G'day Jock,

NSW, Road Transport (Vehicle Registration) Regulation 2007.

Here is the link:
http://www.legislation.nsw.gov.au/maint ... 007+cd+0+N

Scroll down the left side almost to the bottom and click on:
Schedule 2 Vehicle Standards,

then scroll down the right side to:
Part 10 Mechanical connections between vehicles

Division 1 Couplings on all types of vehicles

166 Drawbar couplings

The info I posted earlier was a copy and paste from there.

Cheers,

PeterM.

i've had 2 trailers (not vans) slip the ball, both incidents are now decades ago, i also seen 1 trailer snap the ball, snap the chain and then was stopped from killing anyone (the steep downhill 300metres run in the centre of auckland) by writing off 3 cars. it sat in the back seat of the first which crushed the boot of the 2nd and forced both into the 3rd. i was just a pedestrian in a shop doorway when i heard the 2 'cracks' as first the ball broke then the chain snapped it gave me a healthy respect for an unbraked trailer, it was a petrol driven aircompressor so maybe the entire trailer was @ 1-1&1/2 tons (yes pre metric)
i think the present 2000kg self breaking standard is set too low (imo)

for my 2 instances, the first was youthful ignorance the second adult complacancy. i had 3 double kayaks of the university kayak club on the back of a borrowed trailer that was little more than a 6 by 4 ball weight was about negative something (10? 20?). needless to say after @ 8 hours of driving the coupling worked loose (the days of the nut in a handle) on a down hill run felt it go up & was watching the kayaks noses bounce side to side in the mirror. with luck i managed to accellerate a bit which pulled the 'a' frame down lower than the bumper & i hit the brakes with the chain wrapped around the bumper (gentle not panic).

the second time @ 2 decades later it again was a borrowed 6 by 4, same nut arrangement etc, the trailer was empty & same again except this time there was nothing to 'see' as such but the trailer was wagging & i felt the car wasn't quite right, same idea wait until the trailer pitched froward & lower than the bumper & same breaking.

as for the 'roadway' i never went back to look & never cared, both times i was able to rehitch (the 2nd time stopped at the next hardware store & double nutted it)