| 摘要 |
A rear support device having a rear support element, an abutment, and a mechanism for immobilizing the abutment with respect to the rear support element. The device includes a first wedge connected to the rear support element, and a second wedge connected to the abutment, at least one of the two wedges being movable to occupy at least two stable positions with respect to the piece to which it is connected, such that various portions of a wedge can be in contact with the other wedge.
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