For trailer safety chains in Australia, start with the Aggregate Trailer Mass (ATM) on the vehicle plate. Under the current national guidance, a rigid-drawbar camper trailer at or below 2,500 kg ATM needs at least one compliant chain or certified safety cable. Above 2,500 kg ATM, it needs two. The chain rating, its connection to the trailer and the device used to connect it to the tow vehicle all need separate checks.
The August 2026 edition of Vehicle Standards Bulletin 1 (VSB1) explains the Australian Design Rule requirements for trailers up to 4.5 tonnes ATM. ADR 62/02 is the national vehicle standard behind the drawbar, safety-chain and attachment-point requirements. After a trailer enters service, registration, roadworthiness and modification rules are administered by the relevant state or territory.
That division matters. A chain can carry the correct Australian Standard marking yet still be connected to the wrong towbar point, joined with an unsuitable shackle or left with excessive slack. This guide shows what each official document establishes and what an owner can verify before towing.
Trailer safety chains in Australia: the threshold table
VSB1 section 9.2 applies safety-chain requirements according to ATM, not the trailer’s measured weight on one trip.
| Trailer ATM | Minimum national requirement in VSB1 | Chain or cable specification |
|---|---|---|
| Up to and including 2,500 kg | At least one safety chain | AS 4177.4-2004 chain, or a safety cable with the same certified load capacity |
| Over 2,500 kg to 3,500 kg | Two safety chains | Each chain must comply with AS 4177.4-2004, or use a safety cable with the same certified load rating |
| Over 3,500 kg to 4,500 kg | Two safety chains | Grade T chain meeting the mechanical properties in AS 2321-2001; each chain must have a minimum breaking load above ATM |
The threshold is over 2,500 kg. A trailer with an ATM of exactly 2,500 kg falls in the first row; a trailer rated at 2,501 kg falls in the two-chain row.
VSB1 says safety chains or cables must be fitted to all trailers without an emergency brake system and to all trailers with rigid drawbars, whether or not they have emergency brakes. A typical camper trailer is a rigid-drawbar trailer, so the presence of a breakaway system does not remove the safety-chain requirement. The two systems perform different tasks, as our breakaway brake system guide explains.
ATM is a manufacturer rating that includes the mass imposed through both the trailer tyres and the coupling at maximum load. It is not the same as GTM and is not whatever the trailer happens to weigh today. If the terms are unclear, check the current ATM, GTM and tare definitions before selecting a chain or connector.
Read the AS 4177 marking on the chain
For a trailer at or below 3,500 kg ATM, VSB1 says an AS 4177.4-2004 compliant chain carries three elements in its marking:
- the manufacturer or importer identification;
4177; and- a hyphen followed by two digits showing the designation.
The marking must repeat at least every fourth link. In the bulletin’s example, 4177-35 identifies a 3,500 kg designation. The published selection table is:
| Chain designation | Trailer ATM covered |
|---|---|
| 1,000 kg | 0–1,000 kg |
| 1,600 kg | Up to 1,600 kg |
| 2,500 kg | Up to 2,500 kg |
| 3,500 kg | Up to 3,500 kg |
Use the ATM recorded for the trailer, even when it normally travels well below that limit. For example, the VSB1 table puts a 1,700 kg ATM camper in the 2,500 kg chain designation. A current weighbridge ticket showing 1,500 kg does not lower the trailer’s ATM or change the rating category.
Do not infer capacity from link diameter, colour or appearance alone. VSB1 tells manufacturers they need evidence that a chain supplier meets the relevant standard; adding a marking to an otherwise undocumented chain is not evidence by itself. An owner checking an existing trailer can record the complete marking and ask the trailer manufacturer or chain supplier for the specification if it is missing, illegible or does not align with ATM.
Trailers above 3,500 kg ATM use a different chain specification. VSB1 identifies Grade T chain, with T, 8, 80 or 800 markings, and warns that T-rated chains should not be welded. The bulletin’s low-ATM scope ends at 4,500 kg, so heavier trailers require the applicable ADR and heavy-vehicle requirements rather than an extrapolation from this guide.
The trailer attachment point carries its own requirement
The rating stamped into a chain does not certify the bracket, weld, bolt or drawbar structure holding it to the trailer. ADR 62/02 and VSB1 treat those attachment points separately.
The national documents require a safety-chain attachment point on the drawbar to be:
- attached to a substantial structural member of the trailer;
- as near as practical to the coupling; and
- placed one on each side of the drawbar centreline where two chains are required.
Each attachment point must withstand a longitudinal tension of 9.81 × ATM in kilograms and a vertical tension of 0.5 × 9.81 × ATM in kilograms. The forces are applied separately for at least 10 seconds, without a break, crack, component separation or residual deformation that interferes with the assembly.
Those are compliance test conditions, not a do-it-yourself owner test. VSB1 says the testing facilities used for its accepted method must be approved under section 111 of the Road Vehicle Standards Rules. An owner can inspect for visible cracking, distortion, severe corrosion, loose fasteners and unauthorised changes, but a visual check does not prove that the point passed its required load test.
If an attachment has been moved, replaced or added, ask for the engineering or approval record supporting the modified configuration. The vehicle plate and RAV comparison can establish the recorded identity and mass ratings, but neither record proves the present condition of a weld or bracket.
A shackle connects the chain; it does not rate the whole system
The chain is normally fixed to the trailer at one end and connected to a designated towbar attachment point at the other. Australian Government Administrator’s Circular 0-1-3 gives owners and operators a uniform way to choose a connection device for trailers up to 3,500 kg ATM.
The circular describes a bow shackle, D-shackle or a pin-shackle arrangement at the towbar attachment point. It says the device should exceed the required safety-chain rating and be compatible with the chain in strength and size. For shackles complying with AS 2741, its table gives these minimum Working Load Limits (WLL):
| Trailer ATM | Minimum shackle WLL | Grade M D-shackle body | Grade S D-shackle body | Grade S bow-shackle body |
|---|---|---|---|---|
| 0–1,000 kg | 250 kg | 6 mm | 6 mm | 5 mm |
| 1,001–1,600 kg | 400 kg | 10 mm | 6 mm | 6 mm |
| 1,601–2,500 kg | 625 kg | 13 mm | 8 mm | 8 mm |
| 2,501–3,500 kg | 875 kg | 16 mm | 10 mm | 10 mm |
The dimensions are body diameter, not pin diameter. The lower WLL number does not mean the shackle is weaker than the trailer ATM: the circular explains that AS 2741 shackles are rated for lifting, while the loading differs in a trailer connection. Use the table as published rather than comparing WLL directly with ATM.
An AS 2741 shackle should show the manufacturer identification, quality or grade, WLL and a traceable identification marking. The circular also describes a compatible shackle from a reputable brand where its brand or part marking can be traced to the manufacturer’s strength information.
The circular is guidance, not legislation. It expressly says there is no legal obligation to follow that document and that anyone choosing another device is responsible for demonstrating to the state or territory authority that it is appropriate. The practical check is therefore the current local rule, the towbar manufacturer’s instructions and traceable product evidence together.
Never attach a chain to an unapproved hole, bumper part or other convenient point merely because a shackle fits. The circular discusses connection to the towbar attachment points, which themselves are subject to ADR performance requirements.
Chain length and crossing depend on in-service rules
National design requirements establish the chain, number and drawbar attachment. State and territory authorities administer the trailer once it is in service, and their connection instructions must also be followed.
NSW Government guidance says safety chains should be as short as practicable and connected so the front of the drawbar does not hit the ground if the coupling disconnects. It also says two chains must be crossed. The same page tells travellers to check the relevant road authority when entering another state because rules can differ.
Crossing two chains is therefore a documented NSW instruction, not a claim that every jurisdiction uses identical wording. Before travelling, check the current rule for the states and territories on the route, along with the trailer and towbar manuals. Chain length must still allow the normal articulation of the combination without binding, pulling tight or dragging on the road.
Keep the safety chains separate from the breakaway cable or switch lanyard. The breakaway system is designed to apply the trailer brakes after separation; the chains are the mechanical safety connection. Follow the manufacturer’s routing instructions for both so one does not interfere with the other.
A pre-tow safety-chain check
Complete these checks with the trailer stationary and secured:
- Read ATM from the trailer’s vehicle plate and compare it with the public RAV entry.
- Confirm the required number of chains from the ATM threshold and trailer type.
- Record the complete chain marking, including manufacturer or importer identification and the AS 4177 designation where applicable.
- Confirm that each chain’s designation covers the trailer ATM.
- Inspect each link for distortion, deep corrosion, cracks, unauthorised welding and heavy wear.
- Inspect the trailer attachment points and nearby drawbar for cracks, distortion, corrosion, loose fasteners or repairs.
- Use only the towbar’s designated safety-chain attachment points.
- Check every connecting device for traceable markings, compatible size and the rating specified by the applicable guidance and manufacturer.
- Connect the chains with enough movement for turns and articulation, without unnecessary slack or road contact.
- Apply the current state or territory instruction on chain crossing and connection.
- Route and test the breakaway system separately where one is fitted.
- Stop and obtain advice from the manufacturer, an appropriately qualified repairer or the road authority if a marking or modification cannot be verified.
This inspection cannot establish hidden damage, material strength or compliance test results. It can identify missing evidence and visible faults before departure. Chain condition is also only one part of the towing check; coupling security, brakes, tyres, lights and all applicable mass limits remain separate requirements. Our trailer brake threshold guide covers the GTM-based braking rules.
What the documents do not establish
The official record does not support several common shortcuts:
- A second chain does not compensate for an underrated chain or attachment point.
- A chain that looks thick enough is not proven to meet AS 4177.
- A rated shackle does not certify the towbar point, trailer bracket or chain.
- A breakaway system does not remove chains from a rigid-drawbar camper trailer.
- A lower measured trip weight does not change the ATM used to select the chain rating.
- A visual owner inspection does not reproduce an ADR strength test.
If a used camper trailer has no traceable chain markings or shows a changed drawbar attachment, preserve photographs and the seller’s documents before arranging an assessment. Do not create a rating by stamping the chain or rely on an online product description that cannot be tied to the fitted component.
Disclosure and verification
Camper News AU is independently edited by Gauthier T., who works with brands in the Australian camper trailer industry, including Breath Trailer. Breath Trailer supplied no data, selected no conclusions and received no favourable treatment. No manufacturer or model is promoted, scored or compared in this article.
We checked the August 2026 VSB1 Revision 6 PDF, the current ADR 62/02 compilation, Australian Government Administrator’s Circular 0-1-3 and the NSW Government towing guidance on 18 September 2026. The national documents distinguish first-supply standards from state and territory in-service administration, so this article does not turn one jurisdiction’s connection instruction into a national rule. Future amendments or local requirements may change the position; any material change will be handled through our corrections process.