The ratchet straps are just the assemblies of ratchet buckle and tie down webbing, by this logic the cam buckle strap is just the cam buckle with tie down strap, why I am not surprised? Cam buckle tie downs are only for light duty use, and 2” cam buckles are the biggest size we will see in the real world use, and it’s still light duty. Unlike cam buckle, ratchet buckle are much stronger, and 2”,3” and 4” ratchet buckles are used in industrial grade applications, such as heavy duty transportation, they have working load limit of 3,333lbs, 5,400lbs and 5,400lbs respectively, these assemblies have design factor of 3:1, thus the minimum breaking strength is 10,000lbs, 16,200lbs and 16,200lbs respectively.
Up until now what we talked about is the tie downs for flatbed or similar commercial vehicles, in reality semi trailers are much more than flatbeds in numbers, since they are box trucks the tie down needs are different, you will see most box trucks have E Track installed and use logistic straps. In fact semi trailer has much bigger share than flatbed truck, the percentage maybe around 80%, of course this is only estimation but you get the idea, and the conclusion is that e tack straps are by far the most popular tie downs. The e track straps usually have working load limit of 1000lbs, which is only 30% of the 2” flatbed tie downs, and the breaking strength is only 3,000lbs based on design factor 3:1. It’s easy to understand that why e track straps are not as strong as regular ratchet tie down straps, inside the box truck the loads already have strong support, at least there is no risk of falling off, all the e track straps will do is to fixate the loads more than tie them down. You also have e track cargo bar, decking beam, rope tie off, etc. at your disposal, with e track ratchet straps you will be able to secure any kind of cargo , make the trucking experience much more enjoyable , but keep in mind that no matter what you can’t be more careful than it should be when it comes to your important cargo and truck , make sure your load are secured properly by appropriate tie downs.
As we described in the first paragraph, the design factor of ratchet assembly is 3:1, that means the working load limit is 1/3 of the minimum breaking strength, for comparison purpose we know that the binder chain has a design factor of 4:1, which basically says that for the chains the working load limit will be 1/4 of their breaking strength, which indicates that tie down chains are designed for tougher environment than tie down straps are in. Nylon and polyester webbing are used in making tie down webbing, for different applications people will choose different material accordingly. Polyester webbing is almost perfect for tying down logs while nylon webbing is for small and light cargo. Elongation, tensile strength, abrasion and environment, these have to be taken into consideration when making tie down strap. There are mandated criteria for breaking strength and elongation of the tie down strap, while the abrasion and environment are mostly estimation and subjective sometimes, different area may have different requirements. Therefore the manufacturer may have to make these tie downs to different standards.