| 摘要 |
An alarm switch of the manual call-point kind has a wall-mounted box with a front plate (102) which may be pushed in to operate an alarm - for example a fire alarm. Instead of being made wholly of glass or other frangible material as formerly, the front plate is effective to break a frangible area (105) against a stop (104). The frangible area is one of several, so that the switch may be reset by moving the stop relative to the frangible areas so that it cooperates with another when one frangible area has been broken. |
