Angle of hoisting affects a sling load limit:
Stresses are minimal for loads with slings held perpendicular to the load, as shown in Figure A. For distributing the load vertically on more than one leg of a sling, a spreader bar may be used. As shown in figures B-D, increasing the angle of the sling to the hook from 30 to 60 degrees increases the effective mass of the load from 1154 lbs. to 2000 lbs., basically doubling the weight of the sling at 60 degrees. The chart offers a guide for assessing the effective angle of the sling to the relative weight. Thus, it is always better to limit the angle of the sling. Changes in sling angle must be accounted for in lifts that are close to the sling weight limit and/or for critical lifts (greater than 90% of the crane limit).