Ratchet Tie Down Strap — a Cargo Lashing, Rated in LC, and Never a Lifting Sling

A ratchet tie down strap: polyester webbing, a plated ratchet tensioner, and a hook at each end. The colour is a webbing choice, not a rating.

1. What a Ratchet Tie Down Strap Is, and What It Is Not

The trade's own definition of the article is worth reading closely, because it names the three parts and the two attachment points in one sentence. A synthetic webbing tie down is "any combination of fittings, webbing and tensioners forming an assembly that attaches to vehicle and cargo anchor or attachment points", used "for securing articles of cargo to a vehicle or restraining articles of cargo from movement on a vehicle". Three parts, two ends, one job: holding a load still.

What it is not is lifting equipment, and the difference is not a matter of opinion or of quality. It is written into the two standards. A synthetic lifting sling made to EN 1492-1 is engineered to a factor of roughly 7:1, and a ratchet lashing made to EN 12195-2 to roughly 2:1. That gap is the whole reason the standard obliges every compliant lashing label to state NOT FOR LIFTING in terms — a strap that is perfectly correct for holding a load down has nowhere near the reserve needed to hold the same load up, and it is also not designed for the shock and the horizontal loading of a lift. A tie down has no lifting capacity, no matter what its LC says, and a lifting sling is not a tie down either: the two are separate products under separate standards and they must not be substituted for one another in either direction.

Because this site sells lifting slings almost exclusively, that warning is the first thing on this page rather than a footnote. The catalogue a buyer arrives from is full of slings; this page is not one of them. If you have come here looking for something to lift with, the flat woven slings and round slings elsewhere on this site are the right products and this is not.

2. The Number You Choose: LC — and Why a Tie Down Does Not Use It

Four values describe a lashing system and they are routinely confused with one another, including in supplier listings that quote whichever number looks largest. They are not interchangeable, and only one of the four is the right number for the way a tie down strap is normally used.

The most useful sentence on the subject comes from a manufacturer's own label guide, and it is unusually direct: "Please note the Lashing Capacity is NOT USED for tie down lashing, in that case, STF should be used." That is not a quibble. LC is the strength of the assembly if something pulls on it; STF is the force it actually presses the load down with. A strap crossing over a load stops the load sliding because it presses it onto the deck and creates friction, and the force doing the pressing is STF. Buying a strap by LC alone therefore specifies the strength of a restraint you were never going to load to that strength.

Two consequences follow, and neither is obvious from a catalogue. First, BF is not a bigger version of the rating. A strap marked LC 2,000 daN must survive 4,000 daN in the standard's test, and the published guidance is careful to say that this "does not make the strap a 4000 daN lashing for operational use" — listings that advertise the breaking force as though it were the capacity are describing a test, not a working limit. Second, STF is not a fixed property of a type of strap. It depends on the tensioner, the handle length and the webbing, which is why it is quoted per product and printed on the fixed-end label rather than assumed.

3. Direct Lashing and Frictional Lashing: Two Jobs, Two Numbers

Everything above becomes practical once the two ways of using a strap are separated, because they use different numbers from the same label. The distinction is set out plainly in the standard's own explanatory material.

Frictional lashing, usually called tie-down lashing, is the strap over the top: it is tensioned to press the load against the deck, and it works by increasing the friction available to resist movement. Its governing number is STF, and its effectiveness depends on the coefficient of friction between the load and the deck, and on the geometry. Direct lashing is the strap arranged so that it acts directly against the movement — from the vehicle's anchor point to the load and back to the vehicle — and its governing number is LC.

This is why the two photographs on this page cannot be specified by one number. A strap over the top of a machine on a flatbed is doing frictional work and its STF is the figure that matters. The same strap run diagonally down to an anchor point on the deck is doing direct work, and its LC is the figure that matters. Most real loads are held by a mixture, and a supplier who quotes only one of the two numbers has not specified the job.

4. Three Standards, Three Rating Systems — and Why LC Must Not Be Compared With WLL

The same physical strap is rated three different ways in the three big markets, and the difference is not a matter of units. It is a different model of what the number means.

Europe rates the strap in LC, in daN, and requires the complete assembly to withstand at least twice that in test — a 2:1 factor. North America rates it in WLL, in kilograms or pounds, against a design factor that is stated as a minimum of 3:1. Australia and New Zealand pair a lashing capacity with a minimum breaking force and put both on a permanent label. The published guidance on choosing between them says the quiet part out loud: these standards "are not interchangeable", and lashing capacity and working load limit "rely on different safety models", so a direct comparison without technical validation may lead to the wrong specification.

One thing the three standards do agree on is the arithmetic within a single system, and it is worth knowing because it shows up on every label. The published size ladder in the trade runs 25 mm webbing at LC 500 daN and BF 1,000 daN, 35 mm at LC 1,000 daN and BF 2,000 daN, and 50 mm at LC 2,500 daN and BF 5,000 daN. In every case the breaking force is exactly twice the lashing capacity: [ARITH] 1,000 ÷ 500 = 2, 2,000 ÷ 1,000 = 2, 5,000 ÷ 2,500 = 2. That is what the 2:1 factor means, and it is why a listing that shows a breaking force of 5,000 with a capacity of 5,000 is showing you a test result being passed off as a rating.

5. The Weaker Number Wins: the Weakest Component Sets the Rating

Every figure on the label belongs to the whole assembly, not to the webbing. The general rule is stated in the US regulation in the clearest possible form, and the European label guidance agrees with it in a single phrase — lashing capacity "is determined by the weakest link in the assembly".

The clause is worth reading twice for two reasons. First, it names the tensioner specifically — the ratchet is not a tool that happens to be attached, it is a rated component and it can be the thing that limits the assembly. Second, it brings in the vehicle's anchor points, which are not part of what you bought. A strap of excellent quality attached to a weak anchor is a weak tiedown, and that is a legal statement rather than an opinion.

And one more rule from the same section of the regulation, aimed at the case where nobody knows what the strap is: synthetic cordage that is not marked so that its composition or working load limit can be identified "shall be considered to have a working load limit equal to that for polypropylene fiber rope". In other words, the law does not assume an unmarked strap is a good one — it assumes the weakest common cordage. Marking is not decoration on this product. It is the difference between the strap's real rating and the lowest guess in the table.

6. The CE Question: a Ratchet Strap Must Not Carry One

This is the question buyers ask most often and it is the one where the correct answer is the opposite of what is expected. A ratchet tie down strap must not be CE marked, and a supplier who puts a CE mark on one has done something the standard forbids rather than something extra for the customer.

The reason is a legal distinction, not a quality one. The CE mark is available only to product categories that fall under a European directive or regulation that requires it. Lifting equipment does — a synthetic lifting sling is governed by the machinery safety framework and must be CE marked. Lashing equipment does not, because EN 12195-2 is not on the European Commission's list of harmonised standards. Cargo restraint sits outside the directives that carry the mark, so applying it is misleading, and the published position is that applying a CE mark to a product that does not fall under an applicable harmonised standard constitutes a legal offence. A major manufacturer states the rule in five words on its own label guide: "A strap can never have a CE label! This is strictly forbidden!"

What replaces the mark is the label, and that is why the European label is so detailed — it carries the identification that a mark would otherwise gesture at, and it does it with numbers. The practical consequence for a buyer or an inspector is simple: if a ratchet strap arrives carrying a CE mark, ask why. Either the mark was applied by mistake, or the product is being presented as something it is not. Neither is a reason to trust it more.

7. The US Rule: Half the Load Weight, and Why a Direct Strap Counts Only Half

North America does not ask for a calculation. It asks for a comparison, and the comparison contains a rule that surprises almost everyone the first time they meet it.

So the target is straightforward — the straps' aggregate working load limit must be at least half the weight of what they are holding — but the way the aggregate is built is not. A tiedown from the vehicle straight to the cargo is counted at half its working load limit. The same tiedown routed over or around the cargo and back to the vehicle is counted in full. Two straps of identical rating are therefore worth different amounts of compliance depending on how they are rigged, and a direct strap has to be twice as strong as an over-the-top strap to contribute the same amount.

[ARITH] Take a 10,000 lb load and 5,000 lb tiedowns. The requirement is an aggregate of at least half the weight, so 5,000 lb. A strap routed over the load counts in full, so it contributes 5,000 lb and meets the requirement on its own — exactly, with no margin, which is why anyone sensible uses two. A strap taken straight from an anchor point to the load counts at half, so it contributes 2,500 lb, and it takes two of them to reach the same 5,000 lb. Same load, same straps, and the routing alone doubles the number required.

Two further pieces of the same section are worth carrying into a specification. The regulation also requires that a securement system for cargo not fully contained by the vehicle structure provides a downward force equivalent to at least 20 percent of the weight of the article — the direct regulatory counterpart of the STF argument in §2. And for particular commodities the aggregate fraction changes: a stack of logs on a frame vehicle needs an aggregate working load limit of at least one-sixth the weight of the stack, while groups of concrete pipe and boulders need at least half. Commodity-specific rules take precedence over the general ones where they add requirements.

Commodity-specific requirements exist for the loads most often carried by readers of a page like this one — dressed lumber and building products, metal coils, paper rolls, concrete pipe, intermodal containers, heavy vehicles and machinery, boulders — and they take precedence over the general rules where they add requirements. They are worth looking up before a first shipment of anything unusual, because several of them change the aggregate fraction rather than merely restating it.

8. What the Label Tells You, and What the Colour Does Not

On this product the label carries the weight that a CE mark carries on a lifting sling, and the European standard is specific about what has to be on it. A manufacturer's own label guide states the consequence of losing it in one sentence: "without this label attached to a strap (or if it is unreadable), you are not allowed to use the strap in any way". The label is not documentation. It is a condition of the strap being usable at all.

The label is also designed to survive partly losing the argument with the load. Its lower section is sewn into the seam of the assembly and repeats the critical identification — lashing capacity, material, manufacturer, traceability code, year of manufacture, standard reference — so that if the exposed part is torn or scuffed, the information is still on the strap. On a tie down that spends its life being thrown over loads and dragged across decks, that is a sensible piece of engineering, and it is why "the label is damaged" and "the label is gone" are two different situations.

Which brings the two photographs on this page back into focus. They show the same article in blue and in orange. The blue assembly is the common polyester one. The orange is a webbing colour choice — useful for visibility on a dark deck, or simply to match a fleet — and neither one is a statement about how much the strap holds. Capacity is read from the printed numbers, always, and a strap whose numbers cannot be read is out of service whatever colour it is.

9. Reading the Geometry: Angle, Edge Loss and One-Side Tensioning

A tie down strap does not hold a load by being strong. It holds it by where it is put, and three published findings explain why two straps of the same rating secure very different loads.

The angle decides which part of the force is doing the work. A strap working at an angle to the deck has two components: the vertical component, which presses the load down and creates friction, and the horizontal component, which acts directly against movement. For a direct lashing the useful restraint is the horizontal component — the capacity multiplied by the cosine of the angle measured from the deck. For a friction lashing the useful part is the vertical component, which goes with the sine of the angle. Both fall away from their best value as the angle moves, and they move in opposite directions, which is why a single strap at one angle cannot be perfect at both jobs.

The belt loses force as it crosses the load. A strap going over the top is deflected twice, once at each edge. On each deflection the tension is reduced by edge friction, and the published analysis puts the practical result plainly: with lashing angles between 80° and 90° and belt-to-cargo friction of 0.20 to 0.25, "only around half the pre-tensioning force applied with the tensioner is actually present on the other side". That is worth sitting with. Tighten a strap as hard as you like at one end and the far side of the load sees roughly half of it, because the load's own edges take the difference.

Which is why tensioning from one side only is more expensive than it looks. When that edge loss is written into the calculation, the usable sum of vertical components becomes 1.5 × FT × sin α rather than 2 × FT × sin α, and the correction has a name: the k factor, defined as 1.5 where tensioning is carried out on one side only and 2 where it is carried out on both. The published consequence is the part that matters commercially: because tensioners are in practice nearly always on one side only, the mathematical securing effect of a tie-down lashing is reduced by 25%, and that loss must be made up by about 33% more belts at the same friction and the same pre-tension. A load that looks as though it needs three straps may need four, and the reason is not the strap.

10. Webbing, Hardware and the Choices That Actually Matter

The article is simple — webbing, a tensioner, two fittings — so the handful of decisions in it decide almost everything. Left unspecified they will all be made for you, usually in favour of the cheapest option, and two of them decide whether the strap does its job at all.

11. Inspection, Use and Retirement

The published inspection list for lashing straps is short and specific, and it is a better guide than any general advice about age. Web straps and their fittings should be checked before use for deterioration or damage that could affect performance, and the damage named is: cuts and tears; abrasion; broken or damaged load-bearing fibres; damaged stitching; heat damage; contamination; and damaged, cracked, deformed or corroded ratchets and end fittings. The instruction that follows is equally direct — where the condition of a lashing means its rated performance can no longer be relied on, it should not be used for load restraint.

Three practical consequences fall out of that. First, there is no replacement interval: the standard does not require an expiration date, so a tie down is not retired because it is old but because it is no longer what it was. Which means the check has to be real, because nothing else is going to stop a tired strap. Second, an unreadable label takes the strap out of service just as surely as a cut does, and this is the failure mode of a tie down rather than of a lifting sling — a strap dragged across a deck abrades its own label, and the sewn-in wrapper section is the standard's answer to exactly that. Third, the list includes the ratchet itself: a cracked, deformed or corroded tensioner is a rated component failing (§5), and it is the part most often ignored because it looks like hardware rather than like the strap.

In use, the rules that come from the regulation are worth keeping in view: a tiedown must not contain knots; anything repaired must be repaired to the applicable standard or the manufacturer's instructions and not improvised; and every tiedown must be attached and secured so that it cannot become loose, unfasten, open or release while the vehicle is in transit. That last one is where hook choice, anchor condition and the geometry in §9 all meet. A load that arrives with a slack strap did not fail because the strap was weak; it failed because the tension it started with was not held.

12. Frequently Asked Questions

Contact

This is a made-to-order lashing strap, and the two answers that decide it are the destination market and the load. Send the country, the load weight, the length between your anchor points and the hook anchor you need, and add whether the straps will go over the top of the load or straight to an anchor point — that last detail alone can change how many you need. Technical questions on this page are answered by the workshop rather than by a call centre, and if the honest answer is that you need a lifting sling rather than a tie down, we will say so.

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