Trailer safety chain rules and requirements differ all over the world.
In this article, we will cover those that apply to Australia. It is important to note that the Australian design regulations are some of the highest in the world. These are good guidelines to follow if there are no specifics on the topic in your country.
Current vehicle safety standards: Chains
For a new trailer to be licensed, it must first comply with the Vehicle Standard Bulletin – Building Small Trailers (VSB1) requirements. One stipulation of VSB1 is that your trailer has a marked safety chain. In the past, sourcing a chain that met the required standards was challenging – resulting in relaxed rules. These days, however, suitable chains are widely available. You are expected to meet this requirement for all new trailers.
Trailers up to 3.5 tonne ATM
VSB1 states that trailers under 2500 kg ATM must be fitted with at least one chain, while trailers over 2500 kg ATM require two chains.
For trailers up to 3500 kg ATM, chains must comply with Australian Standard AS4177 Caravan and light trailer towing components – Part 4 Safety chains. In addition, for chains welded to the drawbar, welds must cover at least 50% of the length of the link. The adjoining link must be able to move freely within the welded connection.
Manufacturers or importers permanently mark compliant chains with their identification and the digits 4177, followed by a hyphen and the first two digits of the chain load designation. The marking appears at least every four links, with characters that are at least 1.5mm high for chains under 8mm link diameter and at least 2mm high for chains 8mm and larger.
Trailers over 3.5 tonne ATM
Trailers over 3.5 tonne ATM must have chains made from steel with a minimum 800 MPa breaking stress and conforming with mechanical properties of grade T chain as specified in AS2321 Short Link Chain for Lifting Purposes (non-calibrated). The chain must be permanently attached to the trailer. Welding to the drawbar, and shackles, are not permitted. You must use a sufficiently rated safety chain attachment point.
Manufacturers or importers permanently mark compliant short-link chains with their identification marking, which is preceded by the letter T or the numbers 8, 80 or 800. The marking will appear at least every 20 links, ensuring clear identification.
Current vehicle safety standards: Shackles
Shackles (Bow, D or Pin shackles) may be used to attach safety chains to a trailer towbar, but are subject to performance requirements outlined in ADR 62/01 or 02 – Mechanical Connections between Vehicles.
Shackles that are used to attach safety chains to towbar attachment points should:
- Exceed the required safety chain rating (defined by the trailer ATM).
- Be fit-for-purpose.
- Have strength and size compatible with the safety chain.
To meet these requirements, a suitable shackle that also complies with AS 2741-2002 Shackles will have the following permanent markings:
- The manufacturer’s identification (name or trademark),
- The quality grade (M or 4, or S or 6),
- Working Load Limit (WLL) which is the maximum load that may be applied to to the shackle, and
- Identification marking that allows the shackle to be traced to a test certificate.
The following table can be found in original documentation provided by the Australian Government.