Quick unloading valve is a key protective device used for emergency shutdown in industrial equipment such as steam turbines. This device is designed with mechanical hydraulic interlocking, which can quickly release the high-pressure oil in the lower chamber of the hydraulic motor piston when detecting system faults (such as abnormal oil pressure, unit overspeed) or emergency cut-off oil pressure loss, causing the valve to rigidly close under the action of spring force . Its action process is not affected by the electrical control system and can serve as the last physical barrier for equipment safety protection , effectively preventing major accidents such as turbine runaway. It is at the core of safety protection in EH high-pressure fire-resistant oil systems .