What is the reasoning behind WLL requirements?

you don’t seem to be accounting for the friction the weight of the machine alone causes with the deck. Add that to the chains pulling back and you are sufficiently secured for all but a catastrophic collision involving a sudden stop. At that point the forces are so high most securement is going to fail.

 

Only an issue if you don't pull the opposite direction.

 

In my opinion ...
Well let's word this different.
What I try to do is
I look for a 20-30 degree angle , preferably a 30 .
I do not like a 45 degree angle .
Yes everybody does it different and everybody has their opinions.
This is what I do .
My reasoning is that is the safest / stongest angle to prevent forward / backward movement .

 

The .8 refers to breaking strength not WLL, the requirements for WLL are .435 in a forward direction which 13.2K would cover.

 

That's what I assumed. Because indirect tie downs force both sides down, it's like a direct tie down on each side. Seems like the biggest benefit is the forced friction with the deck....
Also, to build on the MBS. The WLL is what the equipment can continually handle, without over stressing. If you happen to be an audiophile, ita like RMS and Max wattage.. it may be designed to take X as a sudden hit. But at Y it can run continuously.

 

Late to the party as usual but here's the rule I use and it has nothing to do with the regulations. If you loose a piece off a load the chains hanging on the rack and straps in the box did you no good.

When I was in the motorcycle industry I hauled 20-24 one of a kind custom motorcycles all over the country to bike shows and the man who trained me told me that if a bike got damaged in transit and there were straps still hanging on the rail, it was my fault period.

A piece of securement, be it a strap, chain, binder, ratchet is doing nothing to protect you, your load and the people around you if it's hanging on a rack or in a box. Of course there's no need to use everything but there's no excuse for not using enough +1.

 

Exactly you will be cited for being under the minimum securement faster than for over securement!
I frequently haul stand up coils they are 28 inches wide and 7 feet tall . They weigh roughly 14k (aluminum) I usually have close to 20k securement on each one. Mainly due to the narrow foot print of the coil,, I am not comfortable with any less

 

That’s only 2 straps. There room for 3