| 摘要 |
A first coupling piece (4) includes a housing defining a cylindrical ring-shaped cavity with an opening (8) formed in the curved housing wall (7) receiving a second coupling piece (5). The section of the second piece received by this cavity has two walls (9, 10) tightly abutting against the inside of the cavity and centrally positioned relative to each other to form a circular opening (15) in between, with which the first coupling piece communicates. |
