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Every
Lift Uses 1 of 3 Basic Hitches
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| Sling
angles have a direct and oftentimes dramatic affect
on the rated capacity of a sling. This
angle, which is measured between a horizontal line
and the sling leg or body, may apply to a single leg
sling in an angled vertical or basket hitch, or to
a multi-legged bridle sling. Anytime pull is exerted
at an angle on a leg, the tension or stress on each
leg is increased. To illustrate, each sling leg in
a vertical basket hitch absorbs 500 lbs. of stress
from a 1,000 lb. load. The same load, when lifted
in a 60 degree basket hitch, exerts 577 lbs. of tension
on each leg. |
| It
is critical therefore, that rated capacities be reduced
to account for sling angles. Angles less than 45 degrees
are not recommended and those below 30 degrees should
be avoided whenever possible. Use the formula and
chart shown below to calculate the reduction in rated
capacities caused by various sling angles. |
| Actual
Sling Capacity = Factor x Rated Capacity

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- Rated
capacity of a wire rope sling is based upon the nominal or catalog
strength of the wire rope and factors affecting the overall
strength. These factors include termination efficiencies (see
chart), type of hitch, number of rope parts in the sling body,
diameter around which the sling is bent, and diameter of the
pin or hook over which the sling eye is placed.
- Never
force the eye of a sling onto a hook or pin that has a diameter
larger than the natural width of the eye. Also avoid placing
a sling eye onto a hook or pin whose diameter is less than the
diameter of the sling body.
- Rated
capacities of fittings and attachments must be equal to or greater
than that of the wire rope sling.
- Never
"shock load" a sling. The actual force caused by a
sudden application of load can easily exceed rated capacities
and damage a sling. Abruptly releasing a load can also damage
the sling.
- Protect
the sling body against sharp edges and corners of loads, protrusions
or abrasive surfaces. Sharp bends can distort wire rope and
reduce its strength.
- Fiber
core wire rope slings should never be exposed to temperatures
exceeding 200 degrees F. Avoid using IWRC wire rope slings at
temperatures above 400 degrees F or below -60 degrees F.
- Slings
are susceptible to damage and strength loss when used in chemically
active environments.
- Slings
fabricated with a hand tucked splice can unravel and fail if
the sling is allowed to rotate during use.
- Do
not drag slings across floors or pull from underneath loads.
- Avoid
twists, kinks and knots before lifting.
- Store
wire rope slings where they will not be subjected to dirt, moisture,
extreme heat, corrosion or mechanical damage.
|
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Wire
Rope Socket
Poured Spelter or Resin |
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|
Mechanical
Splice
Loop or Thimble |
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| Loop
or Thimble Splice Hand Tucked |
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