Extending Trailer Frame to include tongue box

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Extending Trailer Frame to include tongue box

Postby troubleScottie » Fri Nov 03, 2017 12:24 pm

I am looking for advice on teardrop trailer design and how to incorporate a tongue box.

In looking at most designs, if there is a tongue box, the tongue box sits on the trailer's tongue ie the triangluar cross members of the trailer. I understand some of this is from adding the tongue box late in the build process or limitations in the trailer length.

But what if you know in advance that you want a tongue box AND you are creating a custom trailer.

There is at least one design that has the tongue box integrated with the cabin.

Would you want the box to fit on the main part of the frame? (resolving flexing issue of the tongue relative to the main frame AND load on the tongue ).

Would you want the box to be integrated with the main cabin -- part of the floor and side walls into the front wall of the cabin ? One reason might be to eliminate any holes for bring wires into and out of the tongue box.

What does this do for the 60/40 rule? Is the tongue box part of length of the cabin?

My current thoughts for the tongue box are to hold one or more batteries, battery chargers, connection to towing vehicle, and solar panel charger; solar panel storage, maybe extension cords/hoses/etc. It most likely will not be the width of the cabin (5')

Still not sure where the main electrical distribution will be.

In the front has advantage of
lots of surface area (in my current design)
easy access ( not under cabinets or really low)
deep area -- 9-12" depending on curvature
short run from battery
long AC runs not a problem: a push on number of long wires whether in front or back; AC really does not care.
The front has the disadvantage of
long runs for several DC appliances
possibly more wires
lose some storage space -- but most likely could increase the rear storage.

The rear has advantage of
more traditional
shorter DC runs to most big appliances eg frig, water pump
The rear has the disadvantage of
longer run to the battery(s)
less layout area eg cabinets, etc in the way
possible issue with water

Looking for suggestions.
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Re: Extending Trailer Frame to include tongue box

Postby halfdome, Danny » Fri Nov 03, 2017 2:18 pm

I'm not sure where you are in your build but if you haven't made the chassis yet it would be a good idea to make allowances for a separate tongue box.
I suggest to forget about putting more than one battery in the tongue box, too much weight.
My first build I put a full sized 12 volt battery in my over built tongue box and the tongue weight was way too heavy.

Since then I use battery trays mounted rear of the axle, one on each side.
I make trap doors/hatches from the cabin floor for easy access to the batteries.
My tongue box is approximately 11" deep x 25" at the highest point and 48" wide on a 5' wide teardrop.
It is a separate entity and butts up to the front of the teardrop.
Edit: My electrical center is behind the two small doors in the photo above.
Easy to build and access (right above the batteries) & keeps me out of the chiropractor's office :lol: .
I can store the small refillable propane bottles, 2 Coleman lanterns, side tables and essential items for teardropping.
:D Danny
Last edited by halfdome, Danny on Fri Nov 03, 2017 6:42 pm, edited 1 time in total.
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Re: Extending Trailer Frame to include tongue box

Postby tony.latham » Fri Nov 03, 2017 6:04 pm

If I ever build #4, I'll do the battery box, just like Danny's.



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Re: Extending Trailer Frame to include tongue box

Postby working on it » Fri Nov 03, 2017 6:11 pm

  • My trailer is unlike most others, since it has a single beam tongue, with a tongue box mounted on it and braced with two outriggers on the sides (forming the conventional triangular v-shape). And, it is on a slider, so it can be moved forward to unblock the spare tire behind it. I always intended for some sort of front mounted box on the tongue, and started with a small toolbox, until I was informed about a box ideal for my trailer, by another member here.
  • The front mounted spare behind the box was also intended, as the location easiest to access, and the centrally-mounted weight was needed to counterbalance the rear-weighted bias of my trailer, built more on a 55/45 ratio, with a generator and A/C unit adding too much weight in the galley area. It was just a question of if/when I could find the right box for the situation, so at first, my tongue was a little light. I made the tongue from a 6' long piece of 3"x 3" square tubing, .1875" thick, welded to three crossmembers, with 45" in front of the cabin wall, so there was no worry about tongue flex, with or without the box mounted there.
  • Before I realized exactly how heavy my trailers' rear area had become, I mounted my Optima Yellowtop battery there, with master cut-off switch, and running thru the bulkhead to a fusebox n the cabin; later I moved it forward to the small toolbox, then to the large aluminum tongue box after it was found. All my 110vac wiring, circuit breakers, etc remained in the galley. to run the cables from battery back to the rear, I used 4 gauge cable, and made a shielded slot in the rear of the tonguebox for them to exit from, wrapped in in flexible braided hose to prevent chafing, when the sliding box is moved.
  • I used slotted steel angle stock, doubled-up, as outrigger/stabilizers for the wooden platform I mounted the slider mechanism to. It was a plywood plate, with rollers under neath to contact the wooden platform (treated 2x4's), with linear bearings/boat seat sliders as the main piece. Moving forward 6" to uncover the locked spare tire, or slid back, and locked in place with a hasp, for travel.
  • My large tonguebox holds my extension cords, rope lighting, spare parts, park power adapter set, and nuts/bolts sufficient to repair my trailer, as well as the battery and trickle-charger for it. It weighs probably 200 lbs, loaded, and balances my trailer as I had intended all along. But, I keep adding gear, and I added a forward roof rack over it, to keep my trailer in a 10-15% tongue/total weight ratio.
  • My park power entry hole (for my simple extension cord feedline) is at the rear of my trailer, into the galley area, where I have easy access to the 110vac wiring and surge protector there. My 110vac circuit protection is provided by GFCI plug-ins, before any item gets energized. There's only one wire forward of my rear bulkhead, again to a circuit protector for the A/C unit, and a barely hidden extension cord goes forward again, to my large fan. I have LED lighting of both 110vac and 12vdc variety, and an inverter inside the cabin, in the 12vdc fusebox, just in case the parkpower fails. In a boondocks area, my 2500 watt onboard generator can power anything I use, and the extended-run tank I made, is good for about 11 hours.
  • As you can tell, my tonguebox plan was for weight balance as much as for storage, and my electrical plan was redundant power sources for lighting and A/C, and simple semi-exposed wiring for solving problems. My day-to-day needs are small, so ideal power placement, storage maximization, and weight balance problems are dealt with as best I can, after experience on the road. If you find a plan that others might've used before, with success, that might also work for you, then follow it. My struggle with modifications over the last few years is a caveat for others.
  • 114026114187114353 tonguebox slider, side supports,pulled out
  • 120568120569 generator & extended-run tank on sliders: out to run, in to store
2013 HHRv "squareback/squaredrop", semi-offroad, 4x8 TTT, 2065 lbs
  • *3500 lb Dexter EZ-Lube axle, w/brakes, 3000 lb. springs, & active-progressive bumpstops
  • *27x8.5-14LT all-terrain tires (x 3) *modified Weight Distribution system for single-beam tongue
  • *LED lighting, triple fans, Pioneer stereo *A/C & 110vac heat, Optima AGM, inverter & charger(s)
  • *extended-run, on-board, 2500w generator *Coleman dual-fuel stove & lantern, Ikea grill
  • *zinc/stainless steel front racks *96"L x 6"Dia. rooftop fishing rod/reel carrier
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Re: Extending Trailer Frame to include tongue box

Postby jondbar628 » Fri Nov 03, 2017 6:40 pm

My tongue box consists of a pvc battery box (for a group 27 deep-cycle battery), mounted on 3/4 ply treated with "the mix" and two coats of oil-based paint. The mount spans both arms of an HF trailer to add extra rigidity. I extended the tongue 18" with a centered 2"x1/4" box iron running back through the 3nd crossmember for trailerabilty & frame stability. Battery box center mount also bolts to this. I wanted the battery on the tongue because I didn't move the original wheel position. But I didn't want TOO much weight up front, so I intentionally didn't build a box big enough for other storage. Battery charger (another "weighty" component") sits at the front interior of the TD. Trying to keep the tongue weight at 10 - 12% of total. Haven't done the finishing touches, so I haven't checked the weights yet. To be done in the spring when I return to my northern build site......jd
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