Abstract A new type of circular friction device, applied in gate operating mechanism of water turbine to provide overload protection for guide vane, is presented. It adopts a new preload structure (FROMO® preloadnut). Through compare with structures of break pin protection device and end plane protection device and analysis of experimental data, the results indicate that this device is simple and convenient in setting friction torque, which has good consistency and accuracy , and makes the mechanism have good performance of reapplication.
