| 摘要 |
The controller comprises two hand switches and a circuit which is operated by said hand switches and consists of a plurality of logic switching elements, including a fluid-supplied control valve, which is switched by these elements, for reversing a fluid control medium. In order to improve the safety of the controller, an essentially identical, further circuit is connected in parallel with said circuit on the input side. The fluid-supplied control valve of the first-mentioned circuit communicates via the pressure medium of a common fluid-pressure source with the control valve of the further circuit, in series, in such a manner that an operating signal for a machine, which is to be set in motion, appears from the operating output of the second control valve when both control valves are in the seated position.
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