| 摘要 |
An apparatus for hydraulically operating a rear cover, covering top or the like (1) on a vehicle, with at least one double-acting hydraulic working cylinder (3), which, on the one hand, is connected to the vehicle and, on the other hand, to the covering top, includes working chambers (8, 9) in connection with each one side of a switched pressure source (12) via one check valve (10, 11) each, wherein both of the check valves have an mutually releasing device and each of the working chambers parallel with respect to the check valves is kept via a pre-stress valve (15, 16), which steers into the tank, at a specified pressure level. To realize, in a simple and safe way, a passive wedging protection, in at least one connection line (4, 5) to the working cylinder (3), a line (22) enters the tank (17), in which a proportional pressure valve (23) is inserted which is controlled by the control electronics and is equal to the exact pressure that is necessary for the movement of the covering top (1) or the like.
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