Wire rope construction: 6x19 vs 6x36

Two wire ropes of the same diameter and grade can behave quite differently, because what matters inside is the construction, how the wires are arranged into strands and the strands into the rope. The familiar descriptions 6x19 and 6x36 capture this: the number of strands and the number of wires in each. The construction sets a basic trade between abrasion resistance and flexibility, and choosing the right one for the duty is part of getting long life from a rope, alongside the inspection and care our note on rope inspection covers and the choice of wire versus synthetic our note on wire and synthetic rope sets out.

What the numbers mean

A construction like 6x19 means the rope has six strands, each made up of around nineteen wires, while 6x36 has six strands of around thirty six wires. The first number is the strands, the second the wires per strand, and these are classes rather than exact counts, covering a range of similar constructions. The key difference is the number and size of the wires: 6x19 has fewer, thicker wires in each strand, while 6x36 has more, thinner wires. This seemingly small difference in how the strands are made up changes the rope's behaviour significantly, which is why the construction matters as much as the diameter and grade.

Fewer thick wires: 6x19

A 6x19 class rope, with fewer and thicker wires in each strand, is more resistant to abrasion. The thicker outer wires have more metal to wear away before the rope is weakened, so a 6x19 rope stands up better to being dragged over rough ground, rock or an abrasive surface. The price is that the thicker wires make the rope stiffer and less able to bend repeatedly without fatigue, so it does not last as well where it is bent over small sheaves or wound in many layers. So 6x19 suits abrasive duty with relatively little bending, where its wear resistance is the priority.

More thin wires: 6x36

A 6x36 class rope, with more and thinner wires in each strand, is more flexible and more resistant to bending fatigue. The many thin wires let the rope bend more easily and repeatedly without the wires fatiguing, so it lasts better where it runs over sheaves, bends over a small drum, or is wound in many layers, all of which fatigue a rope by bending it. The price is that the thinner outer wires have less metal to wear, so the rope is less resistant to abrasion than a 6x19. So 6x36 suits duty with a lot of bending, where flexibility and fatigue life matter more than wear resistance.

The abrasion versus fatigue trade

The choice between the two is essentially a trade between abrasion resistance and bending fatigue resistance, set by the wire size. Thicker wires resist wear but fatigue sooner when bent; thinner wires bend repeatedly without fatigue but wear faster. No rope is best at both, so the construction is chosen for whichever the duty stresses more. A rope dragged over abrasive ground with little bending wants the wear resistance of 6x19; a rope cycling over sheaves and drums wants the fatigue resistance of 6x36. Understanding this trade is the heart of choosing the construction, because it is the same trade in every wire rope decision.

Bending over sheaves and drums

How much the rope is bent in use is the biggest factor in the choice. A rope that runs over sheaves, bends over a small drum, or is wound in many layers is bent and flexed repeatedly, and bending fatigue is its main enemy, so the flexible, fatigue resistant 6x36 usually suits. The sheave and drum sizes matter too, because a rope bent over a small radius fatigues faster, the same D/d ratio our note on reeving and sheaves covers. So a winch with reeving, small sheaves or multi-layer spooling generally calls for a 6x36 class rope, while a more abrasive, less bending duty may suit 6x19.

Matching the rope to the duty

The honest way to choose a construction is from the duty: how abrasive the work is against how much the rope is bent. Heavy dragging over rough ground with little bending points to 6x19 for its wear resistance; running over sheaves, small drums and many layers points to 6x36 for its flexibility and fatigue life. Many winch duties, with their drums and reeving, lean toward 6x36, but an abrasive recovery duty may suit 6x19. The construction is chosen together with the diameter, the grade and the duty, so the rope lasts, which we consider as part of specifying a winch and its rope rather than fitting a generic rope. Getting the construction wrong is a common cause of a rope that wears out or fatigues far sooner than expected, so it is worth a moment's thought rather than taking whatever rope is on the shelf.

Construction is one part of rope choice

Construction is important but it is one of several things that decide a rope. The diameter and grade set the strength, the core affects flexibility and crush resistance, the lay and finish matter, and whether wire or synthetic is right comes first, the subject of our note on wire versus synthetic rope. So the construction is chosen alongside these, to suit the abrasion and bending of the duty within the rope size and grade the load needs. Getting all of these right together is what gives a rope that lasts, and the construction is the part that tunes the rope between wear resistance and flexibility for the specific work.

The right rope for your winch with us

We specify the rope, including its construction, to suit the abrasion and bending of the duty, so it lasts. See the range in our winch catalogue, and read how wire and synthetic ropes, rope inspection and reeving bear on the choice. Tell us the duty, how abrasive it is and how much the rope is bent over sheaves and drums, and we will specify a rope whose construction suits the work rather than a generic one.

Frequently asked questions

What do 6x19 and 6x36 mean?

They describe the rope's construction: six strands, each of around nineteen or thirty six wires. The first number is the strands, the second the wires per strand. 6x19 has fewer, thicker wires; 6x36 has more, thinner wires, which changes how the rope resists abrasion and bending.

Which is more abrasion resistant?

6x19. Its fewer, thicker outer wires have more metal to wear away before the rope is weakened, so it stands up better to being dragged over rough ground, rock or an abrasive surface. The trade is that it is stiffer and less resistant to bending fatigue than 6x36.

Which is better over sheaves and drums?

6x36. Its many thin wires let it bend repeatedly without fatiguing, so it lasts better where it runs over sheaves, bends over a small drum or is wound in many layers. The trade is that its thinner outer wires wear faster, so it is less abrasion resistant than 6x19.

How do I choose the construction?

By the duty: how abrasive the work is against how much the rope is bent. Heavy dragging over rough ground with little bending suits 6x19 for wear resistance; running over sheaves, small drums and many layers suits 6x36 for flexibility and fatigue life. The construction is chosen with the diameter, grade and duty.