Shackles for Safety Chain Connections (3.5t ATM)

There is a lot of misinformation about safe towing, including what components are needed to connect the safety chain to your caravan and trailer.

Couplemate™ discusses some of the critical facts you should know about safety chains on trailers and debunks some of the myths discussed around the campfire about shackles and safety chain connections. Some of the most common questions customers ask about safety chains involve their rating and the ability to extend them.

This blog forms part of the Couplemate™ Technical Unit on Towing.

Types of Shackles: Permanent

Permanent shackles and connections may be used to extend chain length.

Dee or bow shackles must be compatible with a chain rated for their use. Therefore, the safety chain must have a stamp with a rating. Police or safety inspectors may ask you to prove the dee-shackle is compatible with the safety chain.

So, how do you do that? Please refer to the Australian regulations, which are linked here.

Furthermore, all shackles, hammerlocks, and safety chain ratings should be verified with a Certificate of Conformity (CoC), which can be accessed through the product’s manufacturer if required (CI-119C, Page 2, para 3).

There are two types of shackles: permanent & non-permanent.

Drawbar Holders (i.e. Attachment Points)

We have had a few comments questioning the legality of rated safety shackles being a requirement under the law. Please see more information below:

Can they be used to extend chain length? YES.

ADR 62/02

14.3.1.3. For trailers over 3.5 tonnes ‘ATM’, the chain must be a steel of a minimum 800 MPa breaking stress, conforming to the mechanical properties of Grade T chain. Specified in Australian Standard AS 2321 – 2001 Short Link Chain for Lifting Purposes and must be of a size such that the minimum breaking load exceeds the ‘ATM’.

The drawbar holders must be welded in the correct position. The chain should not come into contact with the road surface while the trailer is not in use or doesn’t have a link.

A welded chain holder is a legal requirement. The plate holding the safety chain holder should be secured to the chassis rail. Previously, the chain may have been attached via a bolt passing through the chassis rail and safety chain co-jointly.

The safety chain can be legally attached to an aluminium trailer chassis via Couplemate™ safety chain holders.

Hammerlocks (i.e. Butterfly Clips)

We have had a few comments questioning the legality of rated safety shackles being a requirement under the law. Please see more information below:

Can they be used to extend chain length? YES.

ADR 62/02

14.3.1.3. For trailers over 3.5 tonnes ‘ATM’, the chain must be a steel of a minimum 800 MPa breaking stress, conforming to the mechanical properties of Grade T chain. Specified in Australian Standard AS 2321 – 2001 Short Link Chain for Lifting Purposes and must be of a size such that the minimum breaking load exceeds the ‘ATM’.

Types of Shackles: Non-Permanent

Non-permanent shackles and connections cannot be used to extend chain length.

Like hammerlocks, non-permanent trailer chain shackles must be marked or stamped with the appropriate information (and be fit for purpose).

D-Shackles & Bow Shackles

The last six words in this clause require rated or stamped dee shackles. You must be able to prove your chain complies with your rated ATM.

Dee shackles and bow shackles are very similar in application. The primary difference lies in their shape design, as illustrated in the images below. It is acceptable to use rated bow shackles in place of a dee shackle.

Chain Hooks (i.e. Mawby Hooks)

The last six words in this clause require rated or stamped dee shackles.

Couplemate™ only stock the AustLift brand of safety chain hooks.

Truth vs. Myth

You need a ‘coloured pin,’ i.e. yellow or red, rated shackle to comply with various state rules.
Myth: Trailer safety chains must be rated at or above the trailer’s ATM. The break load limit of the shackle must be 1.5 tonnes greater than the ATM. Shackle colours are not necessary.

Shackles must have a mark or stamp; deep shackles must be rated appropriately to the chain’s capacity.
Both the chain and shackle have a stamp indicating their rating.

Rated Dee Shackles can be used on trailers weighing up to 4.5 tons.
Myth: Dee shackles or bow shackles attach the safety chain to the chain holders. Alternatively, half of the chain link can be welded to the trailer chassis, up to 3.5t, provided the mounting position does not cause the chain to come into contact with the ground when disconnected or detached. Trailers over 3.5t must use chain holders with Grade 80 safety chains attached.

Key Points for chain attachment.

• Up to 2.5t trailers and caravans require a single safety chain with a rating that can connect to a chassis rail by an approved and rated hammerlock or similar device.
• 2.5t up to 3.5t trailers and caravans must have two safety chains that can be welded or fixed to a chassis rail by an approved and rated hammerlock or similar device.
• 3.5t to 7.2t safety chains must be Grade 80 and attached to the trailer and towbar using a high tensile 4140 pin.

Important notes:

• One safety chain attachment point is required on a trailer up to 2.5t – VSB1.
• Two chains are required on a trailer over 2.5t – VSB1.
• Requires crossing the chain under the tow bar receiver when linking to the tow bar.
• The size of each chain must be such that the minimum breaking load exceeds the ATM.
• The working load is stamped on the chain or shackle. – VSB1.
• The breaking load is the working load multiplied by 6. – WA CI119C.
• Drawbar safety chain attachments should not contact the road surface when the trailer is disconnected from the vehicle. – VSB1.
• Chains must be permanently connected to the trailer, and we do not permit the use of shackles for trailers exceeding 3.5t. QLD AIS 12(a).
• Rated shackles approved as tow bar attachments over 3.5t, provided breaking load 1.5 times ATM – WA CI119C.
• The safety chain attachment points of the trailer and tow vehicle must be as close as possible to the coupling. QLD AIS 12(a).
• Herc-Alloy 800 is the required chain for all trailers over 3.5t. (usually a coloured chain) QLD AIS 12(a).

Safety Chain attachment points – QLD AIS 12(a)

Chain attachment points must be capable of withstanding the following minimum forces without incurring either residual deformation that would interfere with or degrade the function of the assembly or any breaks, cracks or separation of components:

• Longitudinal tension and compression (N) 1.5 x 9.81 x ATM (in kg)
• Vertical Tension and compression (N) 0.5 x 9.81 x ATM (in kg)

Concerning this, the tow bar attachment point on trailers under 3.5t holds a rating of 1/2 of the rating of the tow bar. As a result of an upgrade over 3.5t, you must also upgrade the attachment point to accommodate the full ATM.