The Basics About Ratchet Tie Down Straps
The ratcheting tie downs are the assembly of tie down webbing and ratchet buckle , it’s a well recognized fact, if we use cam buckle instead of ratchet buckle then it’s cam buckle tie down, it’s pretty straight forward, isn’t it? Due the low strength of the cam buckle, we usually see these cam buckle tie downs being used on pick up trucks, 1” cams are all over the place while 2” cams are being used in box trucks. 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, 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.
As of now what we described is the tie downs for flatbed or similar commercial vehicles, there are another category of ratchet straps for semi trailers, ratchet e track straps , these tie down devices will be used with E Tracks installed inside the semi trailer. By estimation, there are almost 80% trucks on the road are box trucks, so these e track straps are supposed to the most popular ones by volume. And these straps are not as strong as the one we use on flatbed truck, the working load limit of typical e track straps is 1,000lbs, with minimum breaking strength of 3,000lbs. 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.
In first paragraph we talked about design factor of ratchet tie downs, which is 3:1, so the working load limit is 1/3 of maximum breaking strength for ratchet straps, 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. The most common materials in making tie down webbing are nylon and polyester, which serve different tie down applications. The typical application for nylon webbing is motorcycle tie down, while polyester webbing is ideal for tying down concrete pipes. Elongation, tensile strength, abrasion and environment, these have to be taken into consideration when making tie down strap. Breaking strength has to reach the recommendation level no matter what, and elongation has to meet the requirement, abrasion and environment sometimes are not that clear cut, when designing tie downs we may have to consider the most extreme conditions these tie down straps may be in, or we may just consider the normal transportation environment.
