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Building a trailer
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Posted by: bear207

02/11/2007, 10:17:04

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I am looking at building a trailer. I purchased a plan for a 6' by 16' trailer that I am sure will work but I get the feeling I could build it as strong with different materials which cost less.

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The trailers I see around here use a v shape made out of c- Channel at the front, which the ball coupler attaches to. The plan uses a square tube, which runs from the rear of the trailer to the front and extends out 4 feet which is braced by 3 x 2 x 0.125 rectangular tubing and the coupler mounts to the end of the square tube.

Also the plan calls for 5 x 2 x0.188 (3/16") rectangular tubing for the side rails, which the axles mount to. I have checked out a few trailers around here and all of them use a 5" @ 9 lbs or 5" @ 6.7 lbs I can't tell without measuring the width of the channel.

The other thing I am in question about is they use a 3" @ 4.1 lbs channel for the front and rear "bumper" the trailers I looked at used the same size channel as the sides for the front and a 6" X 2" X ? Rectangular tube on the rear.

I don't want to play around with the design too much and mess up the axle placement and weight ratios etc. but if I use there design I will be using a lot more material and it will cost me more.

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So my questions are:

-Would 5" @ 6.7 lbs. be sufficient for the side rails. Compared to 5" X 2" X 3/16" tubing which weights 8.15 lbs/foot loose 46 lbs. this way and save $80 in price.

-If I go with a two link front made of 5" @ 6.7 lbs Channel instead of the 3 link made of 3 X 3 X 3/16" square tube braced by 3 X 2 X 1/8" rectangular tube, would I have the same strength?

-I know the front and rear cross members/ bumper will be fine with a larger piece of channel on the front and rectangular tube on the rear. I want to just put channel on the front and the rear.

I know the drawings are crude. Any help would be appreciated.







Modified by bear207 at Sun, Feb 11, 2007, 10:18:38


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Re: Building a trailer
Re: Building a trailer -- bear207 Post Reply Top of thread Forum
Posted by: bear207

02/15/2007, 00:29:41

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So...back to my question, which tongue design is superior? I understand the dangers in skimping to save money. I also believe in practicality.







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Re: Re: Building a trailer
Re: Re: Building a trailer -- bear207 Post Reply Top of thread Forum
Posted by: randykimball

02/15/2007, 01:14:08

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I like to have a stout, non-spliced, member down the middle of the tongue through the front bulkhead to at least the second cross brace.
That provides vertical support.

Then I prefer to have an angled brace from near both corners to the tongue at an angle that fits the angle designed into the pre-fab tongue hardware on the shelf (the ones made to fit over these braces. I then make the tongue length a factor of this angle and a length that allows for maxinum jack-knife letting the corners of the trailer miss the bumper or tail lights. I want these braces to be the first thing the bumper or tail lights will hit. I then brace these braces again back to the bulkhead at the likely contact point. These cross braces in this configuration provide horizontal strength and a stable tow. This is important to kill harmonics that can begin to generate at the horizontal flex in the forward tongue. Such harmonics can induce osolations that will wreck a trailer and tow rig in a down hill emergency.
Also note: ... never pull a trailer of any reasonable weight with a dealer installed bumper stabed trailer ball. Those things have far too much squirm and the above problem is a sure bet. Records will witness this problem by the thousands.





The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

Modified by randykimball at Thu, Feb 15, 2007, 01:28:23


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Re: Re: Re: Building a trailer
Re: Re: Re: Building a trailer -- randykimball Post Reply Top of thread Forum
Posted by: bear207

02/16/2007, 19:30:51

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Thank you for the information. You were very helpfull. I understand now why you would need a center member on the tongue.

Thanks again.








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Re: Re: Re: Re: Building a trailer
Re: Re: Re: Re: Building a trailer -- bear207 Post Reply Top of thread Forum
Posted by: randykimball

02/17/2007, 00:53:39

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you are quite welcome, always is nice to hear one helped in some small way.




The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.


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Re: Building a trailer
Re: Building a trailer -- bear207 Post Reply Top of thread Forum
Posted by: Kelly Bramble

02/12/2007, 08:56:23

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Your trying to save $80? Less weight/mass means less strength in that structural shape with the same material. You would need to run the statics to see how this fits into your weight handing requiremments. I hope there is a atructural analysis included or rating with this design.

I suspect you will put twin axles under this frame. Standard OEM axles are rated at #3500 - double check the axles you are planning to use.

Remember, for structural designs, it is a lot easier to over design than to save a nickel and design "just right".







Modified by Kelly Bramble at Mon, Feb 12, 2007, 08:56:53


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Re: Re: Building a trailer
Re: Re: Building a trailer -- Kelly Bramble Post Reply Top of thread Forum
Posted by: randykimball

02/13/2007, 20:11:53

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Also, when building trailers you don't just build to handle loads, you must build to handle the "what if" factor. The machine towing the trailer has a human life in it. $80 dollars saved that takes away any "what if" may not be worth it.

Trailer tongues take a huge amount of abuse. They tend to get jambed up in backing "jack knife" mistakes, rammed by non-experienced drivers backing up to them, banged on unexpected bumps in the road, the list goes on. Never skimp on the tongue. Over the years I've designed and built several trailers, and have recieved MANY repeated thanks.. I owe each and every thank-you to the following facts:
1. Every trailer was designed with a "safety first" attitude
2. Every trailer was designed to be easy to handle and operate
3. Every trailer is very strong in the tongue
4. Every trailer design is slightly over built
5. Every trailer is well balanced,(towing quality braggs are numerous)
6. Every trailer accomplishes the intended task some better than requested





The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

Modified by randykimball at Tue, Feb 13, 2007, 20:33:02


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