Ground-frost detector for automobiles - uses expansion of frozen water in tube to close alarm contacts

摘要

The ground frost detector has a casing(1) enclosing a contactor, a tube(2) containing water(1) and an expansion ring(3). A reset spring(7) is controlled by the tube(2) via a contact tube(9) which is stiffer than a spring contact(5). The casing(1)encloses contact springs(5, 6) and a fixing ball(8). The detector is placed on the outside of the vehicle at the lowest point possible. When the temperature is low enough to freeze the water in the tube it expands linearly to close the contacts(5, 6). the contacts are connected to an alarm circuit inside the vehicle.