Wire rope grades explained: 1770, 1960 and 2160 N/mm2

Open any wire rope specification table and you will find three columns of minimum breaking force sitting under headings that read 1770, 1960 and 2160. Most catalogues, including plenty of good ones, never explain what those numbers are.

They are wire tensile grades, measured in newtons per square millimetre, and they are the last of the four decisions that define a rope after strand count and construction, compaction and core type. Grade is the simplest of the four to understand and the easiest to get wrong, because the obvious move, taking the biggest number available, is often not the right one.

What grade actually means

Wire rope grade is the tensile strength of the individual wires the rope is made from. A 1960 grade rope is built from wire with a nominal tensile strength of 1960 newtons per square millimetre of wire cross-section.

It says nothing about the rope as an assembly. It describes the raw material. The rope's own breaking force comes from that wire strength multiplied by how much steel is in the cross-section and how efficiently the construction uses it, which is why grade and construction are separate questions.

Where the numbers come from

Higher tensile wire is produced by drawing carbon steel rod through a series of progressively smaller dies. Each pass reduces the diameter and work-hardens the steel, raising tensile strength. Carbon content and heat treatment before drawing set the starting point, and the number of drawing passes takes it the rest of the way.

So 2160 grade wire is not a different alloy. It is the same family of steel taken further through the same process, which is exactly why it comes with the trade-off covered further down.

What grade changes, and what it does not

Grade changes minimum breaking force. That is the whole list.

It does not change rope diameter, unit weight, construction, core type, flexibility, or how the rope fits the machine. A 20 mm 8xK26 at 1960 grade is dimensionally identical to the same rope at 1770. Same weight per metre, same fit on the drum, same behaviour over the sheave. It simply breaks at a higher load.

This matters practically. If a rope is at its limit and the diameter cannot change because the reeving will not take it, grade is one of the few levers that works without touching the machine.

How much each grade adds

The published figures are consistent across the range. Here is 8xK26 as a representative example.

Across every construction in the range, the step from 1770 to 1960 averages about 10.7 percent and is remarkably stable, varying only slightly by diameter. The step from 1770 to 2160 averages about 20 percent but is far more variable, running anywhere from 14 to 26 percent depending on construction and size.

The practical lesson is to read the figure at your actual diameter and construction rather than applying a percentage. The 1960 rule of thumb holds well. The 2160 one does not.

What a higher grade costs you

Not money, primarily. The premium for a higher grade is usually modest. The cost is ductility.

The strength and ductility trade

Work-hardening steel raises its tensile strength and reduces its ability to deform before fracture. A higher grade wire is stronger and less forgiving. It tolerates less bending, less shock, and less abuse before it cracks rather than yields.

In a rope that shows up as reduced bending fatigue life and lower tolerance of shock loading. On a machine with generous sheave ratios and smooth operation, the effect is small. On tight sheaves, snatch loading, or a duty cycle with sudden load transfer, it can outweigh the strength gain entirely.

Where this bites hardest

Rotation-resistant constructions deserve particular care. They are already less tolerant of shock loading than conventional rope, as covered in the rotation-resistant guide. Combining the highest grade with a snatch-loading duty compounds two weaknesses rather than solving anything.

Three ways to get more breaking force

When a rope is marginal, grade is one of three levers, and it is often not the best one.

Diameter is the biggest lever and usually unavailable, because sheaves, drums and rope guides are fixed. Compaction is the next largest and brings crush resistance with it. Grade is the smallest step but the cheapest and quickest, with no change to fit or weight.

If you need substantially more capacity at a fixed diameter, compaction and grade stack. A compacted construction at 1960 against a line contact rope at 1770 is a very large step up, and it is the combination most upratings end at.

A worked example

A 24 mm 8xK26 hoist rope at 1770 grade, published minimum breaking force 462 kN. The application requires a safety factor of five, so the permissible working load is 92.4 kN, or roughly 9.4 tonnes.

The crane is being uprated to lift 10 tonnes, which needs about 98 kN of working load and therefore 490 kN of minimum breaking force at the same safety factor. The current rope is 28 kN short. Diameter cannot change, because the sheaves and rope guide are sized for 24 mm.

Moving to 1960 grade takes the same rope to 511 kN, giving a working load of 102.2 kN. That clears the requirement with a little in hand, without touching the machine, without changing the rope weight, and without altering how it spools.

Going straight to 2160 would give 544 kN and a working load of 108.8 kN. More margin, but it buys headroom the application does not need while trading away fatigue tolerance. If this crane runs a high duty cycle over modest sheaves, 1960 is the better specification even though 2160 is available.

Had the shortfall been larger, say a jump to 15 tonnes, no grade change would cover it. That is a construction or diameter problem, and grade is the wrong lever.

Grade in the standards

Grade designations look universal but the standards express them slightly differently, which matters when a specification crosses regions.

EN 12385

The European standard states rope grade in newtons per square millimetre directly, which is where 1770, 1960 and 2160 come from. It is the most common convention in crane and lifting applications outside North America, and it is the one the TJ Steel Rope tables follow.

ASTM A1023

The American standard historically works in imperial units and uses different grade descriptions, including improved plow steel and extra improved plow steel. Those correspond approximately rather than exactly to the metric grades, and breaking forces are published in pounds-force or short tons rather than kilonewtons.

If you are matching a European specification to an American one, convert the breaking force figures rather than assuming the grade names map across. They are different systems that arrive at similar places.

GB/T

The Chinese national standard uses the same newtons per square millimetre convention as EN 12385, so 1770, 1960 and 2160 read identically. TJ Steel Rope produces to EN 12385, ASTM A1023 and GB/T, and which one appears on the certificate is worth confirming at order stage if your inspection regime requires a particular standard.

Grade across the range

All three grades are available across every construction in the catalogue, which is not true of every manufacturer and is worth knowing when you are comparing quotations.

Because grade does not change geometry, this means any construction in the range can be specified at any of the three without affecting fit. The decision is purely about the breaking force you need against the ductility you are prepared to give up.

Grade, breaking force and working load

This distinction gets confused often enough to be worth stating plainly.

Minimum breaking force is the load at which the rope is guaranteed not to fail during a destructive test. It is a minimum, not a typical value, and it is not a load the rope should ever see in service.

Working load limit is minimum breaking force divided by a safety factor. That factor is set by the standard or regulation governing your equipment and application, not by the rope manufacturer and not by the supplier. Different applications carry very different factors, and a rope that is legal on one machine may not be on another.

So moving up a grade raises minimum breaking force by about 10 or 20 percent, and therefore raises the permissible working load by the same proportion under the same safety factor. It does not change the safety factor, and it does not license you to work the rope harder than the standard allows.

Grade and certification

Grade is a certification, not a preference. It should appear on the mill test certificate supplied with the rope, alongside the actual measured breaking force from the test sample.

Confirm the grade at quotation rather than assuming it, and ask for the certificate with the order. TJ Steel Rope produces to EN 12385, ASTM A1023 and GB/T standards, and mill test certificates are available on request. The full certification list is on the certifications page.

If a supplier quotes a breaking force without stating the grade it corresponds to, the number is not usable. The same rope has three different published figures.

A sanity check for any spec table

Grade behaves predictably, which gives you a quick way to test whether a specification table is sound.

Minimum breaking force must rise as grade rises, at every diameter, without exception. Higher tensile wire cannot produce a lower breaking force in the same rope. If the 2160 column shows a figure at or below the 1960 column at the same diameter, the table has an error in it.

The same applies down the column. Breaking force must rise with diameter within a grade. A larger rope of the same construction and grade cannot be weaker.

These checks take a few seconds and catch transcription errors, mixed-up columns, and data copied between constructions. It is worth running them on any table you are about to specify from, including ours.

Note for TJ: this check found seven rows on the 6xK36 Parallel Lay product where the 2160 figure is below the 1960 figure, at 38, 40, 42, 44, 46, 48 and 50 mm. Flagged separately. Recommend correcting before this article publishes, since it invites readers to run exactly this test.

How to choose a grade

Work in this order and grade becomes the last and easiest decision rather than the first and riskiest.

Fix the diameter from the machine, since the drum, sheaves and rope guide decide it and you rarely get a choice.

Choose the construction from the duty, using strand count for flexibility and fatigue, compaction for crushing and drum wear, core for internal wear.

Calculate the minimum breaking force you need, being the working load multiplied by the safety factor the governing standard requires.

Then take the lowest grade that meets it. Not the highest available. The lowest that satisfies the requirement, because everything above that is ductility you have paid for in reduced fatigue tolerance and gained nothing for.

Move up a grade only when the lower one does not meet the figure and diameter cannot change.

Does grade apply to every wire in the rope?

Not necessarily, and this is a detail worth understanding when comparing quotations closely.

A rope described as 1960 grade is built predominantly from 1960 grade wire, but the outer and inner wires within a strand are not always drawn to identical tensile strength. Manufacturers sometimes vary it deliberately, using slightly lower tensile outer wires for better abrasion tolerance and higher tensile inner wires to recover the strength. The published minimum breaking force accounts for whatever combination is used, which is why the rope figure rather than the wire figure is what you specify against.

The practical consequence is that two ropes quoted at the same grade and diameter from different manufacturers can have different published breaking forces. Compare the kilonewton figure, not the grade label, and read it from the certificate rather than the catalogue when the margin is tight.

It also explains why the 1770 to 2160 gain varies so much across constructions while the 1770 to 1960 gain stays near 10.7 percent. At the top grade there is more variation in how manufacturers distribute tensile strength through the strand.

Galvanised and grade

Galvanising is a separate specification from grade, and the two are occasionally conflated on enquiries.

Zinc coating protects against corrosion. It does not add strength, and depending on the process it can slightly reduce the published breaking force compared with bright wire of the same grade, because the coating occupies part of the wire diameter and the drawing process differs.

If you need both corrosion protection and a specific breaking force, state the grade and the finish separately and check the published figure for the galvanised version rather than assuming it matches the bright equivalent.

Common mistakes

Treating higher grade as a free upgrade

It trades against ductility. On tight sheaves or shock-loaded duty that trade can cost more fatigue life than the strength gain is worth.

Applying the 20 percent rule to 2160

The 1770 to 1960 step is a reliable 10.7 percent. The 1770 to 2160 step ranges from 14 to 26 percent depending on construction and diameter. Read the actual figure.

Quoting a breaking force without the grade

Every rope has three published figures. A breaking force with no grade attached is not a specification.

Confusing breaking force with working load

Minimum breaking force is a destructive test minimum. Working load limit is that figure divided by the safety factor your standard requires.

Reaching for grade before construction

If the rope is failing on crushing or fatigue rather than tension, a higher grade will not help and may make it worse. Diagnose the failure mode first.

Grade and rope life

Buyers often assume a higher grade rope lasts longer. It depends entirely on what is ending the rope's life.

If the rope is being discarded because it is close to its load limit and broken wires are appearing under tension, a higher grade genuinely extends life by increasing the margin between working load and breaking force.

If it is being discarded on bending fatigue, meaning broken wires clustered where the rope passes over sheaves, a higher grade will shorten life rather than extend it. Less ductile wire cracks sooner under repeated flexing. The answer there is a construction with more wires per strand, or a larger sheave, not more tensile strength.

And if it is being discarded on crushing or abrasion, grade is irrelevant in both directions. Those are geometry and surface problems that compaction and construction address.

So the honest position is that grade extends life in one specific failure mode and shortens it in another. Diagnosing which one you have is worth more than any amount of specification guesswork.

Frequently asked questions

What does 1960 mean on a wire rope?

1960 is the tensile grade of the wire the rope is made from, in newtons per square millimetre. It describes the raw wire strength, not the rope's breaking force. A 1960 grade rope has roughly 10.7 percent higher minimum breaking force than the same rope at 1770 grade, at the same diameter and construction.

What is the difference between 1770 and 1960 wire rope?

Only the tensile strength of the wire, and therefore the minimum breaking force. Diameter, unit weight, construction, core and fit on the machine are identical. Across the range, 1960 grade adds about 10.7 percent to minimum breaking force compared with 1770.

Is 2160 grade wire rope always better?

No. It has the highest breaking force, but raising tensile strength trades against ductility, so a 2160 grade rope tolerates bending fatigue and shock loading less well than a lower grade. On tight sheave ratios or snatch-loaded duty a lower grade can last longer.

How much stronger is 2160 than 1770?

About 20 percent on average, but it varies considerably, from roughly 14 to 26 percent depending on construction and diameter. Unlike the 1770 to 1960 step, which is consistently around 10.7 percent, the 2160 figure should be read from the table at your actual size rather than estimated.

Does a higher grade rope fit the same machine?

Yes. Grade changes minimum breaking force only. Rope diameter, unit weight and construction are unchanged, so a higher grade rope spools and reeves identically. This is why grade is a useful lever when the diameter is fixed by the machine.

How do I convert minimum breaking force to working load limit?

Divide the published minimum breaking force by the safety factor required for your application. That factor comes from the standard or regulation governing your equipment, not from the rope manufacturer. Minimum breaking force is a destructive test value and never a working load.

Should I raise the grade or change construction?

Diagnose the failure first. If the rope is failing in tension or you simply need margin at a fixed diameter, grade works. If it is crushing on a multi-layer drum, or fatiguing over small sheaves, a compacted construction or a different strand count addresses the actual cause where a higher grade will not.

Is wire rope grade shown on the certificate?

It should be. Grade is a certification rather than a preference, and it belongs on the mill test certificate along with the measured breaking force from the test sample. Confirm the grade at quotation and request the certificate with the order.

Can I mix grades on the same machine?

Not on the same reeving. Each rope on a machine should be specified and documented individually, and the working load calculation depends on knowing which grade is fitted. Mixing grades without recording which is where makes the inspection and load calculation unreliable.

Why do some tables show three breaking force columns?

Because the same rope is manufactured at three tensile grades, and each produces a different minimum breaking force at the same diameter. The three columns are the same physical rope specified with wire of different tensile strength. Every figure in the table must rise as you move from the 1770 column to the 2160 column.

Get a quote

Send the diameter, construction, core and grade with the length required, and ask for the mill test certificate with the order. If you are unsure which grade the duty needs, give the working load and the safety factor your standard applies, and the required minimum breaking force falls out of that. TJ Steel Rope manufactures 6 mm to 80 mm to specification. See OEM and custom orders, or request a quote.