| 摘要 |
A pneumatic piston/cylinder unit (1) comprises an outer cylinder (2) having a cylindrical inner surface (3), and an inner cylinder (4) projecting from one end of the outer cylinder (2) and having a cylindrical outer surface (5) which is slidingly engaged with the cylindrical inner surface (3) of the outer cylinder (2) so as to permit telescopic movement between the inner cylinder (4) and the outer cylinder (2). A bearing sleeve (31) is fitted on the end of the outer cylinder (2) from which the inner cylinder (4) projects. At least one internal projection (32) on the sleeve (31) engages in at least one groove (30) in the outer surface (5) of the inner cylinder (4) so as to control relative rotation between the inner cylinder (4) and the sleeve (31), whilst permitting relative axial movement between the inner cylinder (4) and the sleeve (31) during telescopic extension and retraction of the unit. The sleeve (31) may be provided with at leat one external projection (33) engaging in at least one aperture (34) in the outer cylinder, (2), or alternatively the sleeve may be adapted to be rotated by a drive arrangement in order to effect rotation of the inner cylinder (4) during extension and retraction. |
