Framing for trailer floor

[flick]

I am getting everything together to start building my trailer, and I was looking for opinions on the sub floor framing for the trailer. I have seen most use a standard ladder setup, and was thinking about going that route, but now I have seen this:

Are there any advantages of using this kind of sub floor? Would it be a concern with using 1.5"x1.5" for the sub floor, over using 2x3 like is used for the rest of the frame?

 

[Detour]

i havent seen that before... might be getting fancy on ya!

something i might do is find a way to save on weight. i have noticed guys building trailers that could be rated for 10k instead of 3.5 or even 1k....

for me a lighter trailer would be better i think.

 

[R_Lefebvre]

I'm not sure what the point of that is, and frankly I don't like it. I think a "normal" floor frame would be better.

 

[ntsqd]

I think the good idea got lost in the execution. Done right diagonals would add some torsional strength. Done with interrupted stress flow paths like that and I'm with Rob. I don't see much point. Even if the diagonals are done well I'm not sure that you'd gain enough torsional rigidity over a 'normal' stringer layout to make it worth the effort.

 

[flick]

Thanks, what about using 1.5"x1.5" for the sub floor, over using 2x3 like is used for the rest of the frame?

 

[1x1_Speed_Craig]

I'm interested in this topic, as well...subscribed.

I'm using an '05 Tacoma bed for the bed of my trailer. I'm wondering if three (3) 2" x 3" crossmembers is overkill. The outside frame rails are 2" x 3" x 1/8".

Craig

 

[R_Lefebvre]

Flick, I would think 1.5" would be fine, depending on the load. Assuming this is a typical camping trailer, no problem. If you want to carry a 900lb Harley Davidson, maybe not. The actual flooring you are going to use will factor into the spacing required on your supports.

My floor supports are 2x4 as is the rest of the frame. But the floor supports on mine are heavily structural due to the use of split rubber torsion axles.

 

[walking eagle]

going diagnol certain would help with the trailer twisting, though as said, that layout seems to be missing something.

I'd use 1.5" even if I was carrying a 1,000lb Harley - it's just a matter of having enough stringers to support the load floor, and fewer of those are needed the stronger the floor. If you're floor is going to be 1/4 plate you wouldn't need as many stringers as 1/8" - or for wood, if you're going to use 1/4" you don't want your spans between the stringers to be as far apart as 3/4" plywood.

It also makes a difference what you're going to carry. If you're going to carry a uniform weight, you might not need as many stringers as if you were carrying the same ammount of weight over a small area. Like carrying a 900 lb ATV vs. that 900 lb harley. The harley's weight is all concentrated on two smaller wheels and will bust through a 1/4 sheet with the same stringers that might hold the atv for years of service.

 

[Titanpat57]

I think the good idea got lost in the execution. Done right diagonals would add some torsional strength. Done with interrupted stress flow paths like that and I'm with Rob. I don't see much point. Even if the diagonals are done well I'm not sure that you'd gain enough torsional rigidity over a 'normal' stringer layout to make it worth the effort.

I agree completely.

I have to look at that picture and ask...."why"?

If your welds are sound and ample, and your sheet connection to the floor beams are ample, outside of looking cool, I didn't see the purpose of this.

Make your life easy and run them traditional, and if you really live on the edge...put 45 degree gussets at the corners.

 

[R_Lefebvre]

I have to ask, who's trailer is that?

I think the diagonals could work, and might make the frame stiffer for twisting. Not that a trailer has many twisting forces because it's a tripod, but anyway. The big failing of that floor structure is just that many of the tubes dead end into another tube. If they'd all gond straight into the frame, it would be better.

 

[indiedog]

Seems like a lot of the supports in that design transfer their load to other supports. This only intensifies the load onto those fewer members and therefore the welds/connections.

There's a reason typical floor structures are the way they are; an equal distribution of the load with fewer connections and direct transfer to supporting structure meaning efficiency in materials etc.

If I was carrying a point load ALL the time then I'd look at an alternative to the ladder frame, but not for a general use trailer.

My .02

 

[805gregg]

The strongest most stable structure is a triangle, look how many there are there.

 

[R_Lefebvre]

That's a joke right?

Those triangles aren't that strong.

 

[indiedog]

A triangle is strong for bracing or loads along the plane of the triangle. The triangle has absolutely no strength (same for any other 2D shape) when the load is placed orthogonally or on the face. It is the method of distribution of that load that is important.

If you analyze that layout all the load placed on the two larger cross members is transferred to the four smaller corner members. Therefore 100% of the load is taken by those four members and 8 welds. That can't be good. I'd say those internal diagonals will pick up around 80% of the load which is then transferred through only 4 welds to the corner members. Again not good.

What's with the axle/suspension on that thing? Is there some reasoning there for the floor structure?

 

[Titanpat57]

:Wow1:orthogonally:Wow1:





well excuse me for livin'.........lol