Bimetal thermometers are thermometers based on the functional principle that metals expand differently depending on the change in temperature. A bimetal thermometer always consists of two different metal strips that have a different thermal expansion coefficient. The two strips are joined together inseparably and thus form the bimetal strip. When the temperature changes, the different metals expand to different degrees, which leads to a mechanical deformation of the bimetal strip. This mechanical deformation can be detected in a rotary movement. The measuring system works in the form of a helical or spiral tube. This movement is transmitted to the pointer of the thermometer via the pointer shaft, which thus enables the temperature to be measured.