Heavy machinery load restraint: What you need to know

There’s an old sailing adage that says: “If you can’t tie a knot, tie a lot” and while that might work on a boat, it’s certainly not the case in road transport.

As a driver or business owner, it’s imperative that you understand how to tie down heavy equipment safely and securely, to prevent both an accident and a fine.

Transporting heavy machinery poses unique challenges due to the size, weight, and complexity of the load.

The immense forces and vibrations experienced during transit can cause the equipment to shift, slide, or even tip over, leading to disastrous consequences.

Consequently, proper load restraint is crucial to prevent such incidents and protect the equipment and other road users.

However, achieving effective load restraint requires a deep understanding of the dynamics involved and the application of appropriate techniques.

Effective load restraint also reduces the strain on the equipment’s structure, minimising the risk of structural failures caused by excessive stress or vibrations.

Moreover, by adequately restraining the load, we can optimise the weight distribution, preventing imbalances that could affect the stability of the vehicle carrying the machinery.

Several factors influence the effectiveness of load restraint techniques. Understanding these factors is crucial for unlocking the secrets of heavy machinery load restraint. Some of the key elements include:

Equipment characteristics: The transported machinery’s size, weight, and shape greatly influence the load restraint requirements. Different types of equipment may demand specific techniques or additional restraints to ensure their stability during transit.

Transport vehicle and trailer: The design and condition of the transport vehicle and trailer directly impact load restraint. Properly designed trailers with appropriate tie-down points and load-bearing capacities are essential for secure transportation.

Road conditions: The quality of roads and driving conditions can affect load restraint. Rough terrain, sharp turns, or sudden braking can subject the load to additional forces, necessitating more substantial restraints and appropriate precautions.

Regulatory standards: Compliance with local and national regulations is crucial for load restraint. These standards define the minimum requirements for securing loads and may include specifications regarding load distribution, the number of restraints needed, and the type of equipment required.

A transport chain is a highly durable lashing type with low-stretch characteristics commonly called high-tensile chains. These are widely used for this purpose, providing strength and reliability. However, determining the load rating of these chains requires careful consideration of various factors.

The chain used for load restraint should comply with Australian Standard AS/ NZS 4344 Motor vehicles – Cargo restraint systems – Transport chain and components. The standard aims to prevent cargo movement during transportation, reducing the risk of accidents, injuries, and damage to both the cargo and the vehicle.

There are five key aspects covered by AS/NZS 4344 that include:

Cargo restraint systems: The standard provides guides on various types of cargo restraint systems, including chains, straps, webbing, and other components used to secure cargo in a motor vehicle. These systems are designed to withstand the forces and stresses generated during transportation.

Load limits and working load limits: AS/NZS 4344 specifies the load limits and working load limits for different types of cargo restraint systems. These limits are essential to ensure the cargo is adequately secured and the restraints can handle the expected loads during transit.

Testing and certification: The standard may outline testing procedures and requirements that cargo restraint systems and their components must undergo to receive certification. This ensures that the systems meet specific safety standards and perform as intended.

Proper installation: AS/NZS 4344 may include guidelines for correctly installing cargo restraint systems, such as adequate attachment points, tensioning techniques, and securing methods. Proper installation is crucial to the effectiveness of the restraints.

Maintenance and inspection: The standard might also cover recommendations for regular maintenance and inspection of cargo restraint systems to ensure they remain in good working condition and can safely secure the cargo.

It’s important to note that standards can be subject to updates and revisions over time. Therefore, we recommend checking the latest version of the Australian Standard AS/NZS 4344 from official sources for the most up-to-date version.

To determine the load rating of a high-tensile chain, you must first familiarise yourself with the chain’s specifications. The manufacturer typically provides these specifications and includes essential details such as material composition, diameter, and grade.

High-tensile chains are available in different grades, such as Grade 80 and Grade 100. The grade denotes the chain’s strength and load-carrying capacity.

Higher-grade chains offer greater strength and are better suited to heavy-duty applications. The chain’s grade is usually marked on the links or packaging.

Ensure that the chain you’re using meets the required grade for your load restraint needs. The most common chain is an 8mm high-tensile transport chain with a typical lashing capacity of 3800 to 4000kg. Other sizes of transport chain are 6, 7.3, 10, 13 and 16mm.

The Working Load Limit (WLL) is the maximum load a chain can safely carry under normal operating conditions.

To determine the WLL, you must consider factors such as the chain’s grade, diameter, and the specific standards or regulations governing load restraint. This information usually is available on the chain manufacturer’s Safety Data Sheet (SDS).

It is essential to thoroughly inspect each chain to ensure there are no knots or twists in any sections of the chain while under tension. Also, check if any chain sections are attached to anchor points using knots. And it goes without saying that no chain sections are joined with wire or bolts. Importantly, look for links that do not match the lashing capacity of the chain assembly.

Furthermore, if a chain has been used to tow heavy vehicles, thoroughly inspect the chain before using it for load restraint and discard it if it is stretched or damaged.

When assessing the serviceability of chains and attachments in relation to AS/NZS 4344, if any of the following conditions exist, replace the chain or attachment, such as the hook.
• Any link weakened by wear, damage or corrosion that reduces its diameter by more than 10 per cent
• Any bent, twisted, stretched or collapsed link
• Any link repaired by welding or any unsuitable repair link or joined by a bolt or wire
• Any attachment (turnbuckle, load binder, grab hook, etc.) weakened or prevented from functioning by wear, damage or corrosion
• A knot in any portion of the chain

The two types of shortening hooks used on chains are grab hooks, either plain or winged, and claw hooks.

Again, inspect each hook for damage and ensure it is the correct size for the chain used. The Load Restraint Guide recommends using winged grab hooks wherever possible because they prevent the chain link from bending and will not weaken the chain.

Conversely, plain grab hooks can weaken the chain by bending the links they contact, thereby reducing the lashing capacity of the chain by 25 per cent.

On the other hand, claw hooks distribute the force evenly into the chain. However, some claw hooks tend to distort and fail before the chain breaks, and some claw hooks have a very shallow slot, making them more likely to fall off. Also, be aware that hooks can become uncoupled if the chain slackens when the load settles during a journey.

But there is good news for operators because many equipment manufacturers provide transportation guidelines in their operator’s handbooks, similar to the example taken from the Volvo L110-L120H wheel load handbook.

There is often a wealth of valuable information in the corresponding tables that provide the number and size of chains required and the correct tie-down points for the machine.

For more information download the latest Load Restraint Guide.