The well recognized fact is that the assembly of tie down strap and ratchets usually called ratchet tie down, by this logic the cam buckle strap is just the cam buckle with tie down strap, why I am not surprised? Most likely these cam buckle straps are used on pick up trucks or passenger cars for luggage tie down, and small cam buckle(1”) are more popular than big ones(2”). Ratchet buckles are different, there are 1” to 4” ratchets, and they can be quite heavy duty and can stand all kinds of abuse, the most commonly used on commercial trucks are 2”, 3” and 4” ratchet tie downs, 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.
Of course what we discussed above is mainly for flatbed trucks and some other kind of vehicles, there are another category of ratchet straps for semi trailers, ratchet e track strap , these tie down equipment will be used with E Tracks installed inside the semi trailer. 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. the low working load limit of e track straps stems from box truck wall provides support for the loads inside the truck, come to think of it, the loads won’t fall off the bed, not going to roll over, it’s much safer than the cargo out there on the flatbeds, therefore low strength tie downs can be used to secure the loads. Coupled with e track cargo bar, rope tie off, e track hardware(such as D ring with E fitting), shoring beam, e track tie downs can be used to secure any kind of loads, and secure them reliably, but you still have to pay close attention to the safety of your cargo, easy to secure is not an excuse for careless tie down practice.
As we mentioned in the first paragraph, the design factor of ratchets is 3:1, that means the working load limit is 1/3 of the minimum breaking strength, in the mean time the design factor of grade 70 tie down chains is 4:1, so the chains can support heavier load, and are more resistance to abuse, such as high/low temperature, moisture, while tie down straps usually only work well under normal condition. The most common materials in making tie down webbing are nylon and polyester, which serve different tie down applications. Nylon webbing has better elongation than polyester, so for shock absorption wise nylon is ideal material while polyester usually is used to make tie downs for heavy equipment. Elongation, tensile strength, abrasion and environment, these have to be taken into consideration when making tie down strap. When making tie down strap , manufacturer has to follow the recommendation of breaking strength and elongation requirements, when it comes to abrasion and environment, there are much more variations to be considered.
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