Securing large loads in commercial trucking operations requires an understanding of the dynamics of the load while in motion and the limitations of the bindings used to secure the load. Forward motion of the vehicle, side to side forces, and gravitational forces all affect the stability of the load.
The North American Cargo Securement, or NACS, has established guidelines for load limits, the methods used to secure the loads, and the type of load binders used as a function of the load weight and dimensions.
Chain Grade and Size
The minimum size chains suggested for most commercial hauling operations is a Grade 70 (G70) chain. This chain type has a load limit from 3,100 lbs to 11,300 lbs depending on the chain link size. But the actual Working Load Limit, or WLL, of a binder assembly depends on other factors, most importantly the connecting mechanism on the end of the chains. Most popular for commercial trucking operations is a simple steel hook.
The method of attachment affects the WLL. A hook forged to the end chain link supports a lower WLL than a clevis style pin connection. Typically a clevis pin connection will carry fifty percent more load. Better still is the use of a heavy duty ratcheting binder which can support the highest load levels and approach the limit of the G70 chain itself. Ratchet or Level Binders have working load limits of 6,000 lbs to 10,000 lbs depending on size.
Forged versus Cast Components
The materials used for attachment devices and the assembly of the binder chain links themselves have considerable impact on their working load limits. In general a steel forged hook and link system is much tougher than a cast hook system. A cast part can become brittle and may break under extremely cold conditions. However, forged steel parts will stretch when overloaded rather than fracture. Regular inspection of your load binders for bent or stretched components will let you know when load limits have been exceeded and its time to replace them.
Proper Employment of Chain Binders
Apart from the materials of the load binders themselves, the methods of how they are employed are equally important. The NACS advises a minimum of four attachment points for single load items such as coils of steel, machinery, etc. The attachment points should have a maximum angle of 45 degrees to limit the range of motion.
In addition, the number of binders needed to secure a load is going to vary depending on the weight of the load and the size of the chain binders. In the table below the number of chains required to secure the forward direction of a load is shown as a function of the load weight and chain size. All chains in the table are Grade 70 chains.
Weight of the Item lbs 10K 15K 20K 25K 30K 35K 40K
G70 Rated Chains
Size Load Limit
¼ inch 3,150 3 4 6 7 8 9 11
5/16 inch 4,700 2 3 4 5 6 6 7
3/8 inch 6,600 2 2 3 4 4 5 5
1/2 inch 11,300 1 2 2 2 3 3 4
The ratings of binding systems and their employment is regulated by many organizations. The North American Cargo Securement, Web Sling and Tie Down Association WSDTA, and the Commercial Vehicle Safety Alliance CVSA monitor the commercial trucking industry and provide guidelines. But the Department of Transportation DOT, is tasked with setting the actual regulations haulers must follow.
Lauren Sawyer writes about science and technology and follows developments in the commercial trucking and transportation industries. She often writes about Grade 70 chain binder and fence privacy screen.
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