Working Load Limits

Numerical values published for Breaking Strength and Working Load Limit are very specific in one point:

• They refer to straight, in-line pull or force and are obtained under laboratory conditions.
• There are, however, many applications where a straight line pull is not possible or even desirable. When a tackle block system is reeved, wire rope may be bent over many sheaves; multiple leg wire rope or chain slings involve differing lifting angles; angular loads on shackles or eyebolts alter Working Load Limits of the equipment used.
• Ail these and other factors influencing the Working Load Limit must be taken into account when systems are designed and used.
• The following examples and tables are intended to highlight and demonstrate the effects of angles on the Working Load Limit.

CHAIN SLINGS, Fabricated entirely from grade 80 alloy components.”

WORKING LOAD LIMITS – POUNDS

 

Chain Size
9/32” 3/8” 1/2” 5/8” 3/4” 7/8”	3,500 7,100 12,000 18,100 28,300 34,200	3,500 7,100 7,100 18,100 28,300 34,200	4,900 10,000 17,000 25,600 40,000 48,400	6,100 12,300 20,800 31,300 49,000 59,200	5,200 10,600 18,000 27,100 42,400 51,300	7,400 15,100 25,500 38,400 38,400 72,500	9,100 18,400 31,200 47,000 73,500 88,900

 

 

EFFECT OF ANGLES ON SLING CAPACITIES

The rated capacity of a multiple leg sling is directly affected by the angle of the sling leg with the load. As this angle decreases, the stress on each leg increases with the same load. If the sling angle is known, the capacity can be readily determined by multiplying the sling’s vertical capacity by the appropriate load angle factor from the table at right.

SLING ANGLE LOAD ANGLE FACTOR 90° (vertical) 1.000 75° .966 60° .866 45° .707 30° .500 15° .259

Example: A multiple leg sling with a rated capacity of 2000 lb. Will have a reduced capacity of 1000 lb. (2000 x.500) when sling legs are at an angle of 30° with the load.