Whilst there are many costly alternatives, the 50 mm diameter ball coupling trailer hitches used with caravans is fine for on-road use. One type may be used up to 2.5 tonne, another up to 3.5 tonne. Chapter 6: Trailer hitches explains all.
AL-KO hitch. Pic: AL-KO.
Basic ball hitches work well enough on-road, but, if forced beyond their 15 degrees limit, are likely to break, damage the trailer and/or towing vehicle, or even overturn one or both vehicles. To protect against this, Australian Design Rule 62/00 requires that the height to the centre of the ball must be between 350 and 420 mm when the coupled-up rig is fully laden. (Hitches are available that enable tow ball height to be adjusted between 350 mm and 430 mm.)
The AL-KO version of such hitches has more movement but is best not used if travelling far off-road. It is virtually standard on European ‘vans and is fitted to some Australian and NZ caravans, but few camper trailers.
Chapter 6: Trailer hitches – towbars
The requirements for tow bars are covered by Australian Design Rule 62/01 – Mechanical Connections Between Vehicles. This includes a requirement for them to be tested under specified conditions for a minimum of two million cycles. Some imports do not meet these requirements. Buy only from reliable local suppliers.
Chapter 6: Trailer hitches -safety chains
Trailers under 2.5 tonne are legally required to have only one safely cable or chain but many owners choose to use two. Pic: pwbanchor.
Trailers not exceeding 2.5 tonnes ATM must have at least one safety chain complying with AS 4177.4-1994 or AS 4177.4-2004 caravan and light trailer towing components Part 4: Safety chains up to 3500 kg (7715 lb) capacity’, or a safety cable with a certified load capacity of 3500 kg (7700 lb).
The trailer ends must be welded to the trailer’s chassis. Correctly rated shackles must be used to connect the chains to the tow vehicle. There is no legal obligation for these to be certified – but it makes sense for them to be so.
Trailer hitches -hitches for off-road
As noted above, basic ball couplings are fine for typical dirt roads but cannot be used for any serious off-road going, particularly for steep creek crossings etc., as the couplings’ limited angular movement will inevitably be exceeded – and break or be torn off. There are, however, variants of the above that are suitable for both on and off-road use.
Hyland ball fully off-road hitch. Pic: Hyland.
The Hyland coupling uses a 3.5 tonne 50 mm ball that provides a full 360º degrees movement.
That 3.5 tonne ball can be used with standard ball couplings but not vice versa because that coupling’s movement necessitates an extended stem.
The McHitch. Pic: McHitch
The McHitch Uniglide (right) uses a Toyota universal joint that provides 90º horizontal and vertical movement. Vehicle Components’ Hitchmaster (below) uses a modified version of the 50 mm ball. A smaller tapered section above eases coupling.
Chapter-6-trailer-hitches – Vehicle Components simple yet effective Hitchmaster. Pic: Vehicle Components.
The Australian designed Hitch-ezy (below) also provides 90º up and down and 360º rotation. It is rated at up to 5.0 tonne. A probable 50% of all Australian off-road rigs (in 2018) use the Treg unit.
The Hitch-Ezy does ease coupling. Pic: Hitch-Ezy
The Treg hitches movement is limited by light steel pins to 23 degrees – but the pins seem to be there only to marginally ease coupling. (They tend to sheer off if the trailer is used off-road).
The Treg hitch. Basic but effective. Pic: Treg.
A few Treg users claim it can be difficult to insert and pull out the pin but, as long as it is clean and oiled, coupling and uncoupling is no harder than with conventional tow balls.
Whilst the greater range of movement of off-road hitches is not needed for on-road use, their ease of use, plus lack of rattles etc. are powerful arguments for using any of these units on-road.
Trailer hitches – tow ball mass
Without some tow ball weight, a trailer inevitably ‘fishtails’. Vendors’ recommended nose weights vary widely for camper trailers of almost identical length and weight but 7%-10% of the trailer’s laden weight should be fine. It is however increasingly restricted by tow vehicle’s maker specifications. That tow ball weight is included as part of the tow vehicle’s payload.
A camper trailer’s amount of tow ball mass is less critical than for the typically much longer caravans – but (in the opinion of the Camper Trailer Book) should not be less than 7%.
Weight distributing hitches
Excess weight on the tow vehicle’s rear overhang levers up the front of the tow vehicle, reducing the effective weight on its front tyres. Whilst required only by a trailer towed by a vehicle that is lighter, a weight distributing hitch (WDH) is sometimes used to assist remedy this situation. Its effect is to lever down the tow vehicle’s front wheels. Better by far to have a heavier tow vehicle.
Chapter-6-trailer-hitches – weight distribution hitch. Pic: RV Books.
These hitches must not be used off-road. They impose major forces on the tow vehicle and trailer when they are at an angle: e.g. during tight creek crossings. These forces can be so great that they may bend or tear off the tow bar and/or whatever it is attached to. They also reduce the rig’s cornering power (by up to 25%). They are described here – not recommended.