The basic functional principle of dry friction torque limiter is to protect the mechanical parts in the transmission equipment with overload through its simple structure and easy maintenance. Is different from the power of the electric protection, mechanical protection is based on any rotating object itself with the principle of moment of inertia, namely "flywheel effect", the release of energy generated in a speed reduced or consumption, through the mechanical way transformation, thus to protect equipment from damage impact loading, to ensure that the service life and security equipment operation.