| 摘要 |
A float is moved upwardly or downwardly by liquid being added to a liquid holding tank. The float carries a first permanent magnet which is moved by the float towards a second magnet which is separated therefrom by a liquid tight partition. The permanent magnets are arranged with like poles directed towards each other so that the permanent magnets will repel each other and movement of the first permanent magnet in response to a liquid level change will cause the second permanent magnet to be moved in response to the repelling force. The second permanent magnet is positioned in line with a depressable control member of a normally closed valve in a gas line. Movement of the second permanent magnet against such control member depresses the control member to open the valve, allowing gas to flow from a storage tank to a piston in a normally closed valve that is located in a second line leading from the gas supply to a horn. The gas pressure moves piston to open the valve and allow a flow of gas to operate the horn.
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