| 摘要 |
A driving device comprises a source of hydraulic fluid under pressure, a working arrangement (6) having a working chamber (7) intended for receiving hydraulic fluid and a working member (8) adapted to be put in motion on respective fluid supply to and fluid evacuation from the working chamber. Conduits (20, 29, 30) are provided for respective supply to and evaluation from the working chamber (7) of hydraulic fluid. A valve (16) is adapted to, in a first state, direct fluid to the working chamber and, in a second state, allow evacuation of fluid from the working chamber. Means (17) are provided for returning the working member to a starting position. These means comprise an ejector arrangement adapted to generate a negative pressure evacuating the working chamber as a consequence of flow of fluid through the ejector arrangement. The hydraulic fluid source is constituted by a high pressure washing unit known per se or of an arbitrary nature.
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