Rotation-resistant ropes can frequently provide
the best and most economical service in specific
applications when you choose, handle and use them
properly.
Contra-helically laid, rotation-resistant ropes
are different from standard ropes because they're
designed to reduce rope torque. Modes of failure
and wear for rotation-resistant ropes can differ
from those for standard rope constructions. The
very nature of these ropes requires special handling,
selection and usage not encountered with standard
constructions. They are susceptible to kinking,
crushing and unbalancing in the form of "core
pops" and "birdcages." Use extreme
care to avoid operational practices that can possibly
lead to these conditions.
There are different types of rotation-resistant
ropes, categorized by their resistance to rotation.
Category 1 rotation-resistant rope has at least
15 outer strands, has three layers of strands
(over a center) and has little or no tendency
to rotate, or, if guided, transmits little or
no torque. Category 2 rotation-resistant rope
has 10 or more outer strands, has two or more
layers of strands (over a center) and has significant
resistance to rotation. Category 3 rotation-resistant
has no more than 9 outer strands, has two layers
of strands (over a center) and has limited resistance
to rotation. For best performance, Category 2
and 3 rotation-resistant ropes should not be used
with a swivel. Category 1 rotation-resistant rope
may be used with a swivel.
Rotation-resistant ropes should be replaced when
you see two randomly distributed crown wire breaks
in six rope diameters -- or four randomly distributed
crown wire breaks in 30 rope diameters. If any
significant reduction in diameter is found in
a short length of a rotation-resistant rope, the
rope needs to be replaced.
Because rotation-resistant ropes are special,
there are separate design, maintenance, inspection
and removal criteria established for them by applicable
industry regulations and standards.
We recommend that rotation-resistant ropes be
used with a minimum design factor of 5.0.
Flex-X® 35
Tower crane and other long fall hoisting applications
require superior rotation resistance and minimum
torque—qualities you will find with the
latest addition to our family of rotation resistant
wire rope, Flex-X 35. It is a Category 1 rotation
resistant rope.
Flex-X 35’s unique design minimizes load-induced
torque and rotation of the rope. It is engineered
to give you maximum strength per diameter while
providing superior fatigue resistance. Flex-X
35 also assists you in maintaining proper load
control in single-part hoisting or in multi-part
hoisting where block rotation is a problem.
Flex-X 35 wire rope has one of the highest strength-to-diameter
ratios on the market. ASME B30.5 Mobile and Locomotive
Cranes require a design factor of 3.5 for 6-strand
hoist ropes. The same standard requires a design
factor of 5.0 for rotation resistant ropes. This
means that using rotation resistant ropes frequently
reduces the lifting capabilities of your crane
due to the higher design factor.
Flex-X 35 eliminates this reduction. The Minimum
Breaking Force (MBF) of Flex-X 35 is such that
even with the 5.0 design factor, it has lifting
capacities that equal or exceed 6-strand XIP ropes
utilizing a 3.5 design factor. Other ropes of
similar grade and construction do not provide
this benefit.
The
multi-strand design of Flex-X 35 combined with
compacted strands and lang lay construction helps
to maximize resistance to wear by greatly increasing
wire and strand surface areas that contact sheaves
and drums. Internally, the enhanced surfaces of
the compacted strands help minimize strand-to-strand
nicking between strand layers that occurs in other
rotation resistant ropes. This feature results
in greater resistance to fatigue.
The
characteristics of Flex-X 35 enhance its performance
in multiple-layer spooling as well. The lang lay
design coupled with the special Flex-X features
provides excellent resistance to abrasion that
occurs at kickover areas in drum spooling. The
rope construction combined with the compacted
strand design of Flex-X 35 results in a rope cross-section
of very high density. This feature provides increased
resistance to crushing.
Flex-X 35 Flyer (right click to save)
|
|
Flex-x® 35 Minimum Breaking
Force and Weights |
| Diameter
(mm) |
Approx.
wt./ft.
(lbs.) |
Minimum Breaking Force
(tons of 2000 lbs.) |
| 13 |
0.60 |
20.4 |
| *16 |
0.90 |
30.6 |
| 18 |
1.2 |
38.5 |
| *19 |
1.3 |
42.9 |
| 22 |
1.7 |
57.2 |
| *25.4 |
2.2 |
75.8 |
| 26 |
2.3 |
79.3 |
| 28 |
2.7 |
91.6 |
| *30 |
3.1 |
105 |
| 32 |
3.5 |
119 |
|
|
|
|
*
Standard Inventory Items
Flex-X® 19
Flex-X 19 is made from 19 strands and is a category
2 rotation resistant rope. Six strands are laid
around a core strand in one direction, then 12
Strands are laid around this first operation in
the opposite direction. Because of its tightly
compacted, smooth design, Flex-X 19 offers advantages:
- More crush resistance than a
standard 19x 7 rope while providing the same
rotation resistance.
- Higher strength-to-diameter
due to compacted wires in the strands. With
increased metallic area, it provides rope strengths
equal to 6 strand XXIP IWRC ropes of the same
diameter.
- Resistance to bending fatigue
due to the uniformity of the wires within each
strand. The strand's outer surface is smooth,
reducing contact pressures between the rope's
strands and radial pressures as it operates
over sheaves and drums.
- Exceptional stability due to
the higher density strands coupled with the
smooth outer surface.
- Improved handling, operating
and spooling characteristics.
- Reduced wear to sheaves and
drums.
It's used in single-part or multi-part hoist
lines wherever you encounter spooling problems,
drum crushing, block twisting or have fast line
speeds.
Flex-X 19 (right click to save)
19 x7
rope
A 19X7 is made from 19 strands and is a category
2 rotation resistant rope. It is used where resistant
properties are essential for rope performance.
Its rotation-resistant characteristic is achieved
by laying six strands around a core strand in
one direction, then laying 12 strands around the
first operation in the opposite direction. Thus,
when the rope is in tension, opposing rotational
forces are created between the inner and outer
layers.
While having similar rotation resistance to a
Flex-X 19, a 19X7 has a lower strength, will crush
easier and is not as fatigue or wear resistant.
8 x 25
Resistwist® rope
In a multi-part wire rope system where the blocks
have a tendency to twist -- the 8 x 25 Resistwist
rope has found successful application. It is a
category 3 rotation resistant rope. The rotation-resistant
characteristic is achieved by laying the eight
outer strands around an independent wire rope
core so these strands are in the opposite direction
to the lay of the core. Thus, when the rope is
in tension, opposing rotational forces are created
between the core and the outer strands.
Though not as rotation-resistant, the 8 x 25
Resistwist is more stable than a 19 x 7 rope.
It also has increased resistance to bending fatigue
and crushing. This is achieved through the use
of eight-strand construction with an independent
wire rope core.
|
|
Flex-x® 19 |
19 x 7 XIP® |
8 x 25 XIP® |
| Diameter
(in.) |
Approx.
wt./ft.
(lbs.) |
Minimum Breaking Force
(tons of 2000 lbs.)* |
Approx.
wt./ft.
(lbs.) |
Minimum Breaking Force
(tons of 2000 lbs.)* |
Approx.
wt./ft.
(lbs.) |
Minimum Breaking Force
(tons of 2000 lbs.)* |
| 3/16 |
-- |
-- |
0.064 |
1.57 |
-- |
-- |
| 1/4 |
-- |
-- |
0.133 |
2.77 |
-- |
-- |
| 5/16 |
-- |
-- |
.0177 |
4.30 |
0.18 |
4.63 |
| 3/8 |
0.31 |
8.3 |
0.25 |
6.15 |
0.26 |
6.63 |
| 7-16 |
0.40 |
11.2 |
0.35 |
8.33 |
0.36 |
8.97 |
| 1/2 |
0.54 |
14.6 |
0.45 |
10.8 |
0.47 |
11.6 |
| 9/16 |
0.69 |
18.5 |
0.58 |
13.6 |
0.60 |
14.7 |
| 5/8 |
0.85 |
22.7 |
0.71 |
16.8 |
0.73 |
18.1 |
| 3/4 |
1.25 |
32.4 |
1.02 |
24.0 |
1.06 |
25.9 |
| 7/8 |
1.68 |
43.8 |
1.39 |
32.5 |
1.44 |
35.0 |
| 1 |
2.17 |
56.9 |
1.82 |
42.2 |
1.88 |
45.5 |
| 1
1/8 |
2.75 |
71.5 |
2.30 |
53.1 |
2.39 |
57.3 |
| 1
1/4 |
3.45 |
87.9 |
2.83 |
65.1 |
2.94 |
70.5 |
| 1
3/8 |
4.33 |
106 |
3.43 |
78.4 |
3.56 |
84.9 |
| 1
1/2 |
5.11 |
125 |
4.08 |
92.8 |
4.24 |
100 |
*
These strengths apply only when a test is conducted
with both ends fixed. When in
use,
the strengths of these ropes may be significantly
reduced if one end is free to
rotate
