Yep Correct Tombie
Cheers
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I would be very surprised if the chain used on trailers and caravans is any where near rated shackle capacity.
The old way of working out chain capacity was D x D x G x .3
i.e.12mm mild steel chain = 12 x 12 x 30 x .3 = 1296kg WLL or approx 4-5 times that for minimum breaking load.
An 11mm rated shackle has a WLL of 1500kg.
Cheers
We're not talking lifting here though... Where the safety margin/factor is high.
Were talking BLL... Think snatch straps... ;)
To drill through all the technicalities - I think it's safe to say that two shackles, each rated at 1.5 T WLL are more than enough and legally sufficient.
Cheers,
Gordon
Egg Zackary
Reading through the March 2015 edition of the RACV's RoyalAuto magazine I came across this interesting article which I thought I'd share. Timely with the Victoria Labor Day long weekend and Easter coming up.
D-RUMOURS DEBUNKED
Rumours of police in several states clamping down on non-load-rated D-shackles being used to tow caravans, boats and other trailers are just that: rumours.
Many members have raised concerns with RACV that they'd be fined for using what they thought was a common towing hitch component.
The Caravan Industry of Australia has told RACV various police and state transport departments have denied any sort of crackdown.
The CIA also confirms there is no specific requirement for D-shackles such as when attaching a trailer to a tow-bar. The Australian Standard on shackles [AS 2741-20021 only covers their use for lifting].
"Our understanding is that there is currently no regulations requiring shackles used on trailer safety chains to comply with the standard," says Stuart Lamont of the CIA. "However,some state authorities provide guidelines or advice for selecting suitable shackles."
Mr Lamont says the CIA does recommend using shackles that meet AS 2741-2002 to secure safety chains up to 3500kg capacity.
The grade should be 'S' or "6",have a 10mm diameter and a working load limit of 1000kg.
Mr Lamont says either bow-shackles or D-shackles are suitable, noting that the bow design provides greater angular uses.
But there is a lot more to safe towing and caravanning than just the shackles. Go to racv.com.au/mycar and follow the Safe Driving link, where you'll find a safe towing article with dozens of tips and guidelines to better caravanning.
I use a simpler method(rated shackle only, couldn't be arsed working all that maths out) If it has a lifting load of 1500kg, double that for the pulling load limit, can't go wrong.
Baz.
The weekend before last, I saw a loaded trailer being towed, restrained only by the chains. I could see it as it came around a corner ahead toward me.
I stopped her and told her the trailer was not coupled to the car. The driver seemed oblivious to the trailer swaying behind her.