The ratchet tie downs are the assembly of tie down strap and ratchet buckle , it’s a widely known fact, 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, with 3,333LBS, 5,400LBS working load and a design factor of 3:1, these ratchets have 10,000LBS and 16,2000LBS breaking strength respectively, which are pretty strong for most tie down applications.
So far we talked about tie down devices for flatbed trucks or similar transportation 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 semi trailers have E Track installed and use logistic strap . 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. With 1,000lbs safe load limit and 3,000lbs minimum breaking strength, e track straps are not as strong as flatbed tie down straps, It’s understandable that e track straps have lower working load limit, because the box truck wall will provide strong support for the loads inside, and the truck wall will prevent the loads from falling off, rolling over, tilting and some other dangerous movements. With the help of e track cargo bar, rope tie off and some other e track tie downs and accessories, it’s pretty easy to secure loads inside the box trucks, but easy doesn’t mean not important, you still have to look out for any risks may present in the process of transportation, so secure your loads as reliable as you can, use the right tie down devices for your job.
We already discussed the design factor of ratchet straps, it is 3:1 and for the record all this says is that safe load limit of tie down straps is 1/3 of it’s breaking strength, while grade 70 transport chains which have a design factor of 4:1, that means the transport chains will work in more tough environment than tie down straps, which usually are chose for regular loads. 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. There are mandated criteria for breaking strength and elongation of the tie down straps , 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.