Square Channel vs C Channel

My dilema
I did poorly when it came to math... I now regret not trying harder
I need to make a special purpose 25 foot trailer which can not appear
heavy duty.
Typically a 15,000 pound capacity trailer would have 6" C Channel
(frame) with 6" Junior I Beams (cross members) spaced 18" apart.
I am proposing that we use 4" square tubing for the entire frame
structure with cross beams spaced at 12"
Is this frame as strong as "typical" or stronger.
An additional thought: several manufacturers do what they call fold
back trailer tongues... essentially they double the beam from directly
in fron of the tires to the tongue...
Reply to
anderson2624
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"anderson2624" wrote in message news: snipped-for-privacy@homeimprovementbanter.com...
If your metalwork can't look heavy-duty- make sure your lawers do. Not a good thing to whip together without proper engineering. Not bashing you at all. Honestly- Trailers are so dangerous it's scary seeing a hooptie looling one near me in the car in traffic. I get WAY in front of him.... I'd rather take a speeding ticket than a body bag any day.
Rob
Rob
Reply to
Rob Fraser
On Mon, 4 Feb 2008 08:30:58 +0000, with neither quill nor qualm, anderson2624 quickly quoth:
It's against the law to cheat the DMV, boy. Besides, any inspector worth his salt could instantly tell that your "toy" was built to carry a tank or two by looking at the springs and frame.
-- Our greatest glory is not in never falling, but in getting up every time we do. -- Confucius
Reply to
Larry Jaques
A 15,000 pound capacity trailer is not one to start out doing calculations on. Too many point loads, too many flex loads, too many fatigue loads, too many off center loads. You ask if you can use 4" square tubing; there are lots of 25' and larger special purpose trailers made with 4" tubing, go to any boatyard with the 22' and larger boats. Can you make one that fits your needs from 4"? Who knows.
You posted earlier, no one here wants to touch your question. None of us wants to stick our collective necks out for that big a project. Too many unknowns, too much of a safety risk.
anders> My dilema
Reply to
RoyJ
6" C channel @13#/ft is ~20% stronger than 4" x 1/2" wall at 23#/ft.
Reply to
Mechanical Magic
"Rob Fraser" wrote
I agree, except when I see some nitwit on the highway, I usually try to keep them in front of me so I can keep an eye on them. Unless there's enough space that I can kick it up to 85 and get far enough ahead to be safe. I speed up to pass semis, after having three lose caps while right behind them, or beside them. Easy to do with the turbo Cummins.
Trailers take so much flexing. Over every bend and sway and pothole and driveway entrance. Even the good ones stress out and fail.
Anyone towing ANYTHING needs the trailer to be from two to three times the capacity of the weight being towed. Just my opinion after seeing a lot of them in the ditch and into abutments, guardrails, and other motorists. I have met morons at the gas station that say their F150 will tow a 10,000# trailer just as well as my Dodge. And they got some three story seven slide out trailer hooked to it. IIRC, my Dodge is rated at 14,600, and 10,000 is about all I'd want to hook it up to.
YMMV. And probably does.
Steve
Reply to
SteveB
Define 'stronger'?
Mechanical Magic wrote:
Reply to
RoyJ
4" by 1/2" wall tubing is a little bit heavy...
i
Reply to
Ignoramus31218
i, Yep, sure is, but still weaker.
To get a 20% increase in "strength" a 4" square bar will do it. At 53#/ft.
However the added total gross capacity of 3000# will be offset by the added weight (2000#) resulting in a net gain of 1000#.
I didn't say it was a good idea, just answering the question.
Reply to
Mechanical Magic
And it would be as floppy as a wet noodle. No stiffness.
Mechanical Magic wrote:
Reply to
RoyJ
A "little"? That would be as heavy as 5" drill pipe. Why not just use SOLID? Or railroad rails?
Steve ;-)
Reply to
SteveB
railroad rails are not considered good for structural purposes like this. Every time a train wheel rolls over them, they get strain hardened making the rail very brittle.
Reply to
desperado

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