Mercury switch

When the switch is tilted in the appropriate direction, the mercury touches a set of contacts, thus completing an electrical circuit.

Tilting the switch in the opposite direction moves the mercury away from that set of contacts, breaking that circuit.

There are several non-mercury types, but few are implemented due to sensitivity to shock and vibration, causing false tripping.

[6][7] While doing more researches in the 1950s, Austrian bellfounder from Vienna, Josef Pfundner jr., decided to develop a newer way to electrify church bells.

Some electrificators in Croatia also adopted this system, like Alojz Domislović, his successor Luka Ivandija, and a bit later Ivan Bosilj.

Electrically driven attitude indicators typically use mercury switches to keep the gyro axis vertical.

The bimetal spring had to move further to overcome the weight of the mercury, tending to hold it in the open or closed position.

The mercury also provided positive on-off switching, and could withstand millions of cycles without contact degradation.

[8][9] Mercury tilt switches can be found in some bomb and landmine fuzes, typically in the form of anti-handling devices, for example, a variant of the VS-50 mine.

A metal ball and contact wires can directly replace it, but may require additional circuitry to eliminate switch bounce.

In the United States, the Environmental Protection Agency (EPA) regulates the disposition and release of mercury.