cover 9 borne by a bearing ring 8, and is open at the bottom end 38. The bottom part 1 has an annular-disc-like withdrawal- prevention means 2, 11 at the bottom end 39. The thread turns 40 of the internal thread 4 are formed by elevations projecting radially from the inner planar surface 14, and the thread turns 41 of the external thread 6 are formed by depressions made in the planar outer surface 15. The thread turns 41 of the external thread 6 extend, from the bottom end side 43, over approximately 2/3 of the height of the top part 5. |
