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A Question about building a trailer frame...

PostPosted: Tue Oct 18, 2005 10:48 pm
by RogerL
Was going for a Dinnete trailer but was given a truck slide-in camper and being a very cheap guy that I am, going to that on a trailer.
I need a 6'x14' flatbed trailer that will hold the camper in the back part and will hold my atv across the front. the gross of the two is about 2600lbs (fully load camper=1600 and the buggie=1000).
I would like to trailer to less than 1500 lbs empty and with a loaded tongue weight to be no more than 400lbs.
I just dont know which metal stock to use ie.. 3x2 box or 2.5 angle iron. Also not sure on the axle(s) yet, I perfer the older spring type.
Can ya'll help me.

Thanks,
Roger

PostPosted: Wed Oct 19, 2005 4:57 am
by bledsoe3
Look at Andrews (angib) post here. http://www.tnttt.com/viewtopic.php?t=5446

PostPosted: Wed Oct 19, 2005 7:15 am
by angib
Interesting! I'm guessing there's a cabover on the camper that makes a nice garage underneath it for the atv? You will remember to duck your head when riding the atv up there, won't you? :?

I don't think 2.5 angle is any good for a trailer of that size. Using a 2"x2"x1/8" square tube as the basis of comparison of strength, some results are:

2.5"x2.5"x1/4" angle - 4.0 lb/ft - strength 77%
2"x2"x1/8" square tube - 3.1 lb/ft - strength 100%
2.5"x2.5"x3/8" angle - 5.9 lb/ft - strength 110%
3"x2"x1/8" rectangular tube - 3.9 lb/ft - strength 180%
3"x1.5"x1/4" channel - 5.0 lb/ft - strength 227%
3"x2"x3/16" rectangular tube - 5.6 lb/ft - strength 241%
3"x2"x1/4" rectangular tube - 7.1 lb/ft - strength 285%

I've added in the 3" channel in case you prefer open sections.

Are you planning on always carrying the atv? Because if you don't, there's no way the tongue weight can be limited as you wish. My sketch of your plan looks like this:

Image

If the trailer contains 60 feet of steel at 5lb/ft, that's 300lb, so I can't see the whole thing weighing more than 600lb. Adding the weights you've given and some estimated centres of gravity gives this balance calculation:

Image

The thing to note here is that if you take away the atv (is it really 1000lb?) that 360lb tongue weight goes negative - the trailer will tip over backwards if not restrained and is completely unsafe to tow. Alternatives are:

- Never move the trailer without the atv on it.
- Build a 100 gallon water ballast tank under the atv platform.
- Devise some way to move (skid/winch?) the camper 3 feet forwards when the atv isn't there.

I hope this lot is useful! Beware - those centres of gravity are guesstimates - you really need to put the camper on a see-saw (is that a teeter-totter in the US?) to find out where's its centre of gravity is before you position the axle.

Andrew

PostPosted: Wed Oct 19, 2005 9:03 am
by Kevin A
I suppose one could always put two axles under the trailer, might be overkill but would reduce some of the tongue weight shifting problem.

PostPosted: Wed Oct 19, 2005 10:18 am
by RogerL
It would only take once forgetting to duck, to always remember to do so from then on. :lol:

The atv weights in 700 lbs empty. Plus about 120 lbs of cargo, then add to the front of the trailer, 75 lb generator, 2-5gal gas cans, and a spare trailer tire. so the front part weights in from about 1000 down to about 875. I can always add fire wood to balance out the load or take fancy rocks back home.

So, I guess the 3"x2"x1/8" rectangular tube would be the way to go for the framing for the trail and the tongue.

Thanks,
Roger

PostPosted: Wed Oct 19, 2005 12:04 pm
by angib
Roger, I reckon the 3"x2"x1/8" might be a bit light and I'd go up to the 3/16" thickness, at least.

And I, as an upright citizen, cannot condone fancy rock theft....... :lol:

Kevin, double axles won't help much. If they're leaf spring axles, as Roger wants, an equaliser would usually be fitted between the front and back springs. If they're torsion axles, it will reduce the effect, but don't you risk overloading one of the axles?

Andrew

PostPosted: Wed Oct 19, 2005 12:37 pm
by vairman
Well i guess you could make a adjustable axel like thay use on Semi trailers, This set up would allow you to vary the axel position depending on your load configuration...

Greg :twisted:

PostPosted: Wed Oct 19, 2005 12:46 pm
by Nitetimes
vairman wrote:Well i guess you could make a adjustable axel like thay use on Semi trailers, This set up would allow you to vary the axel position depending on your load configuration...

Greg :twisted:


Actually that's not terribly difficult, most of the larger boat trailers (and some small ones) have moveable axles on them.

PostPosted: Wed Oct 19, 2005 6:51 pm
by RogerL
The local hardware store has 3 X 3 3/16 for $2.29 ft or $1.89 ft per 20ft length. is that good?

PostPosted: Wed Oct 19, 2005 8:58 pm
by bg
RogerL wrote:The local hardware store has 3 X 3 3/16 for $2.29 ft or $1.89 ft per 20ft length. is that good?


I can get that size through my local supplier for $1.50/ft. I'd call around a bit. Hardware stores are almost always more expensive.

PostPosted: Wed Oct 19, 2005 9:55 pm
by RogerL
A gooseneck trailer?
I have an 2000 Toyota Tundra pick up.

PostPosted: Wed Oct 19, 2005 10:58 pm
by Nitetimes
On the way to Lowes I saw an older Nissan pickup (baby truck) with a gooseneck Scamp trailer behind it. The truck was just a 2X4 standard pickup, probably 4 cylinder. I was floored when I saw it, can't remember ever seeing a little truck with a ball in the bed. Just at a guess I'd sat the main trailer body was about 13' long plus the gooseneck section. Didn't even know they made those trailers in a gooseneck let alone one that size.
So I'd say a gooseneck might be an interesting option for you.