Interceptor actuated by seismic vibrations

Apparatus actuated by seismic vibration comprising a housing, a rod extending vertically through said housing and being vertically movable between upper and lower positions, a spring means acting on said rod for biassing the rod downwardly, a ball mounted on said rod, a keeper member including a central portion rockably engaged with the ball and an outer projecting portion with a step therein, a plurality of stays pivotably mounted in said housing and disposed around said rod for undergoing inclination relative to the rod, said stays having upper ends engaged in the step of the keeper member to support the rod in the upper position, tension springs mounted on upper portions of the stays and biassing each stay toward the rod, a weight support member fixed to the lower portion of the rod, a first weight having a bore through which the rod passes, said weight being rockably supported by the weight support member and having an outer portion resting on said stays to be horizontally maintained thereby, said stays being pivotable outwardly away from the rod by said weight for releasing the engagement of the stays with the keeper member to permit the rod to drop downwardly, and a second weight having a bore through which the rod passes, said second weight being slidably mounted on the first weight so that during vibration it can travel laterally and apply force to said first weight and thereby to said stays to pivot the same away from the rod.