Electric hoist is a special hoisting equipment installed on overhead crane and gantry crane. It has the characteristics of small size, light weight, simple operation and convenient use. It is used in industrial and mining enterprises, storage docks and other places. The lifting weight is generally 0.1 to 80 tons, and the lifting height is 3 to 30 meters. It is composed of electric motor, transmission mechanism and reel or sprocket, which are mainly divided into two types: wire rope electric hoist and ring chain electric hoist.