当加热时，本体内的蜡膨胀，胶管受蜡挤压，推动推杆向上运动，产生升程和推动力当冷却时，弹簧推动推杆回位。
When heated, the wax in the cup expands and the pressure applies, via the sleeve, both a radial force and an axial force on the piston.Again, an external spring ensures the return of the piston when the temperature decreases.
