| 摘要 |
The device comprises an intermediate element (7) connected to each of two other elements (1, 3) by an articulation (8, 9) with cylindrical sliding surfaces (8a, 8b, 9a, 9b) centered on axes (8c, 9c) located outside the device and on the side opposite the tool (2). Ducts (100, 12, 14, 15), a slide valve (17) and a pump (16) make it possible to establish, between the sliding surfaces, a fluid pressure which is lower than or higher than the pressure prevailing around the articulations (8, 9) so as to interpose a film of fluid between the surfaces, making the articulations free or press these surfaces on one another in order to lock these articulations. <IMAGE>
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