| 摘要 |
<p>The safety device prevents uncontrolled lowering or raising of hydraulically supported loads, e.g. in vertical presses. Between two or more withdrawal and holding rams (9) for the load on the one hand and the working pressure source (10) on the other are differential-pressure-operated valves working together. For each ram there can be two controlled non-return valves (17a,17b;19a,19b) indirectly differential-pressure-operated, and one flow-control valve (21) held hydraulically in equilibrium in the middle position and directly differential-pressure-operated. The latter valve is controlled by a branch pipe (26a,26b) from each of the working pressure pipes (18a,18b) between source and rams, the branch pipe being situated between the non-return valves.</p> |
