In electrical engineering a limit switch is a switch operated by the motion of a machine part or presence of an object. They are used for control of a machine, as safety interlocks, or to count objects passing a point. A limit switch is an electromechanical device that consists of an actuator mechanically linked to a set of contacts. When an objec... Found on http://en.wikipedia.org/wiki/Limit_switch
A safety control that automatically shuts off a furnace if it gets too hot. Most also control blower cycles. Found on http://www.encyclo.co.uk/local/20933
A protective device used to open or close electrical circuits when certain limits, such as temperature or pressure, are reached. Found on http://www.youngco.com/young2.asp?ID=4&Type=3