Are your caravan safety chains the missing link?

ByTim ScottAugust 21, 2020
Are your caravan safety chains the missing link?

The safety chains we use to link van and tow vehicle can be, for some, a confusing area of safety legislation. What’s legal and what isn’t? Don’t let your caravan safety chains be the missing link.

As we covered off in our story about caravan shackles (click here to read) and whether they legally needed to be yellow, the caravan safety chain occupies another slightly grey area. If you need to read more about chains and shackles in a grey area, I suggest you search ‘erotic fiction’.

First and foremost, there are some compulsory elements to this discussion.

When do I need safety chains?

When towing? All the time; they’re compulsory. It’s the weight of the van that is the first determiner.

If your van or trailer has an ATM figure less than 2500kg, you must have one steel safety chain from your caravan drawbar to the tow vehicle. No-one will object to you having two, however, especially if you live in WA, as that state singularly mandates two chains for trailers under 2500kg ATM.

If your caravan or trailer has an ATM of between 2500kg and 3500kg, then you will require two steel chains and these must comply with Australian Standard AS4177-4 and have a rating at least equal to the ATM of your trailer.

Once you crest the 3500kg ATM threshold, your chain’s break load limit should exceed the trailer’s ATM and your chains must be T Grade and meet AS2321. Again, you need two steel chains in this set-up or safety cables that match the capacity of the equivalent steel safety chains on trailers over 3500kg ATM, which is a whopping 800 megapascals (MPa) breaking stress, as a minimum. Of course, this applies to each chain individually.

How do I know I have the right safety chain?

In the way that shackles are stamped with a working load limit (WLL), a diameter and a grading, your chain should carry certain markings. Safety chains must be stamped with the chain’s capacity, the manufacturer’s identification and the digits 4177. See the table below.

Caravan safety chain sizing chart

As we discussed with shackles, the legislation covering chains, is not directly linked for towing, as the document’s name gives away: Australian Standard AS 2321-1979 Short Link Chain for Lifting.

Why do I need safety chains anyway?

If you’ve ever lost your keys, you know how annoying that can be. So you might opt for a key chain. Let’s scale things up a bit and apply that to towing your trailer. There are tremendous forces at play when you’re towing, much more than the drag on your house keys (unless you’re in a very nasty divorce, which can exert more force than a black hole, never mind a tri-axle Kedron). So your safety chains – and your breakaway brakes – are your last line of defence, so to speak, in the event of a trailer separating from your tow vehicle.

Read Next Breakaway brakes: Everything you wanted to know and more

Safety chains are mandatory under the above conditions, and when more than one is used, the chains must be crossed to fasten to the towbar eyes on the tow vehicle (and nowhere else). To spell that out (and remember, not everyone is as experienced as you) from the drawbar on the van, the left chain on the drawbar goes to the right eye on the car, and the opposite with the right chain.

The chains must not be stretched tight when shackled to the hitch point; you should allow enough ‘slack’ to allow for tight turns. Conversely, the chains shouldn’t drag along the ground either!

The point is that should the unthinkable happen and you have a trailer come off the tow hitch, the chains should act as a cradle to stop the drawbar reaching the ground. There’s little point debating all the permutations of possible scenarios. If you’ve really stuffed up the hitching process, and the two do part company as you trundle out of the driveway then this theory may play out perfectly. If the separation happens at 90km/h and with a sway up, then the chaos theory comes into play (that’s my basic reasoning, not scientific rules of the universe).

Of course, the points at which the chains attach to the drawbar and to the eyes on the tow hitch must also be rated to match the capacity of the safety chain. What we mean is, that the hitch hardware must be rated for the towing you’re doing. It’s easy to grab an aftermarket tow hitch of the wrong rating if you don’t know to check. They’re not all created equal either.

How do you fasten the safety chain to the drawbar?

The van manufacturer should no doubt know the legal situation in terms of supplying a van ready to tow. The chain(s) will already be attached, but there are things to check (see the markings above), and if you wish to alter the attachments, you need to be aware of the legal limitations.

Firstly, the chains must be permanently attached to the drawbar, not shackled. Below 3.5 tons ATM the chain can be welded to the drawbar, with a weld forming 50% of the circumference of the link but the first link in the chain must have unfettered movement.

Above the 3500kg ATM then you need to use rated pin lock couplings. No welding is permitted. Careful placement is required to mount the chains as close to the coupling as is practical, and if two points of attachment are needed, then you must place one on either side of the drawbar’s centre line.

A hammerlock for caravan safety chains

What is a hammerlock?

A hammerlock is a device that can be used to lock your safety chain to the mounting point on your drawbar. These can be bought already attached to aluminium mounting plates for fastening to the drawbar. Aluminium plates can be bolted to the steel chassis, not welded. A hammerlock can also be used to reattach a chain (at the drawbar end) you need to lengthen in the way that a shackle can’t.

unrated caravan safety chains

Things you absolutely mustn’t do!

Don’t be tempted to use unrated, hardware-store-bought chain (or shackles).

Given that the rated chain needs to retain its integrity, you must not insert links that are not rated to at least the same break limit as the rest of your chain.

Only one rated shackle is permitted per chain – you cannot extend a chain with shackles, rated or not! But you can use a hammerlock (pictured above.

If your trailer is over 3.5-tons ATM then it’s illegal to use galvanised chain (and shackles).

And if you fancy using your welding skills, you must be aware that you cannot weld the chain below the van’s chassis rails and no welding is allowed in chain-rating situations more than 3.5 tons.

So now we’ve covered off the safety chains as part of your hitch set-up there’s hopefully no confusion and no missing links.