Cargo Securement With Ratchet Tie Downs: Use The Best
So far as we all know that when put ratchet buckle and tie down webbing together we get ratchet strap, when the ratchet buckle is replaced by cam buckle then you get the cam buckle straps. 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”). 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, the typical working load limit for 2” tie downs is 3,333lbs, for 3” and 4” which is 5,400lbs, since these tie downs have design factor of 3:1, the maximum tensile strength is 10,000lbs and 16,200lbs.
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 tie downs , these tie down devices will be used with E Tracks installed inside the semi trailer. In fact box truck 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 loads out there on the flatbeds, therefore low strength tie downs can be used to secure the loads.
As we described in the first paragraph, the design factor of ratchet straps 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. The typical application for nylon webbing is motorcycle tie down, while polyester webbing is ideal for tying down concrete pipes. When making the webbing, we have to take following characteristics in to consideration, the breaking strength, elongation, abrasion and the environment. 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.
