| 摘要 |
<p>Halting is effected by retractable cams and a distributor allows flow into and out of a chamber in the lifting mechanism, and a drain is provided between distributor and chamber. A logic circuit has an AND-gate for each chamber, and whose output is connected to the distributor, while its input is connected to a control for forward or return movement of the lifting mechanism. The second input of this gate is connected to the output of a second AND-gate having the same number of inputs as there are cams and these inputs are each connected to the output of an OR-circuit. The two inputs of the latter circuit are connected, one directly and the other via an adjustable time-delay switch, to the control unit retracting the cams.</p> |
