Does Tie Down Angle Change WLL?

Cargo Equipment Corp's website states that changing the tie down angle between the tie down and the bed changes the "effective" working load limit (WLL) of the tie down.

It reads as follows:

90 degrees 100% of rated WLL
60 degrees 87% of rated WLL
45 degrees 71% of rated WLL
30 degrees 50% of rated WLL
For example, if you are using a 3,333 lb rated strap at 45 degrees, the effective WLL would be reduced to 2,366.43 lbs.​

Is this just "practical advice" or is there actually federal regulation that dictates the relationship between the tie down angle and the WLL of the tie down in service?

If you want to see the link, it is here:

What is the Impact of Tie Down Angle?

 

I am not aware of any "Federal Regulation" that imposes WLL and angles.

Be it far from Truckers to be THAT smart to comprehend that level of understanding.

What I choose to see instead is a company that placed this information into your hands either through proven tests to failure at those angles or physics, science or whatever that came up with a adequate limitation imposed on a strap due to angles.

I for one don't have a problem with say 30 degrees at 50% of WLL. Just add more strapping. Or chain etc depending on what you have on your deck. I usually throw everything on the load. With the idea that a extra 45 minutes of work ensures the load remains on the deck should God bend down and play with the rig upside down. That thinking has saved me in the past in difficult moments where it's possible for that load to get loose.

Again, I accept this information and can use it as part of a overall evoluting to understand flatbedding better and by extension to be a more professional securement of loads that are difficult to be secured.

I do for one fail to run to dear Uncle Sam for regulating something that is already known. We should be able to teach this information to those who need it in the work with flatbedding rather than shove it down every students throats on the basis of Federal Regulating. We have too much of that crap already.

 

Legally? No. WLL is WLL.

 

Here are all your answers

https://www.fmcsa.dot.gov/sites/fmc.../Drivers_Handbook_Cargo_Securement_508CLN.pdf

 

You expect me to read?

 

The abbreviated version online seems to be TLR.

Now if half the straps on your load snapped and rolled the freight into a minivan burying them...

Liveleak.com - Panes of glass fall from truck and shatter on top of biker in China

 

Mainly I was just giving him a hard time. Some of these drivers can’t even be bothered to read street signs

 

Nobody wants to know because they have been doing it for years half-grassed...

 

I think the authors should change the wording, or language in that link. The point they are making is certainly correct, in that pulling at angles, much of the "force" is being applied horizontal instead of vertical, meaning you are applying less pressure vertically on your load. I think it would be a pretty tough thing to make rules or laws about it. But, I also think its a good thing to have in your mind as you are securing a load. Sometimes its more obvious than other times...

The crazy thing about that link though, is they keep referring to WLL. It sounds like they don't have a full understanding of what a WLL is. It doesn't matter if your angle is 90 deg, 45 deg, or 360 degrees... It has absolutely NO bearing on WLL. Working Load Limit, is simply a safety factor, which the manufacture (with guidance from the fmcsa) has determined is an appropriate margin of safety, over when the strap will fail. A 2" strap (generally speaking) has a breaking strength of 10,000 lbs. With the determined Safety Factor of 3, the Working Load Limit has been determined to be 1/3 of that 10,000 lbs, or 3,333 lbs. Whether the strap is 45 degrees, or 90 degrees, it will still fail at 10,000 lbs.... SF3/WLL, is still 3,333 lbs.

Working Load Limits or Safety Factors, are to account for the un-accountable. Loads shifting... Hard braking... Because nobody brakes the same, because nobody takes every corner at the same speed, there has to be an extra margin for safety added.

Under most conditions, OSHA has determined, that for over-head lifting, a Safety Factor of 5 must be used. For a hoist to lift a 1,000 lb load, it must be built to withstand a 5,000 lb load. The Ultimate Strength of the hoist is 5,000 lbs, but the WLL/SF5 is only 1,000 lbs.