Torque limiters, also called overload clutches, are used to prevent mechanical overload. The most common torque limiters are friction-style slip clutches and shear pins. Friction-style slip clutches automatically allow the load to slip to prevent overloading. They wear over time and require occasional maintenance. Shear pins prevent overloading through shearing, which disconnects the load. Shear pins must be replaced after each overload. Both friction-type torque limiters and shear pin hubs are often used with matching sprockets to further protect against overload. Replacing worn friction faces, rotor seals, or quills can also improve performance.