The Trailer Frame

[xe1ufo]

Here in Mexico they sell a square tubing used for a lot of smaller industrial structures. They call it PTR. With 470 factories in our town, I can buy it by the kilogram at the junk dealers. Is this stuff any good as the basic bottom trailer frame and tongue? For the lighter weight 4 by 8, what size is good, if any?

I am thinking of a frame that will withstand our bad roads and also the many non-paved roads we frequently travel.

Thanks in advance!

[Chris C]

There are differeing opinions on that subject, but in my opinion, 2" x 2" x 1/8"wall is a suitable tubing for a tear. Some will say that is overkill, but if the roads are a poor as I imagine you will be using, I think you'll need it.

[xe1ufo]

Hey Chris:

Thanks! Oh, and I have much gratitude for Norman, Oklahoma. My missionary parents met there in 1954 ...

[Chris C]

Nice little college town. I moved here 6 1/2 years ago after living just North of here in Oklahoma City all my life except while in the Military. Like this little town. I live out in the country on 6 acres and would never move back to town. In fact, I'd love to live somewhere where the nearest town didn't even have a stop light!

[cracker39]

My NT utility 4x8 utility trailer is constructed of 1 1/2"x3"x3/32" "U" channel and is rated for 1180 lbs GVW. Since my Squidget shouldn't weigh more than 1400 lbs loaded, I think 2"x2"x1/8" should be plenty strong enough. I'm using 3"x3" x 3/16" for the single piece tongue with two 2"x2"x1/8" side braces to help support it.

Dale

[angib]

My NT utility 4x8 utility trailer is constructed of 1 1/2"x3"x3/32" "U" channel and is rated for 1180 lbs GVW.

Dale, thanks for those measurements - I've added them to my tongue strength page so I hope they're accurate.

Incidentally, as your 3" x 3" x 3/16" tongue is off the scale, I've run the spreadsheet on it which gives a section modulus of 1.73 in3 - or 3.4 times stronger than a single 2" x 2" x 1/8" tube.

Andrew

[cracker39]

Andrew,

You are obviously quite an engineer, being able to make those stress measurements. By "off the scale," do you mean that the 3x3 is overkill? My one tongue piece will be approximately 4 1/2 ft, coming from the center of the frame, with two braces, one from each corner, joining the center piece about 3 ft from the frame. All 3 pieces will be welded to the front two cross members, but going only 10 inches from the front to the back of the 2nd cross member. You can see this new frame design at http://web.tampabay.rr.com/wdsummers/squidget2.html. I'm not sure if I should cut the center piece down from 3x3 to 2x2. What do you think?

Thanks,
Dale

[Guy]

Chris C wrote:

In fact, I'd love to live somewhere where the nearest town didn't even have a stop light!

I am from New York and lived in SoCal for the last 18 except for two years spent in Arrowtown, New Zealand in a ski resort. You had to drive 2 hhours to hit a stop sign and a little further on down the road in Invercagrill ,at the southern tip of New Zealand, you hit you first traffic light.

[angib]

Dale, I can't get this description:

My one tongue piece will be approximately 4 1/2 ft, coming from the center of the frame, with two braces, one from each corner, joining the center piece about 3 ft from the frame.

to match your diagram:



Where's the "one tongue piece"?

By off the scale for your 3x3x3/16, I just meant bigger than any of the sizes I had listed. Our host, Mike, likes to recommend the twin 2x2x3/16 tubes (ie, an A-frame) that he has on his chassis and your single 3x3 is only some 30% stronger.

Andrew

[cracker39]

Andrew,

As a former tech writer, I understand how easy for what you see in your mind to look correct on paper to yourself and be muddled to others. I’ll try to clarify. In the top view diagram, to the right, the main tongue piece is labeled C (3”x3”). The connecting 2”x2” braces are labled A, one from each corner to the tongue. They are welded to the tongue about 3 feet from the front cross member. These 3 pieces are the rightmost pieces in the diagram. As you can see, the front two cross members are separated by only 6 inches. This gives me only 10 inches of the rear of the tongue that can be welded to the two cross members due to the drop-down floor not allowing it to be welded any farther back, same with the corner braces. That is the weakest part of this setup. I may need some pieces of steel plate added between the center tongue piece and the two cross members for additional strength. I’ve undated the diagram again on my site, correcting the side view drawing to match the top view.



Dale


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[xe1ufo]

Dale:

Why do I get an empty box with an X in the corner for your two pictures? All we are expexting from you is perfection!\

[cracker39]

Dr. Steve, I don't know what you are seeing..or rather not seeing. Do you have the html disabled? I am seeing the diagram of my chassis in both posts from Andrew and myself above. It is linked to a jpeg image on my web site host via an html statement in our posts.

Dale

[xe1ufo]

I am not having trouble seeing anybody else'spictures. And yes, I have Hot Tamale enabled (This is Mexico ...) I really would like to see your wiring diagrams? May I have a link? Pretty please?

[madjack]

...xe, right click on x and select "view image"(or whatever your browser says)...you should now see pics
madjack

[xe1ufo]

madjack:

It still doesn't work. I will shut down and restart. Maybe try with the FireFox browser.

Thanks! What town in Lousianna are you in? We used to visit Homa, and Sulpher a lot.