How's my Trailer Design

[DoGood]

I'm planning on building a trailer similar to the one I have drawn here.
It will primarily be pulled behind my Jeep TJ (2k lbs towing capacity, though I need it to hold up to an entire load of firewood).

My questions are:
Am I using the correct size and thickness of steel for the different parts?

As shown in the picture, I plan to make the tongue length adjustable for hauling longer pieces of lumber or steel. I have the sizes shown in the drawing, will these slip in and out of each other efficiently and with enough strength? If not what would you recommend for material?

I am considering putting a drop down tailgate on the front and back of the trailer, but I am concerned that when loaded the sides may bow out. Could this be compensated for with gussets or should I not use a tailgate on the front of the trailer?

What thickness of steel should I skin the trailer with?


Untitled by patrickrohlich, on Flickr

Thanks

 

[jkm4874ford]

Nice design,
First define a whole load of firewood.

I think it is on the light side for a rick of firewood. But then again I am a fan of build it heavey and don't worry about it. I would start with what axel you plan on using. it is narrow for most standard axel setups. What floor will you use. You gain alot of stength in the floor system.

I would use 3/6" minimum wall thickness for the tube and use a rectanular shape like 2 x 3 in lieu of 2 x 2.

Extending the tounge is a good idea but you have no support for materials at the front. You are also extending the same basic length of the trailer, thus no length to push back into the reciever.

Good start look forward to seeing more.

 

[NUTTSGT]

Nice design,
First define a whole load of firewood.

I think it is on the light side for a rick of firewood. But then again I am a fan of build it heavey and don't worry about it. I would start with what axel you plan on using. it is narrow for most standard axel setups. What floor will you use. You gain alot of stength in the floor system.

I would use 3/6" minimum wall thickness for the tube and use a rectanular shape like 2 x 3 in lieu of 2 x 2.

Extending the tounge is a good idea but you have no support for materials at the front. You are also extending the same basic length of the trailer, thus no length to push back into the reciever.

Good start look forward to seeing more.

3/6" really ? That's like 1/2". I know you meant 3/16"

 

[larry_g]

Do you have a good reason for making the inside of the box 3' 10"? Most try for 4' plus to be able to handle sheet goods/plywood.

lg
no neat sig line

 

[ncfh]

There's a reason truck and trailer frames are made from open section, like U channel and angle iron, and not tube.

Tube corrodes from the inside out. By the time you see it, it's waaay too late.

Capping or "sealing" moisture out of tube actually makes it worse.

Look at any commercially made trailers, only the nonstructural items are made from tube, and when they do use tube structurally, it is always, always perforated to allow airflow somewhere. And it will still be the first member to corrode and fail.

 

[kbs2244]

http://www.tjtrailers.com/store/trailer-plans-blueprints.html

http://www.southwestwheel.com/store/c-211-trailer-plans.aspx

The best way to extend a tongue I have seen was what my uncle used when he converted his little utility trailer for carrying canoes.
It was just an 8 foot piece of 3 inch channel iron with a ball mounted abut 2 feet from one end and a hitch on the other end.
The ball would go up into the trailers hitch, a square “U” bolt would hold up the short end to the trailers tongue between the hitch and the trailer body and now the new hitch end was another 5 foot from the trailer.

He wasn't carrying any extra weight. He just need the length to clear the canoes hanging over the front of the box.

 

[KenS]

One of the more critical aspects of trailer design is placement of the axle. Do you have a print showing the location of your's?

 

[JeepsAreBuilt]

I also would go with 3/16" wall tubing.. and use all the same size for the frame... such as 2". And maybe 2.5" for the center support with the tongue.

 

[RonRock]

Building trailers is a good time. I have built several and will likely build more. But before you get too involved in the project you should check out the trailers at the local stores. I don't know if you have a Tractor Supply Store near you, but they have some hard to beat deals on small utility trailers. Maybe worth it to consider buying one of them and modifying it to your needs. You'd probably save money that way if you have to buy an axle and tires, steel and all the lights and etc.

Just something to consider.

 

[EdT]

Dry oak firewood weighs about 50# per cubic foot. LOTS more if its green or wet. A standard cord of wood is 128 cubic feet (4'x4'x8'). That means that a cord of dry oak firewood weighs about 6400 pounds. So even a small portion of a cord will put you over your tow weight limit. If you could make your trailer weigh, say, 200# you would be able to carry about 36 cubic feet or about .3 cords or if your trailer is 4'X8' you can stack it just a bit more than a foot high. And, that's if its bone dry.

 

[skiingman]

There's a reason truck and trailer frames are made from open section, like U channel and angle iron, and not tube.

Truck frames are made from open section because you can't stamp a closed section. Current truck frames are trending towards closed sections that are more complicated to manufacture but superior performing.

Trailer frames are built from whatever provides the required stiffness for the minimum number of dollars, which is often channel. I wouldn't think it wise to read much into their crappy corrosion performance. I see lots of trailers that are so poorly made they didn't make it to Home Depot without rusting/bending/losing lights/etc.

 

[FireMe]

2x2 will not fit inside 2.25 x 2.25 x 1/8, you will need some slop. You can buy specially made "receiver tube" from a steel supplier, or just use 2.5 x 2.5 x 3/16 wall which is much cheaper.

The extending tongue will not live long at 1/8 wall. Any slight bend will cause the tube to jam. I would use 3/16 or even 1/4 wall as there will be a lot of bending force from that long of a tongue.

Putting the receiver tube through the center of the frame is going to result in a huge amount of additional cutting and welding, and keeping everything aligned is going to be difficult without a jig or large welding table. I would just hang it on the bottom of the crossmembers.

As stated above, you are going to be able to fit about 2,500lbs of fire wood in there. I would definitely use at least a 3,500 lb axle, and would highly recommend a 5,200 lb axle as it uses 12" brakes, which your TJ is desperately going to need when the trailer is loaded.

As for sheet metal, I would probably use 11 gauge on the floor to prevent denting from the firewood, and maybe 14 gauge for the sides so long as you are going to build some type of rail at the top.


Jay

 

[slopecarver]

I would be worried about the sides splaying apart when you fill it with firewood, make the floor beams taller and the side beams wider to resist any bending load the firewood would put on the walls. I'm in the overbuild and don't worry about it category too.
Also: Brakes

 

[DoGood]

Thanks for all the great reply's. I will have to make some changes to my design and post again before I start the build.

To clarify how much I will be hauling, the goal is to carry less than 2,000 lbs if I take it on the road since that is the towing capacity of my vehicles. But, if I'm using it on the property I would plan to fill it all the way up. My Jeep has no problem pulling way more than 2k lbs, of course stoping it at road speeds would be another thing.

I plan to use an axle I already have from an older trailer. If I only have the axle, is there a way to know or figure out the weight rating on it? The bolt pattern is 5 on 4.5, same as my Jeep. I plan on using the same or similar tires, which are 33x10.5.

I have looked at modifying a pre made trailer but they don't seem to fit my goals. To compare a price, I first need a design so that I can price it out and make a real comparison.

 

[omr]

There's a reason truck and trailer frames are made from open section, like U channel and angle iron, and not tube.

Tube corrodes from the inside out. By the time you see it, it's waaay too late.

Capping or "sealing" moisture out of tube actually makes it worse.

Look at any commercially made trailers, only the nonstructural items are made from tube, and when they do use tube structurally, it is always, always perforated to allow airflow somewhere. And it will still be the first member to corrode and fail.

My jet ski trailers main beam is tube steel and the axle is tube steal.

 

[Steevo]

Slopecarver was the first to mention my first concern.

Towing a trailer full of firewood with a Jeep TJ will far exceed your braking capacity. The 2000# limit isn't about what it will pull, it is about what it can stop, and not ending up with a trailer that pushes the vehicle when braking on turns.
At approx. 4' x 6', loaded 3' high, you'd be carrying about 3600# in firewood, plus the trailer weight.
As Slopecarver said, BRAKES.

 

[ishiboo]

The extending tongue will not live long at 1/8 wall. Any slight bend will cause the tube to jam. I would use 3/16 or even 1/4 wall as there will be a lot of bending force from that long of a tongue.

Putting the receiver tube through the center of the frame is going to result in a huge amount of additional cutting and welding, and keeping everything aligned is going to be difficult without a jig or large welding table. I would just hang it on the bottom of the crossmembers.

Both good ideas.

Using a continuous "A" frame and receiver tube will be a lot easier and stronger (in practice) than cutting and splicing it into the overall trailer frame. This is why dump trailers/etc. always tie in this way... the hitch portion is welded to the trailer frame from below.

You can see the detail here... they are also gusseted which is probably overkill:

This usually makes it easier to get the right dimensions with the axles/tires, bed height, etc.

 

[Spareparts]

Trailer Brakes----Trailer Brakes, if you havent already upgraded your brakes you at the limits of your brakes now with the 33's. Upgrade the brakes or with a 2,000lb load you will be in the next county before you get stopped. Also when you are loaded keep it in 4 wheel drive, with the short wheel base it will try to swap ends under heavy braking, puts **** up in your neck when that happens.

 

[adam728]

Brakes is right!

I had a TJ for about 6 years, 33 x 10.50's and towed a small (5x8) enclosed with it.

The trailer with 1 bike, tool box, etc, weighed in around 1200 lbs. Stopping it was always, well, interesting. It wasn't a braking power thing, it was a short wheelbase and huge weight transfer thing, not to mention the TJ's EXTREMELY front biased brake proportioning. Upgraded everything, it just made it easier to lock the front wheels. I really should have added trailer brakes, but instead sold off the Jeep. 3/4 ton Chevy doesn't even know that little 5x8 is back there.


As to the trailer design, I'll go with the others, the tongue isn't going to work, and you'll want something stouter than 2x2 x 1/8 for the main frame. I'd go with a taller cross section for strength, but leave wall thickness the same. Going 2x3 or 2x4 with 1/8 wall will make a HUGE strength difference. If you look at most pickup frames they are generally only 0.090-0.120 thick, they use cross section to add strength and stiffness.

 

[EdT]

Further to the 2000# weight limit. Certainly the capacity of the braking system is critical and you can get trailer brakes to help address that issue. Another important concern is that the ordinary 2000# "bumper hitches" that I have seen are fastened to the bumper which is, in turn, fastened to the frame. Part of the weight limitation is the strength of the bumper and it's mounts. If you look at upgraded hitches, they seem to be much more robust and firmly fastened to the frame. I think this might become important if you are hauling a full trailer around the yard with a lot more twisting and wrenching on the hitch than you would usually find on the highway.

 

[Wdfp]

Your extendable tongue is going to cause you some problems and probably fail. with thicker metal it will take longer but the results will be the same depending on how you lock it down when extended. How were you going to do that? You cannot put a pin or bolt thru it, that would weaken it too much and it must be tight! You also need a fair amount of tongue left under the trailer, probably back as far as the deck anyway. You will want to clamp it there at the front of the deck and also 6" or a foot behind where it protrudes from the trailer tongue so it wont be trying to flex in one little place, that would be like welding all the way around it solid and that would be where it will break, But if you spread the flex in the tongue over a foot or so it will last with square tubing, but I wouldn't go more than 4 feet overall on the extension, you will want around 200 lbs or so weight on the ball so it will pull decent and not walk all over the place. I also think you should go with 2"x3" x3/16 minimum for the whole tongue assembly with the tall side vertical if you use tubing. 4" channel would be better for the v in front but you are at the absolute minimum for strength with 3/16 wall tubing, avoid large dips and bumps loaded..

 

[GarageEnvy]

I had an old boat with an extendable tongue. The tongue was round and heavy wall (probably about 3/8"). On a muddy launch it was great but in reality binding was a big problem. It always involved blocking the wheels. Empty, your trailer may be a different scenario but I agree it's probably more trouble than it's worth.

I also made a beautiful black powdercoated trailer with a 5'x10' aluminum diamond plate deck for hauling dirt bikes behind my jeep cherokee. I made it out of very light metal and regretted it. You always seem to use a trailer for more than you intended. The jeep was replaced with a Tahoe and I wanted a heavier duty trailer. Build it bigger and heavier than you think you need and put tie down rings as often as possible. You'll thank yourself some day.

 

[Hipjake2]

This was one of my projects. A buddy had a pretty old dilapidated snowmobile trailer. Wood was rotten, and I hated the fact, the tires were completely under the trailer. (I wish I had taken some pics of the rebuild) I stripped it down and made reinforcements where needed. I actually cut the sides off that hung over the tires. I was able to get some nice aluminum plate from where I worked. Having access to a CNC waterjet to cut out the panels I needed, the tailgate and the light covers. I used a roller to make my own wheel wells. I even formed up my own u-channels for the wood sides I added. Although i put them on the inside, I lose a little width but I liked the cleaner look on the outside. A fresh sheet of plywood and my signature foot to hold it in place when parked. It's not for everyone, but it has been perfect for hauling a rider mower or a snowblower when I needed. I still want to add a lock box to the front for straps, bungies, tarps, etc...

(First pic is just an example of what I started with)

 

[hunter1151]

There's a reason truck and trailer frames are made from open section, like U channel and angle iron, and not tube.

Tube corrodes from the inside out. By the time you see it, it's waaay too late.

Capping or "sealing" moisture out of tube actually makes it worse.

Look at any commercially made trailers, only the nonstructural items are made from tube, and when they do use tube structurally, it is always, always perforated to allow airflow somewhere. And it will still be the first member to corrode and fail.

Most boat trailers are made from tube..........???

 

[Rezarf]

Truck frames are made from open section because you can't stamp a closed section. Current truck frames are trending towards closed sections that are more complicated to manufacture but superior performing.

Trailer frames are built from whatever provides the required stiffness for the minimum number of dollars, which is often channel. I wouldn't think it wise to read much into their crappy corrosion performance. I see lots of trailers that are so poorly made they didn't make it to Home Depot without rusting/bending/losing lights/etc.

Agreed, channel is only cheaper, nothing more. Tube is way stronger in the same wall thickness. Corrosion is best combatted with coatings.

2x2 will not fit inside 2.25 x 2.25 x 1/8, you will need some slop. You can buy specially made "receiver tube" from a steel supplier, or just use 2.5 x 2.5 x 3/16 wall which is much cheaper.

The extending tongue will not live long at 1/8 wall. Any slight bend will cause the tube to jam. I would use 3/16 or even 1/4 wall as there will be a lot of bending force from that long of a tongue.

Putting the receiver tube through the center of the frame is going to result in a huge amount of additional cutting and welding, and keeping everything aligned is going to be difficult without a jig or large welding table. I would just hang it on the bottom of the crossmembers.

As stated above, you are going to be able to fit about 2,500lbs of fire wood in there. I would definitely use at least a 3,500 lb axle, and would highly recommend a 5,200 lb axle as it uses 12" brakes, which your TJ is desperately going to need when the trailer is loaded.

As for sheet metal, I would probably use 11 gauge on the floor to prevent denting from the firewood, and maybe 14 gauge for the sides so long as you are going to build some type of rail at the top.


Jay

I agree wit,h most of what jay says here but often tube will fit in another depending on the seam inside the tube. You'll have to check it out at the steel yard. I would bump up to 1/4" wall on the extension pieces. I built a trailer with an adjustable tongue and this has worked very well for countless off road miles.

Your extendable tongue is going to cause you some problems and probably fail. with thicker metal it will take longer but the results will be the same depending on how you lock it down when extended. How were you going to do that? You cannot put a pin or bolt thru it, that would weaken it too much and it must be tight!

I disagree, this simply isn't true. If well designed and built it will be just as strong if not stronger than a solid tube due to the doubled up wall thickness. My slip joint tongue is 1/2" thick that the joint for over 2' overlap.

Here's what I built 5 years ago... It still working awesome.

 

[DoGood]

^Thats basically what I'm wanting to build, Thanks for sharing the pics.

My trailer is still in design, but I hope to get started on it... when I finish everything else I'm working on.

 

[roberts56]

@Rezarf,

WOW, that's an awesome great looking utility trailer you got there man, just love it and very inspiring, my imagination suddenly got tickled.

Thanks for sharing some pics.