WIRE ROPE SLING RESOURCES
Cable-Laid vs. Braided Slings
Wire Rope Slings
CABLE-LAID WIRE ROPE SLINGS
Cable-Laid Slings are fabricated from a machine made rope comprised of seven small wire ropes. The cable-laid body is typically 7x7x7, 7x7x19, or 7x6x19 Classification IWRC. This construction makes for a pliable rope and sling. These slings are used where flexibility and resistance to kinking and setting are more important than resistance to abrasion. Since the rope is made up of many smaller wire ropes, the slings can bend around smaller diameters without taking a permanent set or a kink. The many small wires are susceptible to abrasion.
The rated capacity adjustment Table 1 for choker hitches applies to cable-laid slings as well. Note the difference in the efficiency factor for calculating vertical choker hitch rated capacities.
Rated capacity for a basket hitch is based on a D/d ratio of 10, where “d” is the diameter of the cable-laid fabric. Tolerances and minimum sling lengths are also figured using the cable-laid fabric diameter.
BRAIDED MULTI-PART SLINGS
Multi-part braided slings or Multi-Parts as they are known, are generally hand fabricated slings which are “braided” from 2, 3, 4 and up to as many as 48 pieces or parts of rope. Generally 4, 6, 8 & 9 parts are the more common. They can be either flat or round and offer the ultimate in flexibility and versatility. These are truly the heavy weights of the lifting industry. This book covers only the round type slings. They snug up tightly to the load in a choker hitch and resist kinking and setting. Loads in excess of 4000 tons have been lifted with multi-part slings.
Nominal Splice Efficiency for multi-part slings is 0.70 for component ropes 3/32” through 2” diameters. For larger component rope slings, consult the sling manufacturer for splice efficiencies.
Because of the multi-rope component construction, multi-part slings react differently than standard wire rope slings in a choker hitch therefore the nominal splice efficiency is present in the equation. The adjustment Table 1 applies to multi-part slings also.
Rated Capacity for a basket hitch is based on a minimum D/d ratio of 25, where “d” = component rope diameter.
Length tolerances for component ropes of 3/8” diameter and smaller are plus or minus 10 component rope diameters, or plus or minus 1.5% of the sling length whichever is greater. The legs of matched slings shall be within 5 component rope diameters of each other. For component rope diameters 7/16” and larger, the tolerance is plus or minus 6 component rope diameters, or plus or minus 1% of the sling length whichever is the greater. Legs of matched slings shall be within 3 component rope diameters of each other.
Minimum Sling Length between loops, sockets or sleeves is recommended to be 40 times the component rope diameter of the braided body.