The manual clamping device is a crane safety device which prevents outdoor cranes from sliding along the track along the track. A clamp that is normally attached to the structure of the crane's bottom is used to clamp the two sides of the track head to prevent sliding. Split moving and electrodynamic type two kinds. The manual clamping device is generally a screw type and simple structure, but the clamping force is small and slow, mainly used in small and small or temporary purpose cranes. Large crane or port crane mainly USES electric clamp rail. It is made by a heavy hammer through a lever or by a spring force to tighten the clamping track, and the cylinder force from the hydraulic system loosens the clamp. There are many types of manual clamping device, which can be divided into two kinds: manual vertical screw clamp rail and manual horizontal screw rail. The manual clamping device has the advantages of simple structure, compact structure, low cost and convenient operation, but the clamping force is limited, the action is slow and the safety is poor, which only applies to the small and medium-sized cranes. The model has sdj-i, which is 700mm in height and 500mm in width. The manual clamping device sdj-ii has a height of 900mm and a width of 500mm. There are also sdj-iii and sdj-0 manual clamping device.