The chain hoists, lever hoist the effort principle, all with differential pulley; difference is the hand chain hoist with their bare hands to pull the chain to drive, more than used for vertical lifting heavy objects; lever hoist is used to move the handle way driver, used for horizontal move heavy objects. The principle of chain hoists: hand chain to drive the active pinion rotation, driven pinion gear rotation, will enlarge the torque output, thereby lifting heavy objects. A ratchet pawl body in the inside of the hand chain, so that the sprocket only one direction of rotation. The reason of the hand chain hoist is named because long like a gourd. Guangzhou gongyou lift slings machinery co.,ltd is a collective enterprise specializing in research, production and sales of lifting machine. It is a modern enterprise in manufacturing of chainblock ,electric hoist , lifting slings ,steel wire rope , rigging hardware and so on .