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.”

Chain Size
9/32"	3,500	3,500	4,900	6,100	5,200	7,400	9,100
3/8"	7,100	7,100	10,000	12,300	10,600	15,100	18,400
1/2"	12,000	12,000	17,000	20,800	18,000	25,500	31,200
5/8"	18,100	18,100	25,600	31,300	27,100	38,400	47,000
3/4"	28,300	28,300	40,000	49,000	42,400	60,000	73,500
7/8"	34,200	34,200	48,400	59,200	51,300	72,500	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.

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