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

working-load-01

 

Chain Size

working-load-limits-90working-load-limits-30-45-60working-load-limits-30-45-60

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
12,000
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
60,000
72,500

9,100
18,400
31,200
47,000
73,500
88,900

 

 

EFFECT OF ANGLES ON SLING CAPACITIES

effect-sling-cap

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 ANGLELOAD 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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