Safety Chains, Shackles & Hooks

Why Chains Matter (and Why They’re the Law)

Safety chains are your “just in case” plan. If your trailer coupling ever lets go, the chains are what keep your van connected to the car long enough for you to pull over safely.

That’s why the Australian Design Rules (ADR 62/02) and the Road Vehicle Standards Act (RVSA) make them mandatory. No chains = no compliance, and you could cop a fine, defect notice, or even void your insurance if something goes wrong.

The Two Standards You Need to Know

Here’s where people often get tripped up: not all chains are created equal. In fact, there are two different Australian Standards, and which one you need depends on your trailer’s weight.

AS 4177.4 – For trailers up to 3.5 t ATM

• This is the standard for most caravans and campers.
• Chains must be stamped with “4177-XX” (e.g. 4177-35 for 3.5 t) plus the manufacturer’s ID, repeated every few links.
• You can weld these chains to the drawbar (as long as at least half the link is welded and the first link is free to move) or use hammerlocks or rated connectors.
• 1 chain required up to 2.5 t ATM, and 2 chains between 2.5 t and 3.5 t ATM.

AS 2321 (Grade T chain) – For trailers over 3.5 t ATM

• Heavy-duty chain, originally designed for lifting.
• Must be Grade T steel with a breaking stress of at least 800 MPa.
• No welding allowed — chains must be attached using rated couplings or pin-locks.
• Each chain’s breaking load must meet or exceed the minimum breaking load specified for the trailer’s ATM in AS 2321.

Shackles, Hooks & Hammerlocks – What’s What

Chains alone don’t keep you safe — it’s how you connect them that counts.

Shackles (the traditional option)

• You’ve probably seen bow or D-shackles used everywhere.
• To be legal, they must meet AS 2741. That means they’ll be stamped with:
  • Manufacturer’s ID
  • Working Load Limit (WLL)
  • Grade (M/4 or S/6)
• The WLL must be adequate for your trailer’s aggregate trailer mass (ATM)

Unstamped “hardware store shackles”? Don’t risk it — they’re not rated and won’t pass muster if you’re pulled over.

Hooks (the newer option)

• These are a newer alternative to shackles but you must make sure you are purchasing the compliant options.
• Designed with a spring latching mechanism so the chain can’t bounce out.
• Much quicker to connect and disconnect (no pins to unscrew at camp).

• Only use rated hooks that are permanently marked and supplied with evidence of compliance — such as ADR component approval or conformity with relevant Australian Standards (e.g. AS 3776 for the hook and AS 4177.4 for the chain end).

Hammerlocks

• Handy for connecting chain to the drawbar if welding isn’t possible (for trailers up to 3.5 t ATM).
• Important note: hammerlocks are not a replacement for shackles or hooks at the vehicle end — they’re just a way of attaching chain to the trailer.

How to Attach Chains Like a Pro

Even with the right gear, a dodgy setup can undo all that effort. A few golden rules:

• Cross your chains under the coupling — it creates a cradle that can catch the drawbar if it drops.
• No dragging — chains should have enough slack for tight turns, but not so much that they scrape on the road.
• Check before every trip — look for rust, worn links, or loose pins.
• Attach to proper points only — towbar holes designed for chains, not random bolts or bumper bars.

Quick Reference Table

The Bottom Line

Safety chains, shackles, and now hooks might not be the flashiest part of your setup, but they’re some of the most important. They’re legally required, easy to check, and the difference between a smooth trip and a dangerous situation.

So before you roll out, do a quick chain check. Make sure your gear is stamped, rated, and fitted right. Safe travels!