| 摘要 |
A hydraulic jack having two consecutive and completely different actions and its hydraulic operating means, the jack responding to the control order given by the operating means in the form of the supply pressure on a first input of the jack and the control pressure on a second input of the jack, while automatically effecting two consecutive actions in the same direction, the first action being a travel of large amplitude (naturally with a low force), while the second action develops a large force proportional to the control pressure (with a zero or very small travel), the disappearance of the control order resulting, by the operating means which apply the supply pressure to a third input of the jack, in the return movement of the travel of large amplitude only.
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