| 摘要 |
A closure alarm contains a switch formed of a pair of axially aligned rounded-end contacts spring biased into end-to-end contact. A pivoted operating arm has a thin, knife - like insulating portion which is interposed between the contacts when the lever is in its active position. Opening movement of the closure, when the operating lever is in its active position, contacts the operating lever to pivot the lever to withdraw the insulating portion, allowing the contacts to close an alarm circuit. The lever is frictionally restrained from returning to its initial position, so the alarm is latched. The operating lever can be pivoted 180 degrees to an inactive position in which a second thin, knife-like insulating portion separates the switch contacts but the lever is out on the path of the closure, so the alarm circuit is off. An arm is mounted on the closure by a bracket in one of two positions: active or inactive. If the operating lever is positioned between its active and inactive positions and the arm is placed in its active position, an insulating portion of the arm is aligned with the switch contacts. Therefore, if the closure is opened, the contacts close the alarm circuit, but if the closure is then closed, the arm moves with the closure to again separate the contacts and silence the alarm. Thus, a non-latching mode of operation is provided.
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