non rotation vs rotation resistant wire rope brands

Rotation resistant wire rope refers to a series of steel ropes which minimizes the tendency to spin or rotation under load. These wire ropes boast special design - the outer layer is twisted in the reverse direction of inner layers for counteracting torsional forces generated from multi-layers of strands.

To achieve the resistance against the spin and rotation, all wire ropes are composed of at least two layers of strands. In general, more layers a rotation resistant wire rope has, more resistance it will boast. For example, 2-layer ropes is much easier to spin and rotate than 3-layer ones. Meanwhile, if one end of free rotation is allowed, 2-layer rope can only develop 55% to 75% of its breaking strength comparing with 95% to 100% of 3-layer ropes.

The 3-layer rope with more outer strands is capable to distribute more radial pressure onto inner layers and ideal for larger mobile such as all tower cranes.

Wire ropes with 8 to 10 strands & 2-layer constructions without reversely twisted inner strands have very similar appearance to rotation resistant wire ropes, but they are not.

Rotation resistant wire ropes are considered to be less stable needing to be handled and installed with great care. They must be taken to avoid high loads with small diameter sheaves.

Rope Services Direct supplies a variety of anti-spin non rotating wire rope (also called rotation resistant wire-rope). All standard rope wirehas a tendency to develop torque and therefore prone to rotation, whereas non-rotating wire ropes are designed so that the wire-rope outer rotational force naturally counteracts the inner strands rotational force. This is in the event that a rope is subjected to a load.

Rope elongation and rotation occurs on standard ropes when loaded, which can therefore spin the load, quite possibly out of control, which can be dangerous. When the rope rotates in this way the strands will begin to unravel. This causes the rope to lose strength and will undoubtedly fail, which could be catastrophic. It is for these reasons that non rotating wire rope is commonly used for many types of lifting applications including main hoist rope, whip rope,crane rope, off-shore and deck rope and more.

Non rotating wire rope or rotation resistant wire rope has a different construction to standard. as wires and strands are not laid in the same direction like they would be on standard rope. Inner and outer strands of wires are laid in opposite directions. For example the inner may be constructed in left hand lay whilst the outer layer is in right hand lay. The nature of this construction means that torsional forces on the inner and outer wires/strands will counteract each other and therefore minimising the risk of unraveling.

It is worth noting that the number of strand layers will have an effect of the resistance of rotation. A 2 layer rope has less resistance than a 3 layer rope. Therefore the more layers the rope has the greater rotation resistance it will have.

These types of ropes can be classified as spin resistant, rotation resistant or non rotation resistant. Classed on the basis of the number of rotations a certain length of rope does when a force of 20% of the MBF is applied; with 1 turn or less the rope will be classified as non rotating; with rotations between 1 & 4 the rope is classed as low rotation and for rotations between 4 & 10 the rope will be classified as spin resistant, any higher and the rope is NOT rotation resistant at all.

Correct usage and care with handling will prolong the working life. This is due to the friction on the inner wires caused by the strand crossover’s which will eventually cause the inner wires to break up. This is more apparent on non rotating wire rope with two layers. Ropes with 3 or more strand layers will distribute the radial pressures more evenly. Which will reduce friction and stress on the inner wires.

Regular,thorough inspectionsof non rotating rope are essential due to the fact that it is the inner strands that often break first and broken internal wires often go unnoticed as they are difficult to see.Rope Services Direct offer inspectionson all rope with certification issued on completion.

Holding both ends of the rope will prevent unraveling. Correctly fitted terminations will help to prevent damage. Kinking and unraveling may occur and they can also have an effect on the rotational balance if not fitted correctly.

Rotation resistant wire rope is a special category (class) of wire rope designed to resist the tendency to spin or rotate under load. In general these ropes are used as single part lines, or in situations where operating conditions require a rope that will resist cabling in a multipart system. The essential nature of rotation resistant rope designs impose certain limitations on their application and necessitate special handling requirements not encountered with other rope constructions.

2) Multilayer strand (Multistrand)-consisting of two or more strand layers closed in opposing directions. Torsional forces generated by each layer of the rope counteract one another to minimize rotation.

The multistrand classification includes ropes with between eight and twenty outer strands. Table 1 of this manual describes some of the more commonly available rotation resistant multistrand rope classification. In addition to these, a wide variety of special multistrand ropes is available. See (Figure 9). It would be impractical to cover the specific features of each in this manual.

In multistrand rotation resistant ropes the crossover points between strand layers are points of high stress concentration. Relative motion of the strands at these points results in accelerated deterioration of the internal components of the rope. Because of this design characteristic of the multistrand construction, care must be taken to avoid high loads with small diameter sheaves. Design factors less than five are not recommended.

The most important factor in selecting the right wire rope for the job in hand is deciding whether a rope type is to be rotation resistant or non-rotation resistant. This point needs to be considered very carefully as using the wrong rope type can have serious consequences, for example, shortened service life, changes in the rope structure, unintentional rope breaks.

Rotation resistant ropes must be used for the lifting of an unguided load on a single fall,the lifting of an unguided load on several falls at a great lifting height

Non-rotation resistant ropesmust be used for the lifting of a guided load,the lifting of unguided loads on several falls at low lifting heights,the lifting of loads with right-handed and lefthanded ropes operating in pairs, Non-rotation resistant ropes must not be used with a swivel.

The characteristic of these wire ropesare that the outer layer is twisted in the opposite direction of their inner layers. The sometimes confusing issue is that many 8-, 9- and 10 strand constructions are 2-layer types but their inner strands are NOT twisted in the opposite direction and therefore these rope are NOT spin-resistant; plus, for the untrained eye these ropes look very much alike their spin-resistant variants. These and regular 6-strand ropes will spin violently and unlay themselves when loaded when one rope end is allowed to spin freely. They may also develop a significant drop in breaking strength and an even larger drop in their fatigue life characteristic (Torsion Fatigue).

To achieve any degree of resisting the tendency of a rope to spin and unlay under load all such rope types (other than 4-strand ones) are constructed with 2 or more layers of opposite twisted strands (see picture on right).

2-layer ropes (MULTI, compacted 18xk7) have a larger tendency to rotate than 3-layer ones (e.g. Class 34 x 7, compacted 35WXK7). Furthermore, 2-layer spin-resistant and rotation resistant ropes will develop only about 55% to 75% of their breaking strength when one end is allowed to rotate freely. This number increases to between 95% to 100% for 3-layer (e.g. 35WXK7 compacted) non-rotating ropes.

Another important issue is that 2-layer rotation resistant and 2-layer spin-resistant rope types have shown to break up from the inside. The 8 (e.g. 8×25 spin-resistant) or 12 outer strands (19×7, 19×19, 18XK7) are not able to evenly distribute the radial forces and because of the inherent internal strand cross overs (which make the rope spin- or rotation resistant) the resultant severe notching stresses cause the rope core to break up premature (unless the core is plastic coated). Unexpected and sudden rope failures may be the result. Moreover, 2-layer spin-resistant or rotation resistant ropes satisfy only low to moderate rotational resistance demands.

3-layer rope constructions (e.g. compacted 35WXK7) have many more outer strands which can much better distribute the radial pressures onto the reverse lay inner strands. These ropes should be selected for larger mobile- and ALL tower cranes.

Non-rotating (non-rotational) wire ropes are used in various on and offshore cranes, various machinery, winches and trolleys, in the maritime and fisheries sector, on and offshore oil exploitation, civil and industrial construction, engineering and infrastructure works, underground and surface mining, timber mining and numerous other industries and applications.

SWR supply a large range of non-rotating wire ropes in both galvanised and ungalvanised finish with either ordinary or langs lay. Depending upon your requirement for higher breaking load or better wear characteristics, these wire ropes are available in different finishes and lubrications as well as being available with plastic impregnated.

We stock a wide variety of rotation resistant wire ropes from several manufacturers.Some types of wire rope, especially lang lay wire rope, are more susceptible to rotation when under load. Rotation resistant wire rope is designed to resist twisting, spinning, or rotating and can be used in a single line or multi-part system.Special care must be taken when handling, unreeling, and installing rotation resistant wire rope. Improper handling or spooling can introduce twist into the rope which can cause uncontrolled rotation.Call us at 800.362.4601 or click here to get the rotation resistant wire rope you need!

The characteristic of these wire ropes are that the outer layer is twisted in the opposite direction of their inner layers. The sometimes confusing issue is that many 8-, 9- and 10 strand constructions are 2-layer types but their inner strands are NOT twisted in the opposite direction and therefore these rope are NOT spin-resistant; plus, for the untrained eye these ropes look very much alike their spin-resistant variants. These and regular 6-strand ropes will spin violently and unlay themselves when loaded when one rope end is allowed to spin freely. They may also develop a significant drop in breaking strength and an even larger drop in their fatigue life characteristic (Torsion Fatigue).

To achieve any degree of resisting the tendency of a rope to spin and unlay under load all such rope types (other than 4-strand ones) are constructed with 2 or more layers of opposite twisted strands (see picture on right).

2-layer ropes (MULTI, COMPAC 18) have a larger tendency to rotate than 3-layer ones (e.g. Class 34 x 7, COMPAC® 35). Furthermore, 2-layer spin-resistant and rotation resistant ropes will develop only about 55% to 75% of their breaking strength when one end is allowed to rotate freely. This number increases to between 95% to 100% for 3-layer (e.g. COMPAC® 35) non-rotating ropes.

Another important issue is that 2-layer rotation resistant and 2-layer spin-resistant rope types have shown to break up from the inside. The 8 (e.g. 8×25 spin-resistant) or 12 outer strands (19×7, 19×19, COMPAC®18) are not able to evenly distribute the radial forces and because of the inherent internal strand cross overs (which make the rope spin- or rotation resistant) the resultant severe notching stresses cause the rope core to break up premature (unless the core is plastic coated, e.g. Python® Multi). Unexpected and sudden rope failures may be the result. Moreover, 2-layer spin-resistant or rotation resistant ropes satisfy only low to moderate rotational resistance demands.

3-layer rope constructions (e.g. COMPAC® 35) have many more outer strands which can much better distribute the radial pressures onto the reverse lay inner strands. These ropes should be selected for larger mobile- and ALL tower cranes.

This wire rope construction is available in both galvanised and ungalvanised finish with either ordinary or langs lay. The construction family includes 17X7, 18X7 and 19X7. For further flexibility and other performance characteristics we also supply 32X7, 35X7 and 37X7.

Depending upon your requirement for higher breaking load or better wear characteristics, these wire ropes are available in different finishes and lubrications as well as being available with plastic impregnated.

Rotation-resistant rope is defined as stranded rope designed to generate reduced levels of torque and rotation when loaded and comprised of two or more layers of strands laid helically around the center, with the direction of lay of the outers strands being opposite to that of the underlying layer. However, there are different levels of rotation resistance to consider.

Rotation-resistant rope (Category 1): Stranded rope constructed so that it displays little or no tendency to rotate, or, if guided, transmits little or no torque. It has at least 15 outer strands and is comprised of at least three layers of strands laid helically over a center in two operations, with the direction of lay of the outer strands being opposite to that of the underlying layer. This rope is also known as Non-Rotating.

Rotation-resistant rope (Category 2): Stranded rope constructed so that it has significant resistance to rotation. It has at least 10 outer strands and is comprised of two or more layers of strands laid helically over a center in two or three operations, with the direction of lay of the outer strands being opposite to that of the underlying layer. This rope is also known as Low Rotation.

Rotation-resistant rope (Category 3):Stranded rope constructed so that it has limited resistance to rotation. It has no more than 9 outer strands and is comprised of two layers of strands laid helically over a center in two operations, with the direction of lay of the outer strands being opposite to that of the underlying layer. This rope is also known as Spin Resistant.

Northern Strands Mining, Wire Rope, Attachments & Equipment Division excels by providing a wide range of equipment and services, by being the best full service provider of wire ropes, attachments, equipment and service. Truly Mine Hoisting Solutions®.

For customers who require peak rope performance levels in mission critical applications, Casar manufactures and supplies highly-engineered ropes that exceed industry standards while providing record-setting service life.

Our proprietary and innovative German-engineered rope designs deliver the highest levels of performance and safety, superior breaking strength values, the highest bending fatigue resistance, superior crushing resistance, and the best rotational resistance characteristics for high lifts.We have decades of global experience and on-site engineering support in the crane, OEM and underground mining sectors.

CASAR has an extensive range of products available and we can customize to your application.Our wire rope specialists will assist customers in design, selection, installation and operation to improve rope performance and maximize service life.

Main and auxiliary hoist line for mobile and for all types of construction tower cranes which require a high strength rotation resistant rope construction.

The large number of outer strands distribute the pressures introduced by sheaves and drum more evenly onto the core minimizing the danger of unexpected rope failures because of undetected core deterioration.

Aside from this safety issue PYTHON® COMPAC 35 satisfies the high-strength requirements of late model tower and mobile cranes which can NOT be met with neither 19 x 7 nor 19 x 19 style ropes.