| 摘要 |
The central part comprises two tensioned parts (5,6) between which the withdrawal parts (3) are displaceable. The tensioned parts are tensionable (4) against one another in order to lock the withdrawal parts (3). The central part has four longitudinal recesses (7) with a cross-section which is complementary to the external cross-section of the withdrawal parts. The recesses are centrally located so that in pairs they form guides for the withdrawal parts. Two of the withdrawal parts (3) are fastened in the one end piece and two in the other, and in both end pieces are arranged alternately in the central part. The withdrawal parts have a length which approximately coincides with or is less than the length of the tensioned parts (5,6). The withdrawal parts are located in a common plane. The tensioned parts (5,6) have the same shape and are produced by cutting a profile bar. |
