| 摘要 |
<p>The earthquake alarm comprises a box housing made of insulating material (2) containing an electric bell or gong powered by four dry cells (14a-d). The gong is operated by a plunger (9, 10) attached to a spring-loaded solenoid armature (13). The coil of the solenoid is in series with the cells and a switch actuated by a pendulum and mercury switch (24). The pendulum comprises a ball chain (17a) hung from a bracket (16) and which passes through a ring contact (19). The lower end of the chain is weighted by a lead ball (18). The disturbance of the weighted chain due to seismic shock causes it to contact the ring switch and complete the electrical circuit. The mercury switch, which is operated by the movement of the spring-loaded armature, acts as an interrupter for the bell.</p> |
