Frame Question and Odd Wisconsin Use

[xccelagator]

I am planning to build a light duty offroad tear. Tear will be 10x5 due to we do not want too small. The design will be maybe Benroy, Grasshopper, or the new cub. The main box frame I decided to use 2x2x1/8 along with crossmembers very 2 feet. The tongue I will have to do my home work. Just wondering if anyone has any pointers on this?

The odd use is in Wisconsin is with permit is we can tandem tow trailers. I had a welder modified a 8 foot pop-up to tow a 12' zodiac-type boat with 25 hp OB attached. I know most go WHAT!! It is legal and safe depending on the person. I have done this and doing one trip 2000 miles round trip. If I do this with the TD I will run the main tube the entire lenght from hitch to hitch. Also wondering if anyone has built a frame this way too?

BTW, here are the Wisconsin's DOT permit regulations
http://www.dot.wisconsin.gov/business/carriers/forms/mv2743.pdf



Thanks,
Dan

PS, I am not crazy, just creative!!!

[madprinter]

For that setup I'd think you'd definately want brakes.
The way my luck runs, I'd loose the back trailer and not relise it until I was on up the road . Better get some good insurance too.

[Sonetpro]

[xccelagator]

Sweeeeeeeet!!!! Nice to see someone else beat me to it.

Dan

[brian_bp]

I'm not a fan of these multi-trailer rigs with conventional trailers, but if you're going to do it, Sonetpro's setup is one of the best I've seen:
- the tug is large (heavy, long wheelbase) compared to the trailers
- the front trailer has long coupler-to-axle length compared to the rear overhang (typical of teardrops, but not travel trailers)
- the rear trailer is very light

I would be very reluctant to set up one of these rigs, and certainly wouldn't do it without trailer brakes.

If I were to do it, the end-to-end central frame member would make some sense; on the other hand, if the tongue of the front trailer is designed for the total (of two trailers) weight, it would not need any other special design considerations, and if the rear trailer is so heavy that the force on the front trailer is a structural concern, maybe it's too heavy to tow.

[brian_bp]

The odd use is in Wisconsin is with permit is we can tandem tow trailers....

BTW, here are the Wisconsin's DOT permit regulations
http://www.dot.wisconsin.gov/business/carriers/forms/mv2743.pdf

Thanks for the informative link.

Just a snippet from that regulation to put this scheme in perspective...

Operation under this permit is not allowed during bad weather or hazardous road conditions.

Hmm... seems to be some sort of control concern there...

[Alphacarina]

The front trailer has long coupler-to-axle length compared to the rear overhang (typical of teardrops, but not travel trailers)

I think that's the 'secret' - The closer you can get the coupler to the axle, the better

Remember that when a tow vehicle turns right, it's hitch ball on the back starts out going to the left and the farther aft of the axle the hitch ball is, the more left it moves - This can induce sway . . . . especially in a double trailer configuration

Ideally, you would want the hitch ball on the tear as close to it's axle as possible . . . . if you had room under the trailer, welding a hitch ball to the axle itself would be perfect, though it would make coupleing/uncoupling very difficult - It would sure eliminate sway though

All the above is proven with 5th wheel trailers, which tow much better than conventional trailers simply because the coupling is just ahead of the tow vehicle's axle . . . . when the tow vehicle begins a right turn, the trailer doesn't start out by turning left

Don

[xccelagator]

The odd use is in Wisconsin is with permit is we can tandem tow trailers....

BTW, here are the Wisconsin's DOT permit regulations
http://www.dot.wisconsin.gov/business/carriers/forms/mv2743.pdf

Thanks for the informative link.

Just a snippet from that regulation to put this scheme in perspective...

Operation under this permit is not allowed during bad weather or hazardous road conditions.

Hmm... seems to be some sort of control concern there...

Yes, it is not something that you want to tow during bad weather nor winter months.

Dan

[xccelagator]

The front trailer has long coupler-to-axle length compared to the rear overhang (typical of teardrops, but not travel trailers)

I think that's the 'secret' - The closer you can get the coupler to the axle, the better

Don[/quote]

Hmmmmm......I like that ideal. I want less overhang in the back.

Here is a partial pic of what my welder did to our pop-up for the hitch.
Click Pic for more details



What I would like to do is run the main tube 2x2x1/4 wall front to back under the main frame and reinforce it with 45 degree angle tube gusset of same material. The main frame of the TD would be 2x2x1/8 tubing. The 18" receiver would have slide on to this and be welded in place. Or just weld the receiver under and box in with plate around the tongue tube.

As it stands now I am looking at inside dimensions of 5 ft x 9 feet long outside. The galley will be heavy, Cooler and battery on tongue. Ballpark axle will be 42" from the rear. Again these are ballpark figures and not exact!!

Currently I have been using Sketchup and designing from the inside out.

Dan

[brian_bp]

...What I would like to do is run the main tube 2x2x1/4 wall front to back under the main frame and reinforce it with 45 degree angle tube gusset of same material...

Wow, that's one heavy chunk of steel - about 36 kg or 79 lbs, and it's not even serving as part of the main frame. A 4"x4"x1/8" box would weigh the same, and be vastly stronger against bending forces. Is this much metal really needed?

Why not just put in the diagonal braces and skip the centre tube? It seems likely that the main frame rails can handle the stress of the hitch on the back, with the diagonals connecting them to the hitch location.

Or, if a a straight (or pole) type tongue is preferred to an A-frame, and this tube is being sized for the purpose of the tongue, either splice to a lighter tube a the second crossmember, or just pick a more efficient tube size for the whole length.

[xccelagator]

Maybe it is oversized material, Maybe not! I would rather default heavy than too light a wall thickest. Plus I would like this to offroad. Plus still in the planning stage too!

Dan

[brian_bp]

Maybe it is oversized material, Maybe not! I would rather default heavy than too light a wall thickest. Plus I would like this to offroad. Plus still in the planning stage too!

Dan

I'm not criticizing, and I realize that this is at an early stage. I'm just thinking that while thin tube walls are prone to welding problems and buckling, 1/4" is thicker than necessary. Box sections are more efficient if the same amount of material is used to make a bigger box with thinner walls. When the same weight is used as something like my example of 4"x4"x1/8", I think it becomes apparent that this is a lot of steel for the purpose.

[xccelagator]

Maybe it is oversized material, Maybe not! I would rather default heavy than too light a wall thickest. Plus I would like this to offroad. Plus still in the planning stage too!

Dan

I'm not criticizing, and I realize that this is at an early stage. I'm just thinking that while thin tube walls are prone to welding problems and buckling, 1/4" is thicker than necessary. Box sections are more efficient if the same amount of material is used to make a bigger box with thinner walls. When the same weight is used as something like my example of 4"x4"x1/8", I think it becomes apparent that this is a lot of steel for the purpose.

No I didn't take it as criticizing. I do tend to talk or type out loud.

I think you are right about the wall thickest would be too large and adding unnecessary weight. I have been playing with Google's Sketchup and sizing things up. I think I think I will get a frame design drawn up and post it up here in the coming week.

Dan

[brian_bp]

...I have been playing with Google's Sketchup and sizing things up. I think I will get a frame design drawn up and post it up here in the coming week.

Dan

Looking forward to it!

[Dan in Rhinelander]

I am planning to build a light duty offroad tear. Tear will be 10x5 due to we do not want too small. The design will be maybe Benroy, Grasshopper, or the new cub. The main box frame I decided to use 2x2x1/8 along with crossmembers very 2 feet. The tongue I will have to do my home work. Just wondering if anyone has any pointers on this?

The odd use is in Wisconsin is with permit is we can tandem tow trailers. I had a welder modified a 8 foot pop-up to tow a 12' zodiac-type boat with 25 hp OB attached. I know most go WHAT!! It is legal and safe depending on the person. I have done this and doing one trip 2000 miles round trip. If I do this with the TD I will run the main tube the entire lenght from hitch to hitch. Also wondering if anyone has built a frame this way too?

BTW, here are the Wisconsin's DOT permit regulations
http://www.dot.wisconsin.gov/business/carriers/forms/mv2743.pdf



Thanks,
Dan

PS, I am not crazy, just creative!!!

I have had this permit, and towed tandem here in the northwoods and had no problem with the setup. One word of caution about the brake setup, Brake-away is ok and highly recommended, but electric brake application can be tricky. Getting the brakes adjusted correctly to apply without causing the lead trailer to brake more aggressively than the rear can be a problem.

Good luck no matter which way you chose.


We gave up the tandem tow because of the cost of the permit being higher than the frequency of the necessity. A good roof rack for the vehicle to put the boat, canoe, or kayak was a much more cost effective long term solution for us.