RV FEATURE
It is recommended that the towbar overhang be
no more than 30 per cent of the wheelbase.
Because of this, when the tow vehicle is
steered in one direction, the coupling moves in
the opposite direction. This can cause a
dangerous situation if rapid corrective
steering action is required to stop the caravan
from swaying.
The further the coupling is behind the rear
axle of the tow vehicle, the worse the
problem can become. It is suggested that the
towbar overhang be no more than 30 per
cent of the wheelbase.
Coupling and height: The Australian Design
Rules prescribe legal requirements for couplings
(which include balls, couplings, towbars, safety
chains, etc.), including the minimum and
maximum heights of couplings above the
ground, when the vehicles are fully loaded.
In particular, there are specific limits for 50mm
ball couplings because of their limited angles
of articulation. Towbars must have been
strength-tested by their manufacturers, and
have their two ratings – towing capacity and
download – marked on them.
There are towball height
requirements that must be
adhered to.
If the towbar was designed to comply with
ADR 62/01, the centre of the ball, when the
vehicle is fully-laden, must be between
350mm and 420mm above the ground.
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