Factsheet 13c - September 2005

Full trailers

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Note: The axle set requirements described here apply to heavy trailers. They don't apply to light trailers (with a gross vehicle mass up to 3.5 tonnes).

A full trailer has two axle sets, one of which is connected to the towing vehicle by a drawbar that steers the front axle set.

A heavy full trailer must have a front axle set consisting of either:

• a single axle set, or
• a tandem axle set.

A heavy full trailer must have a rear axle set consisting of either:

• a single axle set, or
• a tandem axle set, or
• a tri-axle set, which is only permitted if the front axle set is a tandem axle set.

The maximum overall length for a full trailer (including drawbar and load) is 11.5 metres.

For a rigid vehicle and full trailer combination (including load, but excluding collapsible mirrors), the maximum overall length is 20.0 metres.

For a full trailer, forward distance means the distance from the rear axis to front of the trailer (excluding the drawbar and front axle set) or its load, whichever is foremost. 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 for a heavy full trailer is 4.0 metres or 50 percent of the wheelbase, whichever is less. The maximum for a light full trailer is 4.0 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 40 percent of the wheelbase of the rigid vehicle. (The wheelbase is measured from the rear axis of the rigid vehicle to the foremost axle of that 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 but including the load). The maximum is 4.0 metres. Full trailers also have a minimum requirement. The minimum inter-vehicle spacing is the greater of 1 metre or half the width of the foremost point of the trailer (including the load but excluding the drawbar).

A drawbar on a full trailer can only have one operating position and cannot be extendable unless it complies with one of the following:

1. it may be retractable only to facilitate the through loading or unloading of livestock or goods, provided that the drawbar has only one set of holes for locking pins and these holes are positioned so the drawbar is fully extended when locked, or
2. if the trailer is used to transport logs, the drawbar may have up to three fixed positions and one sliding position, provided that the drawbar has:
   • one sliding position for long logs, and
   • one or two fixed positions for short logs, and
   • a fixed position for storage of the drawbar when it is out of use while the trailer is being transported on a rigid vehicle or another trailer.

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 20.0 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:

• a twin-steer axle set or a wheelbase of at least 4.25 m and
• at least two motor driven axles in the rear set of the truck.

In addition to these two conditions, the maximum gross mass of the heavy full trailer vehicle combination must not exceed 42 tonnes, unless:

• the towing vehicle has a twin-steer axle set or a tri-axle set, or
• the trailer has two tandem axle sets or the trailer has five axles.