Safety chains and breakaway cables: the bit everyone forgets to check

Pulled into the servo at Nagambie a while back, filling up before a run north, and the bloke on the next pump was under his van with a torch, swearing at something under the drawbar. Turned out his safety chains had been crossed under the coupling since the day he bought the van, three years and God knows how many thousand kays ago. Never crossed. Never once. He'd just never looked.

That's the thing with safety chains and the breakaway cable. They're the gear you fit once, ignore for years, and hope you never actually need. Most of us could recite our tow-ball weight to the kilo but couldn't tell you the rated capacity of the chains bolted to our drawbar. I'll admit I was much the same until a chat with a weighbridge operator in Dubbo set me straight a few years back, and I've been fussy about it ever since.

What safety chains are actually for

The whole point of a safety chain is simple: if the coupling lets go, whether that's from wear, a badly done-up hitch, or the ball coming loose, the chains hold the van attached to the tow vehicle long enough for you to get stopped. They're not decorative. They're not there to stop the van swaying. They're the last line of defence between "close call" and "van in the ditch."

In Australia, safety chains for trailers over a certain mass need to meet requirements under the Australian Design Rules, and the relevant state road authority (VicRoads, Transport for NSW and so on all reference the same national standard) sets out how many chains you need and their rated capacity relative to the trailer's aggregate mass. For most vans over roughly 2.5 tonnes ATM you're required to run two chains, each individually rated to handle the full towing capacity, not the two combined. That trips people up. It's not "one chain rated for the job and a spare"—both chains need to be up to it on their own.

The crossover nobody explains properly

Cross the chains under the drawbar, not just left-to-right in a straight line. If the coupling fails, a crossed chain forms a cradle that catches the drawbar and keeps it off the road, rather than letting it drop and dig in like a plough. I've seen photos of what happens when a drawbar hits bitumen at 100 km/h with an uncrossed chain barely holding on. Not something you want to explain to Denise from the side of the Newell Highway.

Chain length matters too. Enough slack that you can get around tight corners without the chains going tight and yanking on the chassis, but not so much slack that the drawbar can hit the ground if the coupling separates. I run mine with about a hand's width of sag when the rig's coupled up straight. If your chains are so long they're dragging near the road on a sharp turn, shorten them. Most hitch manufacturers sell shortening clips for exactly this, cheap as chips at any caravan accessory place.

Breakaway cables: the part everyone forgets

Different job entirely. The breakaway cable is wired into your electric brake system, and if the van separates from the tow vehicle completely, it yanks a pin that applies the van's brakes hard, independent of the tow vehicle. Without it, a fully detached van just rolls off wherever momentum and camber take it, unbraked, which is about as bad as towing gets.

The cable needs to be short enough that it activates before the safety chains run out of slack, not after. If your breakaway cable is looped with metres of extra length "just in case," you've defeated the purpose. It should pull tight and trigger before the chains take the full load. I check mine every hitch-up now, mostly because I didn't for years and got lucky.

The other bit people skip: the breakaway battery. It's a small sealed battery inside the breakaway switch box on the drawbar, and it needs enough charge to hold the van's brakes on for a reasonable period, not just fire once and go flat in thirty seconds. Most only need a top-up charge every so often, but if you've never checked it, do it before your next trip. A flat breakaway battery is one of those things that looks fine sitting in the shed and fails exactly when you don't want it to.

Checking your chains are actually rated

Every safety chain sold for this job should have a stamped rating on the link or the plate near the attachment point, expressed in kilograms. Compare that figure to your van's ATM, not your tow-ball weight, not the ball rating, the aggregate trailer mass. If you've upgraded to a heavier van, or added a second battery and water tank and crept your payload up over the years (worth a read of our piece on payload creep and why your van weighs more than the day you bought it), it's worth checking the chains are still rated for what you're actually towing now, not what you were towing when you bought it.

Rust is the other killer. Chains live under the drawbar getting sprayed with road grime and salt for years, and a corroded link can be well under its rated strength even though it still looks solid enough to hold. Have a proper look at each link on both chains at least yearly, and if you've been on anything like the Oodnadatta Track or the Birdsville Track with dust and corrugations working everything loose, check them again straight after.

Attachment points and the D-shackles

The chains need to be bolted to the chassis itself, not to the coupling or the jockey wheel bracket, so if the coupling fails the chassis is still what's being held. Use rated bow shackles, not the cheap unrated ones from the hardware store bargain bin, and do them up properly with a spanner, not just finger-tight. I've seen blokes use whatever shackle was in the toolbox because the original went missing somewhere between Coober Pedy and home. Fine in a pinch for one trip, but get the right one back on before you head off again.

This whole area ties in with your general hitch-up routine. If you haven't got a proper checklist you run through every single time, before you've even started rolling out of the driveway, it's worth reading our piece on the hitch-up checklist that stops driveway disasters. Chains and breakaway cable are two lines on that list, and they take about ninety seconds to check properly. I reckon that's cheap insurance against a very bad afternoon.

What I actually do before every trip

Six years into the Big Lap and my routine hasn't changed much. Chains crossed under the drawbar, shackles done up with a spanner not fingers, breakaway cable clipped with just enough slack to allow full lock turns but no more, and a look at the breakaway battery charge every few months rather than waiting for it to fail. None of it takes long. It's the checking-nothing that catches people out, like the fella at Nagambie who'd towed three years with his chains straight instead of crossed and never known any different.

My honest opinion, and I know some will disagree: I think too many new tourers get sold on brake controllers, weight distribution hitches and fancy anti-sway gear (all worth having, to be fair) while the cheap steel chains bolted under the drawbar get treated as an afterthought. They're the cheapest, simplest part of your whole towing setup and the one that matters most if everything else has already gone wrong.

A few common questions

Worth running through a couple of things I get asked at camp kitchens up and down the country, because the same questions come up again and again.

Do you need two chains or is one enough? For most vans over the threshold mass set out in the ADRs, yes, two chains, each independently rated for the job. Check your van's compliance plate and manual, and if in doubt ask your local transport authority or a caravan dealer who does inspections.

Can you use a strap instead of a chain? No. Straps stretch, degrade with UV, and don't have the same rated failure mode as chain and shackle. Not compliant, not safe.

How do you know your breakaway battery still has charge? Most switch boxes have a small test button or LED. Check the manual for your specific brake controller and breakaway unit, and if you're not sure, get it tested next time you're at a caravan service centre, which ties back nicely to our article on what a proper annual service actually covers.

Anyway, that's enough on chains for one yarn. Next time you're hitching up, get down there with the torch before you pull out of the driveway, not after something's gone wrong on the Hume.

— Trev Sanders, Grey Nomad Correspondent, Conquer Australia