RV FEATURE
THE TOW BALL
The humble tow ball has been the backbone of Australian caravanning for decades . But it too is subject to the Australian Design Rules and Standards . Specifically in relation to ATMs up to 3500kg , the tow ball must be 50mm in diameter and stamped with this dimension on the top of the ball .
It must be a one-piece unit ( i . e ., no welds or joins ), with a shank that ’ s 29mm in diameter . It must also be fitted with a locking / spring washer and appropriate nut , and have the name / trademark of its manufacturer stamped on the flange .
The distance between the ground to the centre of the tow ball ( or tow pin , as the case may be ) must be within the range of 350mm and 460mm .
Even the humble 50mm towball is subject to the Australian Design Rules .
COUPLINGS
Your towing setup is only as strong as its weakest link . Whether we ’ re talking safety chains or suspension and tyres , the lowest-rated piece of equipment will always be your limiting factor . This even extends to the coupling .
The couplings in use in Australia are typically rated to 3500kg , since that ’ s – by and large – the maximum towing capacity of many of our tow vehicles as well as the maximum ATM you ’ ll generally find ( there are certainly exceptions to this , however ).
In any event , the coupling body must be marked with its capacity , along with the name of the coupling ’ s manufacturer and the size of the tow ball for which they are designed .
Offroad couplings are designed to offer greater amounts of articulation than a conventional ball coupling . Whatever the design , they must incorporate a positive locking mechanism along with a separate means of keeping this mechanism locked . Further , this must all be visually verifiable , while both parts of the coupling must be stamped with the manufacturer ’ s name / trademark , the words “ use with model ( identified model )”, and the maximum allowable trailer ATM for which the coupling is rated .
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