trailer frame?

mikehaugen · May 26, 2011

I have access to some 4"x6"x1/4" rectangular tubing and an old crappy trailer with 2 good 7k axles and was considering building a new trailer. Does anyone have any thoughts on this as a mainframe? I know that 10" or 12" i-beam is usually used but this is free. I want to make the frame 20' (including a 3' beavertail) and would prefer a gooseneck (obviously heavily gusseted around the front). I don't know if the tubing has a high enough profile to be stiff enough. Maybe I should consult an engineer, but thought I would ask here.

jmanatee2 · May 26, 2011

what do you want to carry for weight? 14k?

If I am using beam boy correctly....(new to this app) With 14k on the trailer evenly distributed ( I know it wont be ) ( I did 825lb per ft from 1 to 18 ft so 17 *825 is about 14025lbs..

With the axles at 11' and 13'

With two rails (each side 6"h 4"w .25" thick) I get a maximum deflection of .20" at the 20' mark..... Maximum stress of 15ksi at rear axle.

See photo. Hope this helps

mikehaugen · May 27, 2011

Thanks for that jmanatee2, as far as weight right now on my other 20 footer I just put my jd 1070 with an attachment and the occasional car or truck. It is only a 7,000 lb trailer and works fine for that weight wise, but it is narrow and want to build a flatbed and like I said I have the two 7k axles so would like to build the trailer to utilize them. Right now my 3/4 ton ram gasser has no business pulling 14k, but have plans to buy a 1 ton diesel next and so it would be nice to have the extra capacity.

pat32rf · May 28, 2011

My "big" trailer started life as a 10meter sailboat trailer. Two 7k axles, two main rails that bend in to a 2.5" extendable tongue. I've removed the bunks and decked it in with 2x10 hemlock but the frame is original (about 35yrs old).
The main rails are 2x4, 1/4" wall. Its not a goose neck, but spent a few years hauling Dad's big skid steer and small crawler. Now it hauls my 6000lb of JD and is still A1....
The actual flatbed section is long enough for a full length pick up truck wheelbase with six feet of open frame in front before the two side rails join at the tongue.
I think 2x6 should be fine if done right...