For a GN trailer, can I put the planking right on the I-beams?

cjmdjm · Feb 9, 2012

I got a couple 38' long, 16" I-beams at a farm sale, and I want to build a 24' gooseneck trailer with them. I've noticed that most GN trailers are built with some channel iron above the I-beams to support the deck, like this picture:

http://i427.photobucket.com/albums/pp353/SLOWECO/32Ft_Goose_Neck/P8230079.jpg

I have some heavy creasote treated bridge planking, at least 3" thick, and I was wondering if I could just put these right on top of the I-beams, without the channel irons in between. I'd like to keep the deck as low as I can, since the 16" I-beams are already quite tall. Running them width-wise across the trailer, of course. The axles I have for the trailer are only 7500lb, not 10000, so I won't be putting that much weight on it.

Maybe I could also have some channel irons along the edges of the deck, with angle irons running diagonally down to the bottom of the I-beams, for support.

What do you guys think? Thanks!

Case485Guy · Feb 9, 2012

How far apart are you planning on the I beams to be? The biggest problem i see is support for the boards, even 3" thick. Hauling a small diameter heavy load would be not the best idea with a trailer set up like that. There was I guy that hotshotted at same company I had trucks leased to that built one like you describing, boards broke alot. Company finally deleased the trailer when a valve went through the floor, luckily he had belly wrapped a chain around the valve when tieing down.That kept the valve from hitting pavement, just kind of hung there until a pole truck got there to off load it,
Could go with a pierced beam and build convential to keep floor lower. Would be alot more work, but would be a very strong trailer.

cjmdjm · Feb 9, 2012

What is this pierced beam construction you speak of? Anything that would get the deck lower sounds good to me. I got a good deal on these I-beams, but I think they are plenty tall for the size of trailer I want to make.

The I-beams will have to be spaced fairly far out towards the wheels, since thats where the mounts on the axles are. However, I mostly plan on hauling tractors. The wheel spacing of my tractors roughly matches the I-beam spacing, which should keep the weight right on the I-beams. Most of the stuff I would haul that would put weight in the center (little narrow front tractors) is fairly small.

Thanks guys!

Case485Guy · Feb 9, 2012

Pierced beam is where you cut a hole just large enough for the C channel to slide through the I-beam. The top of the I-beam becomes part if the floor deck. I had a 40'er built like that,loved the deck hieght. The main beam was notched just big enough for the C channel crossmembers to slide through, then welded up after getting everything square. On top of the tires a metal plate was welded, could not run boards due to clearance issues. The rest of floor was board decking. Standing on top of the deck you would see the tops of your main I beam, the plate over tires and rest was wood deck.
Same design as the one your pic, just the C channel run through the I beam, instead being laid on top of I beam

Case485Guy · Feb 9, 2012

Check out a drop deck trailer on an 18 wheeler next time you drive by one, same concept

Tdawg · Feb 9, 2012

If I'm reading this right, you want to use these I beams for frame rails and then use boards for cross members/decking???? And you want to put a license plate on it and pull it down the highway??? How are you going to attach the boards-deck screws??? Carriage bolts??? And you want to put a tractor on top of it??? Think about it...would you want your family following this rig down the road???

Look, I'm new here and I'm sorry if I ruffle feathers, but I've spent a lot of years building and fixing trailers and you wouldn't believe some of the things I've come across. As strange as it may sound the roads are for everybody, not just guys looking for a cheap (and dangerous) way to haul their stuff around. If you want to build a proper trailer I'll be the first guy to help you out but not if you want to cobble something together out of stuff you have laying around in the yard.

Cheers,
Terry

cjmdjm · Feb 9, 2012

Edit: talking about the pierced beam construction here

That does sound good. You said that it would make a very strong trailer. But I would be a bit concerned that the C-channel is being supported by the center section of the I-beam. Maybe its just my I-beams. The top and bottom of my I-beams are quite thick, but the center (vertical) section is only a little more than 1/8", probably 5/32".

And the weight of the deck boards rests on the C channels, which are supported by the vertical part of the I-beam, which they stick through, right? About what size and spacing of C channels would you suggest? The trailer will have two 7500lb axles, and so needs to be strong enough for a 15000lb gross weight (24' incl. dove tail). I suppose if I use my 3" thick bridge planks, instead of lighter lumber, the C channels could be spaced a bit farther apart, right?

Thanks for your help!

Tdawg · Feb 9, 2012

"I" beams have a tapered web as opposed to "H" beams which are square. Trailer frame rails are shaped like "H" beams. The rails are slotted so that the cross members are the same depth as the thickness of the deck boards. Once the boards are attached they are flush with the exposed frame rail.

cjmdjm · Feb 9, 2012

In response to Tdawg, this is in the early brainstorming stage. If I had used my original idea, I would certainly have put in plenty of bracing between the I-beams.

I hadn't given much thought to fastening the deck boards down to the top of the I-beams. I guess I figured I would weld on some brackets which I could bolt the boards to. But please understand, if I couldn't come up with a very secure way to attach the boards, I would never have started building the trailer.

Thats why I made this post, to see if this idea was remotely feasible, before I wasted too much time thinking about it. I guess you have answered that question. I do want to build a proper trailer, that is sturdy and safe. If I suggest anything else that strikes you as unsafe, please say so.

Case485Guy's idea of pierced beam construction sounds good, it will get the deck lower than my original (misguided) idea anyway, and be much stronger. (See my previous reply about this).

Thanks for your help!

timster2 · Feb 10, 2012

You may have scored some impressive beams, however, do a quick calculation of the empty weight of all your components. You may end up with a very heavy trailer that you can't load your equipment on. And just a thought once you go over the 10k weight you need a class A license.