Can I build my own trailer? – YES
Can I buy plans to build my own trailer? – YES
The following information relates to building Low ATM (≤4,500kg) Trailers.
What you need to know about building a home-made trailer
To successfully build your own DIY trailer (also known as a ‘Concessional Trailer’) in Australia, there are a few things you need to consider.
The first and most important is ensuring your trailer complies with applicable legislation, allowing you to register your new trailer for use on public roads.
Australian legislation, VSB1 (Vehicle Standards Bulletin) outlines the requirements your trailer must adhere to in order to meet trailer registration requirements. The VSB1 specifies ADRs (Australian Design Rules) and AS (Australian Standards) that your light trailer (4.5 tonnes or less) needs to meet.
We’ve outlined what you need to know about this information to ensure you’re aware of your responsibilities as the builder of your own trailer.
Trailer Components
Certain trailer components need to meet applicable ADRs. Often the easiest way to prove that a component you have used is compliant is by purchasing components that have already been tested by the manufacturer. These components are assigned a CTA (Component Type Approval) number. This number signifies that the component has been tested and meets the applicable ADR. CTAs may be used as evidence of compliance with the National Road Vehicle Standards.
To check a manufacturer’s CTA number, you can cross reference it on the CTA website.
Below is a list of components we recommend you source with a CTA number.
Couplings
Trailers with an ATM ≤3,500kg must be fitted with a 50mm ball coupling based on one of the following ATM weight classes:
- ≤750kg
- ≤2,000kg
- ≤3,500kg
Couplings must have a positive locking system, along with an additional feature that automatically keeps the lock secured. You must also be able to visually confirm that the coupling is properly locked.
Couplings must be prominently AND permanently marked with:
- Manufacturer, trademark or factory mark — check that the supplier has a CTA number to ensure the coupler will meet ADR requirements.
- ’50’ to indicate the 50mm tow ball diameter.
- The rating (based on the above applicable ATM classes).
Other styles of couplings are available. For example, a 70mm ball coupling is commonly used for trailers with an ATM 3500-4500kg.
Note: Coupling height should be between 350mm and 460mm from the ground when loaded.
Lamps (lights/reflectors)
There are many allowable lights/reflectors and arrangements, however we strongly recommend consulting the VSB1 to ensure you meet the minimum requirements. In our experience, lights/reflectors are commonly overlooked by DIYers, resulting in cases of non-compliance.
Below is a summary of the lighting requirements based on trailer size. For more information, including information on light and reflector positions, visit VSB1 pages 20-46.
Trailer size
Requirements
All trailers
Rear: Position lamps, brake lamps, indicator lamps, reflectors, number plate light.
Front/Side: Reflectors
>4m long and wider than 1.6m OR wider than 1.8m
Front: Position lamps
Wider than 2m
Front/Rear: Clearance lamps
Side: Marker lamps
Longer than 6m
Side: Marker lamps
Safety Chains
A safety chain must be fitted to all trailers.
Trailers with an ATM <2500kg only require one safety chain.
Trailers with an ATM >2500kg but not exceeding 3500kg, require two safety chains.
For either of the above ATM categories, the chains must comply with AS 4177.4-2004 Caravan and light trailer towing components – Safety chains up to 3,500kg capacity, or be a safety cable with the same certified load capacity.
Trailers with an ATM >3500kg must have two safety chains. These chains must be made from steel with minimum 800 MPa breaking stress that conforms to the Australian Standard AS 2321-2001 Short-link chain for lifting purposes.
Here is a general guide for selecting the correct safety chain.
Trailer ATM
Chain Rating
Chain Marking
Link diameter
# Chains Req.
Safety Chain Markings
Chains that comply with AS 4177.4-2004 should be marked in the following way:
- Manufacturer or importer identification.
- 4177
- A hyphen and two digits.
- Markings should be repeated at least every fourth link.
For example, 4177-16 indicates a 1600kg chain rating as shown in the iamge.
Safety Chain Attachment Points Must Be:
- Attached to a substantial structural member of the trailer.
- Located as near as practical to the trailer coupling.
Where two safety chains are used, they must be mounted one each side of the centreline of the trailer.
We recommend purchasing an ‘off the shelf chain attachment point’ which has been tested and supplied with a CTA number. This should be fixed to the trailer as per the manufacturer’s directions.
Additional information
Overall Trailer Dimensions
- Max width: 2.5m
- Max height: 4.3m (4.6m livestock)
- Min running clearance: 100mm
- Ground clearance (tandem/tri): midpoint = axle spacing (m) x 33.33
- Pig trailers: 12.2m max length, 8.5m drawbar
- Dog trailers: 5m drawbar, rear overhang ≤ 3.7m or 60% wheelbase
Drawbars
The drawbar needs to meet the requirements set out in ADR 62/02 (Mechanical Connections Between Vehicles).
To prove that your drawbar meets the requirements you can either purchase a drawbar with a CTA number or have your drawbar physically tested or FEA tested. Component type approval can be an expensive process (especially for a one-off build).
Fabplans trailer plans are certified, meeting ADR 62/02 – saving you the time, money and the hassle involved in certification.
Brakes
Trailer brake requirements are determined by Gross Trailer Mass (GTM).
A handbrake is not required on a trailer, however, it is a useful feature and something worth considering.
Tyres
All wheels and tyres, including any retreaded tyres, must comply with the relevant ADRs. This includes ADR 23 (Passenger Car Tyres), ADR 95 (Installation of Tyres), ADR 96 (Commercial Vehicle Tyres) and ADR 42 (General Safety Requirements).
Mandatory Tyre Markings
- Manufacturer – name/brand of tyre.
- Tyre size – E.g. 265/75 R16 where; 265 is the tyre width (mm), 75 is aspect ratio, R is tyre construction (radial), 16 is rim diameter (inch).
- Load rating – indicated by load index E.g. 108 – corresponds to a rating of 1000kg.
- Speed rating – indicated by speed index E.g. L – corresponds to a speed rating of 120km/h.
- Date of manufacture.
Vehicle Plate or Placard (VIN Plate)
Every trailer must have a vehicle plate:
- Made of a durable metal material.
- Permanently attached to the trailer (welded, riveted, or otherwise permanent).
- Letters/numerals must be BLOCK ≥ 2.5mm high – embossed, engraved, etched, indented, or printed permanently.
- Placed somewhere clearly visible and not on a replaceable part (this is generally the drawbar).
Information Required On Vehicle plate
- Manufacturer’s name or Vehicle Make – for home-built trailers submitted via ROVER, “Concessional Trailers” may be used.
- Trailer model.
- Vehicle Identification Number (VIN) – For new trailers this is acquired through the ROVER application.
- Date of manufacture.
- ATM (Aggregate Trailer Mass) in kg.
- GTM (Gross Trailer Mass) in kg.
- Tare Mass in kg.
Additional Inclusions
- Tyre size
- Tyre load rating
- Speed rating
- Cold inflation pressure
IMPORTANT: The details on the VIN plate must EXACTLY match the details submitted in your ROVER application. Incorrect Tare, GTM, ATM etc., constitutes an offence.
VSB1 also recommends stamping a secondary VIN into a substantial structural part (e.g. trailer drawbar).
Electrical
Electrical wiring must be:
- Supported at intervals no more than 600mm apart.
- Insulated at joints.
- Should not chafe or contact moving parts.
- When passing through metal, use rubber grommets.
- Earthed (ground wire) between trailer and tow vehicle. Trailer cannot be earthed through the coupler.
- Must use either a 7 or 12 pin plug that complies with AS4177.5-2004.
Registration Plate
All trailers must be fitted with registration plates. Plates should be located at the rear, orientated with the long edge horizontal, and should be no more than 1300mm from the ground.
