Full trailerA full trailer has two axle sets, one of which is connected to the towing vehicle by a drawbar that steers the front axle set.
Note: the axle set requirements described here apply to heavy trailers. They don’t apply to light trailers (that is, trailers with a gross vehicle mass (GVM) of up to 3.5 tonnes).
A heavy full trailer must have a front axle set consisting of either:
A heavy full trailer must have a rear axle set consisting of either:
The maximum overall length for a full trailer (including drawbar and load) is 11.5 metres.
For a towing vehicle and full trailer combination (excluding load) the maximum overall length is 20 metres.
For a towing vehicle and full trailer combination (including load if load overhanging the rear of the trailer does not exceed 2.3 metres in width, or 1.15 metres from the longitudinal centre-line of the vehicle) the maximum overall length is 22 metres.
For a full trailer, forward distance means the distance from the rear axis to the front of the trailer (excluding the drawbar and front axle set with its associated carriage) or its load, whichever is foremost. The maximum distance is 8.5 metres.
Rear overhang means the distance from the rear axis to the rear of the vehicle or its load, whichever is greater. The maximum for a heavy full trailer is 4 metres or 50 percent of the wheelbase, whichever is less. The maximum overhang for a light trailer is 4 metres.
The wheelbase of a full trailer is the distance from the rear axis of the trailer to the centre of the front axle set of the trailer.
For full trailers, front overhang means the distance from the centre of the turntable that connects the front axle set to the chassis of the trailer, to the foremost point of the vehicle (including its load, but excluding the drawbar). The maximum is 2.04 metres radius arc ahead of the turntable centre.
For a rigid vehicle towing a heavy full trailer, the tow coupling position must not be further behind the rear axis of the towing vehicle than a distance equal to 45 percent of the wheelbase of the rigid vehicle.
For full trailers, inter-vehicle spacing means the distance between the towing vehicle (excluding the tow coupling shroud) and the trailer (excluding the drawbar and front dolly assembly but including the load). The maximum distance is 4 metres. Full trailers also have a minimum inter-vehicle spacing of either 1 metre or half the width of the foremost point of the trailer (including the load but excluding the drawbar), whichever is greater.
This is the same as for heavy rigid vehicles.
A drawbar on a full trailer can only have one operating position and cannot be extendable, unless it complies with one of the following:
Note: when fully extended, the drawbar dimension must be such that the length of the trailer does not exceed 11.5 metres and the total length of the combination vehicle does not exceed 20 metres.
A drawbeam must not be sliding or adjustable.
The maximum gross mass of a rigid vehicle and one full trailer in combination is 39 tonnes, unless the towing vehicle has:
In addition to these two conditions, the maximum gross mass of the heavy full trailer vehicle must not exceed 42 tonnes, unless:
Semi-trailer
* A semitrailer with a quad axle set and two steering axles is limited to 18 metres (and must have been first registered before 1 December 2017).
A semi-trailer has one axle set, attached to the towing vehicle at one of these two coupling positions:
Note: trailers attached to the towing vehicle behind the above positions are considered simple trailers (including Stinger Steer Vehicles).
A heavy semi-trailer must have a rear axle set consisting of either:
The gross mass of a semi-trailer (including its load) is the mass transferred to the ground through the axle(s) of that trailer. Any transferred weight from a following attached trailer is to be included in the calculation of gross mass of the first trailer.
The maximum gross mass of a rigid vehicle and one semi-trailer is 39 tonnes, unless it has at least two motor-driven axles in the rear set of the rigid vehicle.
The maximum overall length for a rigid vehicle and semi-trailer combination (including load, but excluding collapsible mirrors) is 19 metres, or 18 metres if it has a quad axle set with two steering axles.
For a semi-trailer, forward distance means the distance from the rear axis to the centre of the kingpin. The maximum is 9.2 metres.
The maximum rear overhang for a heavy semi-trailer is 4.3 metres or 50 percent of the forward distance, whichever is less. The maximum for a light semi-trailer is 4 metres.
For semi-trailers, front overhang means the distance from the centre of the kingpin to the foremost point of the vehicle (including its load). The maximum is 2.04 metres radius arc ahead of the kingpin.
A heavy rigid vehicle towing two trailers must be:
A-train
B-train
Note: a light rigid vehicle (for example, a car or ute with a GVM of up to 3.5 tonnes) may only tow one trailer. Light tractors, however, are allowed to tow two trailers at a speed not greater than 50km/h providing that the tractor’s manufacturer’s ratings are not exceeded.
For an A-train, the rigid vehicle must have at least two motor-driven axles in its rear axle set. A-trains and B-trains must not have retractable or rear-steering axles.
For a B-train, the rearmost semi-trailer must not be coupled further rearward than the rearmost axle of the lead semi-trailer.
The coupling point distance for an A-train is the distance between the rear axis of the semi-trailer and the centre of the tow coupling connecting the full trailer to the semi-trailer. The maximum allowed is 30 percent of the forward distance of the semi-trailer.
The maximum overall length for a heavy rigid vehicle towing two trailers (including load, but excluding collapsible mirrors) is 20 metres.
Simple trailerA simple trailer is a trailer that has one axle set, and is not a semi-trailer.
A simple trailer is attached to the towing vehicle at a position well behind the position specified for a semi-trailer. Stinger Steer Transporters are simple trailer combination vehicles.
The gross mass of a simple trailer (including its load) is the mass transferred to the ground through the axle(s) of that trailer. Any transferred weight from the following trailer is to be included in the calculation of the gross mass of the first trailer. The gross mass of a combined rigid vehicle must not exceed 36 tonnes unless it meets certain requirements on a permit then can be up to 40 tonnes.
A heavy simple trailer must have an axle set consisting of:
The maximum overall length for a simple trailer (including drawbar and load) is 12.5 metres. The maximum overall length for a rigid vehicle and simple trailer combination (including load, but excluding collapsible mirrors) is 22 metres.
For a simple trailer, forward distance means the distance from the rear axis to the centre of the point of attachment of the towing vehicle. The maximum is 8.5 metres.
Rear overhang means the distance from the rear axis to the rear of the vehicle or its load, whichever is greater. The maximum rear overhang for a heavy simple trailer is 4 metres or 50 percent of the forward distance, whichever is less.
For a light simple trailer, the maximum rear overhang is 4 metres.
For simple trailers, front overhang means the distance from the centre of the tow coupling to the foremost point of the vehicle (including its load). The maximum is 2.04 metres radius arc ahead of the tow coupling.
For a rigid vehicle towing a heavy simple trailer, the tow coupling position must be at least 700 millimetres behind the rear axis of the rigid vehicle and not more than a distance equal to 50 percent of the wheelbase of that vehicle. The wheelbase is measured from the rear axis of the rigid vehicle to the foremost axle of that vehicle.
Note: for Stinger Steer Transporters, ‘tow coupling’ includes an articulated fifth wheel attachment with kingpin, or a ball attachment.
There is no minimum inter-vehicle spacing for simple trailers. The trailer (or its load) may overhang the towing vehicle.
ImportantDrivers of vehicles that tow simple trailers (those with one axle set that aren’t semi-trailers) also need to be aware that the simple trailer can impose a large weight on the rear of the towing vehicle that can (by lever action through the chassis of the vehicle) reduce the effective mass bearing on the front axle(s) of the towing vehicle. Simple trailers therefore need to be loaded carefully so that their load is distributed centrally over the axle(s) of the trailer. This will allow the towing vehicle to maintain front wheel traction. Note: loading on a simple trailer is critical, as there needs to be a small downward force on the tow coupling to make sure a simple trailer remains stable while it’s being towed. |
Pole trailersA pole trailer is a trailer attached to a towing vehicle by a telescoping or sliding pole, which is designed to support a common long load spanning between the trailer and the towing vehicle.
The maximum overall length for a pole trailer is 11.5 metres (drawbar fully extended, but excluding the load). The maximum overall length for a rigid vehicle and pole trailer combination (including load, but excluding collapsible mirrors) is 20 metres.
Front overhang for pole trailers is the distance from the centre of the turntable on the towing vehicle to the foremost point of the load. The maximum is 2.04 metres radius arc ahead of the turntable centre on the towing vehicle (that is, the load on the trailer may hang forward of the turntable centre on the towing vehicle by this distance).
The maximum gross mass of a rigid vehicle and the pole trailer combination is 39 tonnes, unless the towing vehicle has at least two motor-driven axles in its rear axle set.
A heavy pole trailer with one axle set must have an axle set consisting of:
For a pole trailer with one axle set, forward distance means the distance (excluding load) from the rear axis of the trailer to the centre of the point of attachment to the towing vehicle. The maximum distance is 8.5 metres, measured with the drawbar at full extension.
Rear overhang is the distance from the rear axis to the rear of the vehicle or its load, whichever is greater. The maximum rear overhang for a heavy pole trailer with one axle set is either 4 metres or 50 percent of the forward distance of that trailer, whichever is lesser. The maximum rear overhang for a light pole trailer with one axle set is 4 metres.
A heavy pole trailer with two axle sets must have a front axle set consisting of either:
A heavy pole trailer with two axle sets must have a rear axle set consisting of:
For a pole trailer with two axle sets, forward distance means the distance (excluding load) from the front axis of the trailer to the centre of the point of attachment to the towing vehicle. The maximum is 8.5 metres, measured with the drawbar at full extension.
For a pole trailer with two axle sets, rear overhang is the distance from the rear axis to the rear of the vehicle or its load, whichever is greater. The maximum for a heavy pole trailer with two axle sets is either 4 metres or 50 percent of the wheelbase of the trailer (where the wheelbase is measured from the rear axis to the centre point of the front axle set), whichever is lesser. The maximum for a light pole trailer with two axle sets is 4 metres.
