Trailer arch & loading philosophy...

I have always put 4by 4s center, it makes trailers last but easy 2 have them fall off back if 2 much # is put in center on rough roads

 

Depends on how heavy the load is. Some long loads won't flatten out the trailer. If the arch is still in there, there's a better chance of the dunnage walking if you put it towards the middle.

 

Gotta have enough height in the middle for the loader to slide his forks out. Otherwise I'll strap/chain the trailer to the I-beams/pipe or vice versa, whichever bends easiest.

It rides rough with rigid beams and a big space in the middle with no dunnage because trailer doesn't flex at all. All the weight in the middle and you'll lose end dunnage.

Found a happy medium with my Renegade, 3/4" plywood on top of the 4" timber on the front and back and just timbers sans plywood in the center works on rigid items like crane beams, etc. Used to use 2x4 on top of the 4x4 on the ends but that never seemed to work right.

 

a driver told me 2 years back.

trailers arch. so that when loaded. the weight flattens them out.

if the trailer were flat. the weight would bend them down.

the trailer i'm pulling. is arched. and it don't flatten out. but every trailer i've pulled before. did flatten out.

 

A deck trailers frame is a giant spring. It is arched because if you are loading a shorter object that is full payload weight in order to distribute said weight evenly it must be in the middle. Being a giant spring, it must flex, in order to accept the deflection properly it must be positive (arched). If it is negative the suspension components are not carrying their proper proportion of weight causing failure.

 

I don't think you focus on worrying about the arch other than to maybe keep end bundles propped up on the ends, and "tilted" toward the center of the trailer to keep sticks from walking out. Today trailer manufacturers brag on a trailer being able to hold it's arch, loaded. I think outside of single coils or other small but very heavy object, the arch should be expected to be there. Loading long pipe or steel, I used the same dunnage boards front to back and let the trailer and product do whatever it wants to do. Just make sure you retighten after about 15 miles as the arch settles and maybe loosens the securement in some key places.

An exception to this is perhaps structural engineered wood beams and in those unique cases, the loader will typically put down the appropriate dunnage as he sees fit depending on trailer type, product length, and arch amount.

 

If you care at all about the life of your trailer, then yes there is a correct way to load your arched trailer. If you care at all about the product on your trailer, then yes there is a correct way to load your trailer. There is no real "blanket answer" though, as each load is unique. Most guys today don't use enough dunnage when hauling heavy steel loads for example. Think about how much weight you are putting in one 4 inch spot. I suppose most folks are talking about their company trailers that they just don't care about though. Sometimes the product itself needs to stay flat. As mentioned earlier, generally folks use whatever dunnage required for unloading (big forklifts require bigger dunnage) in the center of the trailer, then work out from there typically supporting every 8-10 feet or so.

 

when hauling rigid products such as beams or pipe, any spring in the trailer deck itself is gone after the load is secured. What I always did when pulling highly arched trailers was kept approx. 3"x4" dunnage. use a combination of it putting it 3" high in the middle, next two out 4" high, outside ones use 2- 3" on top of each other or a 3" on top of a 4". Just try to shim it up so the load distributes weight to each piece of dunnage. You can eye it up from behind the trailer before loading. It doesn't have to be perfect, but you have to make sure none of the dunnage is loose under the load. Then you always want to place your chains close to the dunnage to clamp it down.

I guess doing it this way most of the weight winds up sitting on the ends and your chains in the middle are sort of pulling the trailer up against the load. I think that's what you want.