Indirect, and Direct Securement
 

I put this here for the new guys to learn someething as I did today.

I received a WLL (Working Load Limit) violation today, that put my trailer OOS (Out of Service) for 1 hour.

This is due to my using direct securement instead of indirect securement. Now my little green book is condensed just a little two much, and it doesn't say anything about this. The big book that the DOT has explains it much better. Direct is going straight from one side of trailer to same side of load. Indirect is using both sides of the trailer for securment.

The rotomill that I haul, can be secured by just using ratchet binders, and not using chains. I went from track to side of trailer, like the other experienced drives have done. Come to find out this reduced the WLL in half.

According to what MT DOT has in the computer the Cat PM-565B weighs 83600 lbs, with Aggragate WLL required is 41800 lbs. I had 4 13,000 lbs WLL tiedowns and one 5400 lbs binder. This equaled 31400 in WLL, being hte one binder was indirect securement. The 4 binders were only good for 6500 due to not using both sides of the trailer. I was lucky enough to have 2 extra big binders to put on making it legal.

Has anybody heard of direct and indirect securement? It through me for a loop when it was brought up.

TMC touches a little on the direct securement dilema during orientation. It is very confusing and you did about the best job of concisely explaining it that I have seen.

They figure the Working Load Limits of securement devices assuming that you will be using a strap or chain from one side of the trailer, up and over the load, and attached to the other side of the trailer. In theory you then have TWO chains/straps pulling down, one on each side, even though it is the same chain/strap.

When you just hook the binder between the load and trailer you need two, one on each side at the same spot, to do the same amount of securement as one binder and one chain would do.


I believe that this is based more on some physics than common sense. Thank you for bringing this up, as I haven't thought about that direct/indirect issue for a while.

Although, it has been a few years since I've pulled flatbed, I can't say that I have EVER heard about direct and indirect securement. But, somehow, I get a sense that someone is working with FLAWED SCIENCE.

It depends on the angle of the chain/strap going up from the edge of the bed. If the load is low and in the center of the trailer, the lower the angle of the securement, the less it will hold. Much like power lines. It really does not take a lot of ice to break them in winter. If the wires were hanging straight down, it would take far more weight to do that. The more perpendicular to the edge of the load, (the more parallel to the bed) the less force it will hold, and the greater tensile strength it will need to hold the same load. That's why a lot of the power lines I've seen are "COPPER JACKETED STEEL", because steel has the tensile strength that copper does not have, but the copper conducts the current far better.

However, if you do not want to load to shift, you must secure BOTH sides in about the same places. Just one binder on one side generally does nothing to keep the other side there. Whether it's a strap over the top or a chain to each end of an axle, you can not simply pull one side over to the bed and expect the load to stay there.

Yeh...Thanks for bringing it up. :D Sorry about the "violation" :sad:

I did a search and only found people wanting to sell me stuff...

Is there a site, book, info that shows the "proper" way to tie stuff down? I make sure the load is stable and then secure it to the what my "common sense" dictates. BUT I realize there is some $%^&&$#$$$$$ out there with no common sense ready to write me a citation :evil:

Well Fourcats the government info is some help:

http://www.fmcsa.dot.gov/rules-regul...vehicle/cs.htm

Take everything the Gov't tells you with a grain of salt though. Remember if you get it wrong because the gov't told you wrong then it is your fault. Of course if the gov't gets something wrong and you told them wrong it is also your fault. :wink:

To much securement is always better than to little securement.

Also it depends on the Officers interpritation ! And the one at the scale in Oklahoma on the 40 miles you have to go thru on 287 is real narrow. I had on a 60,000 piece of oilfied "something" that couldn't have chains over it so I put 9 4 inch straps over it then two 3/8 chains in front of and behind the legs to stop it walking. By my math I had almost 3 times what I needed. Got a ticket as he said, no matter what the tag on the strap says, in Ok. a 4 inch strap is good for 4,000 lbs, a 3 inch strap is good for 3,000 lbs etc. Said the two chains didn't count as they only prevented movment for and aft not holding the load down.

Thanks for all the insite. I don't know when I'll pull the mill around again, cuz they needed the lowboy back in Fargo.

It was all learning experience, may not have all been good, but I must be lucky, since it didn't cost me anything. Must pay to be nice, and be willing to learn.

Your own attitude can make all the difference in the world. Thanks for sharing, this is obviously something that isn't general knowledge, or at least not used on a daily basis.

Reb-