Length
Tolerances (Single Part Wire Rope Slings): Standard length tolerance
is plus or minus two rope diameters,
OR plus or minus 0.5% of the sling length, whichever is greater.
The legs of bridle slings, or matched slings are
normally held to within one rope diameter.
Other
fittings and latches are available upon request.
¹Minimum
length based on thimbled eye and eye hook.
*
Do
not exceed rated capacities. Sling capacity decreases as the
angle from horizontal decreases.
Slings should not be used at angles of less than 30°. Refer
to the effect of Angle chart below..
EFFECT
OF SLING ANGLE
Using
slings at an angle can become deadly if that angle is
not taken into consideration when selecting the sling to
be used. The tension on each leg of the sling is increased as
the angle of lift, from horizontal, decreases. It is most
desirable for a sling to have a larger angle of lift, approaching
90°. Lifts with angles of less than 30° from horizontal
are not recommended. If you can measure the angle of lift or
the length and height of the sling as rigged, you can
determine the properly rated sling for your lift. The Increased
Tension method provides the increased tension as a
function of the sling angle. Alternatively, the sling Reduced
Capacity method may be used to determine reduced lift
capacity for any angle.
INCREASED
TENSION
Determine capacity
of sling needed
REDUCED
CAPACITY Calculate rating of each
sling
rigged at this angle
1.
Determine the load weight (LW).
1.
Calculate the reduction factor (RF).
a.
Using the angle from horizontal,
read across the Angle Chart to
the corresponding number of the
Reduction Factor column.
2.
Calculate the Tension Factor [TF].
a.
Determine the sling angle as mea-
sured from the horizontal, and the
corresponding tension factor (TF)
from the effect of angle chart.
-OR-
b.
Divide sling height* (H) by sling
length* (L).
-OR-
b.
Length* (L) divided by height*
(H)
2.
Reduction factor (RF) x the sling’s
rated capacity for the type hitch that
will be used = sling’s reduced rating.
3.
Determine the share of the load
applied to each sling leg (LW).
4.
Multiply (LW) by (TF) to determine
the sling leg tension. The capacity of
the selected sling or sling leg must
meet the calculated tension value.
*Measured
from a common horizontal
plane to the hoisting hook.
*Measured
from a common horizontal plane
to the hoisting hook.
Effect
of Angle Chart
Tension
Factor (TF)
Angle From
Horizontal
Reduction
Factor (RF)
1.000
90º
1.000
1.004
85º
0.996
1.015
80º
0.985
1.035
75º
0.966
1.064
70º
0.940
1.104
65º
0.906
1.155
60º
0.866
1.221
55º
0.819
1.305
50º
0.766
1.414
45º
0.707
1.555
40º
0.643
1.742
35º
0.574
2.000
30º
0.500
Example:
Vertical
Choker rating of each sling:
6,000 lbs.
Measured Length (L) = 6 ft.
Measured Height (H) = 4 ft.
Reduction Factor (RF) = 4 (H) ÷ 6 (L) = .667
Example:
Load
weight = 1,000 lbs.
Rigging - 2 slings in vertical hitch
Lifting Weight (LW) per sling = 500 lbs.
Measured Length (L) = 10 ft.
Measured Height (H) = 5 ft.
Tension Factor (TF) = 10 (L) ÷ 5 (H) = 2.0
Minimum Vertical Rated Capacity required
for this lift = 500 (LW) x 2.0 (TF) = 1000 lbs.
per sling
Sling
capacity decreases as the angle
from horizontal decreases. Sling angles
of less than 30° are not recommended.
Reduced
sling rating in this configuration
= .667
(RF)
x 6,000 lbs. = 4,000 lbs. of lifting
capacity per sling
Wire Rope Bridle
Slings, 2, 3, & 4 Leg, Wire Rope Sling, Lift-All, Lifting
Slings, 2-Leg Bridle Sling, Prices include
Thimbled Eyes and Eye Hooks, 3-Leg Bridle Sling, and 4-Leg
Bridle Sling from your source for material handling
equipment.
Thimble eyes protect wire rope from
