When crane electrical control part revision, its content includes the original GB3811-1983, FEM the relevant part of the content, at the same time increase the frequency control of motor speed and pressure regulating speed. (to hook crane, when lifting mechanism work level for the M4, M5, and M6, and rated lifting speed 5 m/min or more smooth braking, electric braking method should be adopted, and ensure that fell within the range of 0.2 ~ 1.0 G before the brake motor droop below 1/3 of the synchronous speed, the speed should be able to stable operation.)