Disconnect
The switch shown to the right is intended to disable an electric fuel pump in automotive applications. This functionality is required in some vehicle racing applications, since an electric fuel pump may otherwise continue operating after a collision or rollover. If the fuel line is broken or the vehicle is inverted, fuel may be spilled, creating a fire hazard. A small loose weight (called a proof mass) is trapped within a spring-loaded cage. A shock in any direction will cause movement of the mass relative to the cage, and if sufficiently shocked the cage will spring open, actuating an associated switch. The switch is reset by pressing the cage closed through the flexible (red) top cover, retrapping the mass. These switches are also used to open a contactor (a large relay) to disable the high power circuit of a battery electric vehicle upon collision.
Read more about this topic: Inertial Switch