Thread: Trailer Safety Chains

Originally Posted by Karl Robbers

Yep, rated "D"shackles or preferably Hammerlocks are the best for attaching safety chains to trailers.
To digress a little, I came in contact with a trailer a couple of weeks back. 4500 Kg ATM, single axle on 17.5" dual wheels, full air brakes with a front mount telescopic tipper. Nice trailer you might say, but it was built and registered with a single pole drawbar - which broke on the second load, the axle was 50mm FORWARD of center, the hitch was attached with mild steel bolts, as was the hoist and it had two pissy little 8mm safety chains.
I really do wonder about the people that build and register trailers some times.
Construct your trailer to be failure free in critical areas, (axle, suspension, drawbar, brakes safety chains and hitch), then add a bit more to be sure.

As the trailer is in excess of 3500kg, it is required to use grade T/grade 80 chain for the safety chains, specifically the standard mandates:

Originally Posted by VSB1

trailers over 3.5 tonnes ATM must have two safety chains made from steel of a minimum 800 MPa breaking stress that conforms to the mechanical properties of Grade T chain as specified in Australian Standard AS 2321-1979 ‘Short Link Chain for Lifting Purposes (non calibrated)’ or Australian Standard AS 2321-2006 ‘Short Link Chain for Lifting Purposes.’ Each chain must be sized such that the minimum breaking load exceeds the ATM.

A ha you might say, because 8mm chain is rated to only 2 tonnes (and therefore less than the 4.5 tonne ATM), except that is a the working load limit and under AS2321, grade T chain has a factor of safety of 4, so the minimum breaking strength is actually 8 tonnes and as such, assuming it was appropriately mounted Grade 80 chain, it would in fact be entirely compliant.

More concerning is the broken drawbar, it would seem unlikely that the drawbar met the requirements of section 14 of ADR 62. My experience with RVCS suggests that actual checking of calculations or physical testing for S14 is very rare. Probably the right thing to do would be to forward your concerns over the failure to RVCS via the relevant minister including the VIN of the the trailer.