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SLINGS
WIRE ROPE
GENERAL INFORMATION
Length tolerances or poured attachments can be some
type slings. They snug up tightly to the load in a choker
what more stringent than other types of slings. The manu
hitch and resist kinking and setting. Loads in excess of
facturer should be contacted and agreement reached
4000 tons have been lifted with multi part slings.
before the order is placed. Tolerance as small as plus or
3
minus 1/8 is not out of the ordinary for this type of assem
Nominal Splice Efficiency for multi part slings is 0.70 for
bly. Specifications such as type of fitting, pin orientation,
component rope 3/32 through 2 diameters. For larger
whether zinc or resin is to be used and type of application
component rope slings, consult the sling manufacturer for
should also be supplied to the manufacturer when ordering
splice efficiencies.
these types of assemblies. Those inexperienced in the
socketing process should not try to fabricate assemblies
Because of the multi rope component construction, multi
without first getting expert training. It is far better to leave
part slings react differently than standard wire rope slings
fabrication of this type of assembly to the experts. The fol
in a choker hitch therefore the nominal splice efficiency is
lowing socketing methods are general in nature and have
present in the equation. The adjustment Table 1 applies to
withstood the test of time. Slight variations to these
multi part slings also.
methods will produce equal results.
Rated capacity for a basket hitch is based on a minimum
The two procedures, while achieving the same end result,
D/d ratio of 25, where d =component rope diameter.
differ significantly. It is highly recommended that all
poured sockets whether they be zinc or resin, be proof
Length tolerances for component ropes of 3/8 diameter
loaded.
and smaller are plus or minus 10 component rope diame
ters, or plus or minus 1.5% of the sling length whichever is
CABLE LAID WIRE ROPE SLINGS
greater. The legs of matched slings shall be within 5 com
Cable laid slings are fabricated from a machine made rope
ponent rope diameters of each other. For component rope
compromised of seven small wire ropes. The cable laid
diameters 7/16 and larger, the tolerance is plus or minus
body is typically 7x7x7, 7x7x19, 7x6x19, 7X6X36
6 component rope diameters, or plus or minus 1% of the
Classification IWRC. This construction makes for a pliable
sling length whichever is the greater. Legs of matches
rope and sling. These slings are used where flexibility and
slings shall be within 3 component rope diameters of each
resistance to kinking and setting are more important than
other. Minimum Sling Length between loops,
resistance to abrasion. Since the rope is made up of
sockets of sleeves is recommended to be 40 times the
many smaller wire ropes, the slings can bend around
component rope diameter of the braided body.
smaller diameters without taking a permanent set or a
kink. The many small wires are susceptible to abrasion.
GROMMETS
Grommets are a unique type of sling. They form a com
The rated capacity adjustment Table 1 for choker hitches
plete circle and automatically double the number of lifting
applies to cable laid slings as well. Note the difference in
legs. Several types are available, such as strand laid
the efficiency factor for calculating vertical choker hitch
hand tucked and cable laid mechanical. Grommets work
rated capacities.
well in basket and choker hitches and general applications
will find them used in this manner. Another unique advan
Rated capacity for a basket hitch is based on a D/d ratio of
tage to grommets is that the load contact points may be
10, where d is the diameter of the cable laid fabric.
rotated or moved around the sling to even out the wear
Tolerances and minimum sling lengths are also figured
points. The only area that should not come into contact
using the cable laid fabric diameter.
with the load is the splice area. The sling manufacturer
will usually mark the area of hand tucked grommets with
BRAIDED MULTI PART SLINGS
paint to help the user more easily identify the splice area.
Multi part braided slings or Multi parts as they are known,
are generally hand fabricated slings which are braided
Tolerances for grommets are generally plus or minus 1%
from 2,3,4 and up to as many as 48 pieces or parts of
of the circumferential length or 6 body diameters
rope. Generally 4,6,8&9 parts are the more common.
whichever is the greater.
They can be either flat or round and offer the ultimate in
flexibility and versatility. These are truly the heavy weights
A minimum circumference of 96 body diameters is recom
of the lifting industry. This book covers only the round
mended. This measurement is normally an inside circum
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