a lifting hook for lifting open - frame steel joists comprises a casing having a shaft passing through it . the shaft has a lifting eye at one end and a hook member at the other end . the hook member comprises a u - shaped body having a transverse width selected to be less than the gap between the angles that form the upper flange of the open - frame joist . the hook member has a throat that is larger than the width of the flange . the shaft is spring - loaded so that the hook member is pulled toward the lower bearing surface of the casing so that once the hook member has been inserted into the joist , it is keyed to the flange and will not come loose .