Principle structure of bimetal thermometer

The bimetallic thermometer uses a hot bimetallic piece wound into a threaded shape as a temperature sensing device, and it is installed in a protective sleeve. One end is fixed, called the fixed end, and the other end is connected to a thin shaft, called Free end. A pointer is provided on the free end spool. When the temperature changes, the free end of the temperature sensing device rotates accordingly, driving the pointer on the thin shaft to produce an angle change, and the corresponding temperature is indicated on the dial.