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Department of Transport and Main Roads

Trailer types and definitions

Trailers over 750kg aggregate trailer mass (ATM) must be inspected by a HVRAS accredited person or at a transport and motoring service centre before being registered in Queensland.

Not all of our transport and motoring service centres conduct trailer inspections. Please check the services provided by each centre to confirm if they can inspect trailers.

Listed below are definitions of the various trailers and the corresponding inspection sheet for these trailer types:

Box (pig) trailer

  • A box (pig) trailer:
    • has 1 axle group or a single axle near the middle of its load carrying surface
    • is connected to the towing vehicle by a drawbar.
  • Complete pig trailer inspection sheet (F3123).

Image of side view of a pig trailer
Caption—an example of a box (pig) trailer

Dog trailer

  • A dog trailer has:
    • 1 axle group or a single axle at the front that is being steered by connection to a towing vehicle by a drawbar
    • 1 axle group or a single axle at the rear.
  • This includes a trailer consisting of a semi-trailer and converter dolly.
  • Complete dog trailer inspection sheet (F3148).

Image showing example of a dog trailer
Caption—an example of a dog trailer

Semi-trailer

Image of side view of a semi-trailer
Caption—an example of a semi-trailer

Lead/middle trailer

Image showing the side view of an example of a lead/middle trailer
Caption—an example of a lead/middle trailer

Converter dolly trailer

Image showing the side view of a converter dolly trailer
Caption—an example of a converter dolly trailer

Low loader dolly

  • A low loader dolly is a device for distributing mass that:
    • is usually coupled between a prime mover and low loader
    • consists of a rigid frame in a gooseneck shape
    • does not directly carry any load
    • is equipped with 1 or more axles, a kingpin and a fifth wheel coupling.
  • Complete heavy haulage/low loader/dolly inspection sheet (F3154).

Image showing the back and side view of a low loader dolly
Caption—an example of a low loader dolly

Low loader trailer

Image showing the front and side view of a low loader trailer
Caption—an example of a low loader trailer

Tag trailer

Image of side view of a tag trailer
Caption—an example of a tag trailer

Caravan

  • A caravan is an enclosed trailer designed for people to live in (includes camper trailers).
  • Complete pig trailer inspection sheet (F3123).
  • A caravan or camper trailer must be equipped with cooking facilities, living or sleeping accommodation.
  • A caravan or camper trailer (including pop-top camper trailer) must have outward-opening or sliding doors. At least 1 door must be located on the left-hand side or at the rear. There is no requirement for doors on trailer-based fold out campers.
  • A caravan or camper trailer designed primarily for human occupation (when stationary) must be fitted with a fire extinguisher. When conducting an inspection on a caravan or camper trailer, it is not a requirement to check the safety or validity of the fire extinguisher.

Image showing the front and side view of a caravan
Caption—an example of a caravan

Mobile equipment trailer or mobile machinery trailer (non-load carrying)

  • A mobile equipment or mobile machinery trailer:
    • has permanently attached equipment that performs specific tasks
    • is not able to carry a load with the exception of any auxiliary equipment for performing the function for which they are designed
    • must be registered with a registration category of STRL (e.g. a compressor trailer)
    • requires a weighbridge certificate/supervised weigh documentation.
  • Complete pig trailer inspection sheet (F3123).

Image showing the front and side view of a mobile equipment trailer
Caption—an example of a mobile equipment trailer

More information

Last updated 14 August 2023

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