The commonly used chain grab is arranged with three chains, which are the main chain with one end fixed on the main sprocket of the lower bearing beam, and two branch chains with two ends fixed on the side of the upper bearing beam and the main shaft of the lower bearing beam. By lifting the main chain, let the main sprocket turn, thereby driving the lower beam spindle rotation. The two branch chains fixed between the upper and lower bearing beams are wound on the main shaft of the lower bearing beam, and the distance between the upper and lower bearing beams is shortened by winding to realize the closure of the grab bucket.

Chain grab is commonly used in ocean, inland river, port, dock desilting, sludge cleaning and salvage and other difficult working environment. The chain grab can achieve dredging, dredging, cleaning and other operations in a more harsh environment, with high efficiency, simple maintenance and low use cost.
The double rope chain grab is suitable for cranes of 8~16 tons.