in machine building, a part of load-lifting machines that suspends loads or lifting attachments on the cables or chains of hoisting mechanisms (load hook); a part of transport machines that transmits tractive forces (coupling hook, draw hook), as between a tractor and trailer. Hooks are made as single hooks or double (sister) hooks. Load hooks made of cast or unit-forged steel have load-lifting capacities of up to 75 tons; laminated load hooks made of drop-forged steel plates have load-lifting capaci-ties of more than 75 tons. Coupling hooks are usually forged or cast single hooks. The main characteristics of hooks are standardized.