SLINGS

WIRE ROPE

GENERAL INFORMATION 

This D/d ratio is applied to wire rope slings to assure that

the strength in the body of the sling is at least equal to the

splice efficiency.  When D/d ratios smaller than those listed

in the rated capacity tables are necessary, the rated

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capacity of the sling must be decreased.

RATED CAPACITY is the maximum static load a sling is

designed to lift.  The tables give rated capacities in tons of

2000 pounds.  Rated capacities contained in all the tables

were calculated by computer.  Each value was calculated

starting with the nominal component rope strength and

working up from there.  Due to computer rounding of

Figure 7.

numeric values, rated capacity values for 2, 3 or 4 leg

slings may not be even multiples of single leg values and

PROOF LOAD is a specific load applied o a sling or

may differ by a small amount.  This represents the state 

assembly in a non destructive test to verify the workman 

of the art technology and tables found in other publications

ship of the sling.  All swaged socket or poured socket

which differ by this small amount should not be construed

assemblies should be proof loaded.  The proof load is gen 

to be in error.  The difference is generally no more than

erally two (2) times the vertical rated capacity for mechani 

one unit for any sling diameter.

cal splice slings.  The maximum proof load for hand tucked

slings is 1.25 times the vertical rated capacity.  Care

When a wire rope is bent around any sheave or other cir 

should be taken to assure that sling eyes are not damaged

cular object, there is a loss of strength due to this bending

during the proof load.

action.  As the D/d ratio becomes smaller this loss of

EYE DIMENSIONS are generally eight (8) sling body

diameters wide by sixteen (16) body diameters long.

Whenever possible thimbles are recommended to protect

the rope in the sling eye.  Eye dimensions for thimbles are

contained in table 2.  Table 2 contains only dimensions for

thimbles used in standard single part slings.  Other spe 

cialized thimbles are available.  Consult your sling manu 

facturer for details.

PIN DIAMETER should not be any greater than the natural

width of the sling eye.  For any sized eye and type of sling

body, the maximum allowable pin diameter may be calcu 

Figure 5.

lated as follows.

strength becomes greater and the rope becomes less effi 

Maximum pin diameter = (2L + W) x 0.2

cient.  This curve, derived from actual test data, relates the

Where 

efficiency of a rope to different D/d ratios.  This curve is

L = length of eye

based on static loads only and applies to 6X19 and 6X37

W = width of eye

class ropes.

The minimum pin diameter should never be smaller than

the nominal sling diameter.

GRADE & CONSTRUCTION of wire rope for slings is gen 

erally accepted to be bright Improved Plow Steel or Extra

Improved Plow Steel grade 6x19 or 6x37 classification reg 

ular lay.  IWRC rope has a higher rated capacity than Fiber

Core rope for mechanically spliced slings, but the same

rated capacity for hand tucked slings.  This is because

when making a hand tucked splice, the core (IWRC) of the

Figure 6.

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