Thursday, Jul 25, 2013 at 09:35
Just a little follow up on some very real issues that many people will not be aware of.
First we must understand that there is more to the ADR requirements and the various regulations than a lot of people wish to understand.
Overseas towing practice and the hardware they use, may to some, make our regulations seem inadequate or out dated.....but overseas...especially the US..they have different considerations and a completely different package of regulations.
BTW they seem happy kill a lot more people on their roads than we do in proportion.
ANYway
The standard ADR compliant 50mm tow ball is rated at 3.5 tonnes towed capacity...lets not bother with the fine detail beyond that..except to say that there is not a huge safety margin like there is in lifting gear.
The standard ball has a 7/8" UNF shank....that fits all standard tow bars as factory drilled.
There are variations available, but in Australia, towing a light trailer on a draw bar, rear hitched with a ball is limited to 3.5 tonnes.
If the ball is rated at 3.5 tonnes it will be stamped on the top.
NOW...there are balls available that are only rated at 2.5 tonnes (and less), (not sure about their ADR compliance), but either way they would be adequate for those towing a 750Kg box trailer, but a disaster waiting to happen for anybody doing heavy towing.
Even though my vehicles will not tow 3.5 tonnes, I would not buy or leave fitted a ball rated any less than 3.5 tonnes......its just not worth the $5 saved.
there are also specialty balls available, such as high rise balls, that raise the ball on the towbar around an inch......none of these I have seen are 3.5 tonne rated.
There are 50mm, 3.5 tonne rated balls available with 1 inch shanks, that may address the findamental weakness to a point.
But it requires the tow bar to be drilled out and then a standard ball can not be fitted to that tow bar.
There is a 70mm 4.5 tonne rated tow ball and coupling available in this country BUT neither are ADR approved and thus illegal for use on the road.
The only other ADR approved ball and coupling available is the 9 tonne 3 inch format intended for goosekneck trailers.
Even the use of poly block couplings like the Trigg would be limited to 3.5 tonnes by the standards, but in reality are limited to 3 tonnes.
All heavier draw bar towing goes across to Pintle hook & eye, and lots of industrial users go across to pintle hook at 2 tonnes, mostly because anything that heavy they expect to tow with a truck.
We keep comming back to pushing the limits of the of the format.....AND...realy pushing the limits of safety.
When all states require a truck licence to drive a rigid vehicle over 4.5 tonnes, I remain gob smacked that we allow people to drive combination
well above that limit , towed by a passenger car that is not specifically designed for the purpose and in a form that would be considered fundamentally unstable in heavy transport.
cheers
FollowupID:
794599