Trailer frames and ratings

[KMB]

Doing more trailer research (for firewood). This might be a question for the fellas that have built trailers and know about iron specs. and so on. I’ve been looking at the specs. of different trailer manufacturers, in particular the 7K rated utility trailers (tandem axle, 77” or 83” wide, 16’ long minimum, and with 3500lb. axles). Regarding the main trailer frame materials, so far I’ve seen 3” x 2” x 3/16” angle, 3” x 3” x 3/16” angle, 3” x 3” x ¼” angle, and 4” x 3” x ¼” angle. Cross members have been 3” x 2” x 3/16” angle and one had 3” x 3” x 3/16” angle. Also some have A-frame channel tongues and others have channel wrap tongues. My question mainly is about the different angle iron sizes for the frames. Would the 3” x 2” x 3/16” angle frame need more cross members on center than the ‘larger’ angle iron frames I’ve mentioned to be up to the 7K rating? Is the 4” x 3” x ¼” angle frame trailer ‘over built’ for a 7K rating?

Some of the trailer manufacturers that I’ve been looking at start at a 7K rating for their utility tandem axle trailers, except for Big Tex where I think that a 4K rated utility tandem trailer is where they start. Big Tex’s 5K trailer has a 3” x 2” x 3/16” angle frame, 3” x 2” x 3/16” angle cross members, and an A-frame channel tongue. The 6K version has a 4” x 3” x ¼” angle frame, 3” x 2” x 3/16” angle cross members, and an A-frame channel tongue. The 7K version has a 4” x 3” x ¼” angle frame, 3” x 2” x 3/16” angle cross members, and a channel fold back (wrap) tongue. I should add that all 3 of these trailers have 2-3500lb. axles. One other company has a 7K rated trailer built like Big Tex’s 5K trailer. A few other companies have their 7K rated trailer built the same way as Big Tex’s 5K trailer except with a channel wrap tongue. It seems like Big Tex ‘over builds’ their trailers…correct? I do know they are higher priced as well. Can anybody shed some light on this topic?

Kevin

 

[daddy]

Kevin, my general take on manufactured trailers is that they are built to a price point, and that they are built to the minimum standards possible.
I would say the big tex is not overbuilt, but rather the others are underbuilt.
I'm not a real big fan of angle for frames. I like channel.

This is a mid construction pic of one I built. It has 3500# axles, 5" channel frame and what I call "jr. I beams" for crossmembers.(4" tall).

 

[KMB]

Kevin, my general take on manufactured trailers is that they are built to a price point, and that they are built to the minimum standards possible.
I would say the big tex is not overbuilt, but rather the others are underbuilt.
I'm not a real big fan of angle for frames. I like channel.

This is a mid construction pic of one I built. It has 3500# axles, 5" channel frame and what I call "jr. I beams" for crossmembers.(4" tall).

Thanks for the reply. I guess there's not many that notices these details. I try to thoroughly research any purchase that to me is lots of money. I probably research to much sometimes...oh well.

I think I would agree with your statement about other manufacturers being underbuilt or built to the bare legal minimum. Like you also mentioned, the pricing shows this also. I'm still deciding about getting a single axle trailer for now (I have reasons) and adding a tandem axle trailer later (yep, I have more reasons) OR just getting a tandem alone. Either way, I'll try and find the balance between price and trailer build quality.

Good on ya for having the skills and tools/equipment to build a trailer to your specs.

Kevin

 

[Captain Crunch]

Many typical utility trailers made with angle frames have a top rail in addition to the main rail. Calculating the strength with the top rail is much more complicated than if there only a main rail.
To keep things simple, you can compare the moment of inertia of the main frame rails for different sizes. Here links for angle with unequal leg length and equal leg length. Look at the Ix column.

http://www.engineeringtoolbox.com/steel-angles-unequal-legs-d_1323.html

http://www.engineeringtoolbox.com/steel-angles-d_1322.html

Again, since there IS a top rail, things are much more complicated.

I agree that the c channel is a far better shape, far stronger and stiffer for the same weight, or much lighter for the same strength. There are tables online, mostly for heavy C's not typcial of trailers. The calculation is not hard. I can post the equation later if you are really interested.

Steve

 

[KMB]

Many typical utility trailers made with angle frames have a top rail in addition to the main rail. Calculating the strength with the top rail is much more complicated than if there only a main rail.
To keep things simple, you can compare the moment of inertia of the main frame rails for different sizes. Here links for angle with unequal leg length and equal leg length. Look at the Ix column.

http://www.engineeringtoolbox.com/steel-angles-unequal-legs-d_1323.html

http://www.engineeringtoolbox.com/steel-angles-d_1322.html

Again, since there IS a top rail, things are much more complicated.

I agree that the c channel is a far better shape, far stronger and stiffer for the same weight, or much lighter for the same strength. There are tables online, mostly for heavy C's not typcial of trailers. The calculation is not hard. I can post the equation later if you are really interested.

Steve

Thanks for your input Steve. For what I have seen available manufactured 'locally', I will be trying for one of the 4" x 3" angle frame utility trailers. It looks like to get into a manufactured C channel frame trailer, you have to go to a 12K rated trailer and that would be to much trailer for my half ton (and my wallet).

Edit: I stand corrected about what size trailer I have seen online that is built with a C channel frame. I saw a 9995 lb rated trailer that has a 5" C channel frame.

Kevin

 

[kstill361]

Thanks for your input Steve. For what I have seen available manufactured 'locally', I will be trying for one of the 4" x 3" angle frame utility trailers. It looks like to get into a manufactured C channel frame trailer, you have to go to a 12K rated trailer and that would be to much trailer for my half ton (and my wallet).

Edit: I stand corrected about what size trailer I have seen online that is built with a C channel frame. I saw a 9995 lb rated trailer that has a 5" C channel frame.

Kevin

Are you going to build one?

My 2007 20' car trailer has 5" channel main frame with 4" channel wrap tounge. 2 3500lb axles. Its not a utility trailer but has stake pockets. I just put a fresh coat of stain on before winter this year. I got it in Sikeston MO , from Jerry James Trailers for $1835. The options I got with it include 2 brake axles, new wheels and tires, treated deck , extra wide, and breakaway kit

 

[KMB]

Are you going to build one?

My 2007 20' car trailer has 5" channel main frame with 4" channel wrap tounge. 2 3500lb axles. Its not a utility trailer but has stake pockets. I just put a fresh coat of stain on before winter this year. I got it in Sikeston MO , from Jerry James Trailers for $1835. The options I got with it include 2 brake axles, new wheels and tires, treated deck , extra wide, and breakaway kit.

Nice trailer. What do you pull it with?

No, I'm not going to build one. I use a borrowed 7K rated car hauler (Big Tex 70CH) that I've built removable wood sides for, but I would like my own trailer. Usually the trailer is readily available, but there have been times when I needed the trailer and it was not available for a few days...such as it is when you don't own something. I had thought about getting a similar car hauler, but without the dovetail. My approach/driveway has just enough of a slope so that the dovetail will sometimes rub momentarily. A car hauler allows for better, sturdier removable sideboards than a utility trailer, but thicker plywood cut in half to make 2' x 8' side boards would work for me. With the 24" sideboards in the stake pockets on the car hauler I use, it's about 27" to the top of the boards from the trailer floor. I can fit a thrown-in full cord with no problem and the trailer carries it very well. The weak link is my half ton...but I take it easy going down the road. The trailer has 1 brake axle, and my truck (1997 F150 SC 4x4, rated to pull 6600 lbs. with the 4.6L V8 and 3.55 gears that it has) has a tranny cooler, Timbren springs and heavier duty shocks. Those things help...but at the end of the day it's still a half ton...and it'll have to do for a while. I'll add that I like the use of a tail/ramp gate on a utility trailer.

I priced this trailer today with some options to see what I to save for. It is 83" x 16', and the options are the 4" x 3" x 1/4" angle frame, 48" tail gate with 2 extra supports and a spare tire mount. $1887 out the door. There are more frame options (5" x 3" x 1/4" angle, and 5" and 6" C channel), but for my truck, this would be enough trailer. If/when I could get into a 3/4 ton or 1 ton later, I'd sell the trailer and upgrade to a 10K or 12K trailer which would have the 5" angle or C channel frame. The only other option I would be undecided on is brakes on the second axle. Knowing how the loaded (1 cord) trailer I use stops with one brake axle, which is okay, I think I'd like extra braking...especially in an emergency. With a second brake axle, it would probably put the trailer over the $2000 mark. We'll see.

Kevin

 

[Haywire Haywood]

I've been trying to look for a trailer recently too, for a march purchase. I want a 6x12 tandem with both axles braked. The only guy I've talked to doesn't stock tandems smaller than 7x14. I want a compact 7k trailer. I have essentially the same truck as Kevin. 04 F150 4x4, 4.6L, 3k lb "Supersprings" helpers and a brake controller. Kevin's has an advantage over mine in that it is geared lower. IIRC mine has 3.31 gearing.

I want one build adequately for the purpose but not overbuilt so that I waste towing capacity pulling steel down the road.

Ian

 

[kstill361]

I still got the 1/2 ton 2003 F-150 4x4 with 5.4L .
I remember seeing a picture of that trailer you borrow. I would like to upgrade to a 3/4 ton truck myself someday.

 

[KMB]

I've been trying to look for a trailer recently too, for a march purchase. I want a 6x12 tandem with both axles braked. The only guy I've talked to doesn't stock tandems smaller than 7x14. I want a compact 7k trailer. I have essentially the same truck as Kevin. 04 F150 4x4, 4.6L, 3k lb "Supersprings" helpers and a brake controller. Kevin's has an advantage over mine in that it is geared lower. IIRC mine has 3.31 gearing.

I want one build adequately for the purpose but not overbuilt so that I waste towing capacity pulling steel down the road.

Ian

Very good point. That's why, for my truck and the weight I'll be putting on the trailer, I think the 4" x 3" x 1/4" angle frame would be plenty good enough for me. A 3" x 3" x 1/4" angle frame might work, but most manufacturers seem to go from the 3" x 2" x 3/16" angle to the 4" angle frame with nothing in between. I myself would feel better with the 4" angle frame for a 7K rated utility trailer.

And...LOL...I found a trailer manufacturer online that builds a 7K rated trailer with a C channel (4") frame. I'm having to eat my words about that I've only seen 12K rated and higher trailers with C channel frames. For curiosity, I'm going to try and get a quote from them (PJ Trailers).

Kevin

 

[KMB]

I still got the 1/2 ton 2003 F-150 4x4 with 5.4L .
I remember seeing a picture of that trailer you borrow. I would like to upgrade to a 3/4 ton truck myself someday.

What gears does your truck have?

This might be the picture you saw of the borrowed trailer and my truck:

Kevin

 

[Mntn Man]

Why not find a used one? I got super lucky and found this off of Craigslist for $1500. It is a 2005 model 82 inches by 18+2 foot deck and 12,000 GVW. It has box tube cross members on 24 inch centers. This is at least the 3rd time posting this pic so, sorry. My truck is a Chevy 1/2 ton with 3.42 gears (perfect rpms at 55-60 mph out of overdrive) and the 5.3 engine. It pulled this just fine but it wasn't like I was trying to set any land-speed records. I have a 30 foot camper that I pull and can get 10 miles a gallon if the the wind isn't blowing. I can even put a trailer with 2 quads behind it, though I prefer not to because I am over length and it starts to pull harder than I like. You may be surprised what you can do with your Ford. It's not like you are going to be doing it day in, day out.

My cousin has an 18 foot 7000# rated trailer that he pulls with a cummins (chipped) powered Dodge. He wants to trade trailers.:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:

 

[Nick359]

I second the look for a used trailer. I found this one for $800 a few days ago on Craigslist. It needs new wood, which I bought today for $201 including the sides. I wish I would have seen Mntn mans' pic before I bought the wood. I think I like the 2x10 or 2x12s better than the three 2x4s with a gap, that I thought of on the way to Lowes.

Mine is a tilt deck 7k car hauler. I will use it to haul a truck to the drag strip and mud pits, a tractor to odd jobs, and firewood.

The last pic is my warn 9k winch that I run off of a deep cycle battery. I use it on several vehicles, so I don't want to hardwire it. I got all the logs on the trailer before the battery died. I will be getting a new cable, and making a better mount for the winch on the trailer.

 

[Dan_IN_MN]

Someone mention trailers?

I just acquired a tandem (both brake) axle frame that used to have a camper on it. I don't even know the length of this thing! I'll probably shorten it a bit. It needs a deck and probably some strenghting. It's from an older camper so I'm betting the frame is a bit thicker than the newer ones. The coupler takes 2 1/4 ball (that is if I can remember correctly. I think I'll change it to 2". The good thing is I run a CNC plasma cutter for a metal fab shop in town. He also builds trailers!

Currently it's under ~1-2 feet of snow.

I like the idea of removable sides.

 

[Haywire Haywood]

Very good point. That's why, for my truck and the weight I'll be putting on the trailer, I think the 4" x 3" x 1/4" angle frame would be plenty good enough for me. A 3" x 3" x 1/4" angle frame might work, but most manufacturers seem to go from the 3" x 2" x 3/16" angle to the 4" angle frame with nothing in between. I myself would feel better with the 4" angle frame for a 7K rated utility trailer.

Something I thought about to beef up an angle tongue would be to weld a piece of 1.5" x 1/4" wall round tube into the inside of the angle. I thought that would add strength and serve as a wire conduit too. Sound idea?

Ian

 

[SkyP]

The options I got with it include 2 brake axles, new wheels and tires, treated deck , extra wide, and breakaway kit

New wheels and tires were an option?
Actually there is a federal safety standard that makes it illegal to sell a NEW trailer with USED tires. A local dealer near me got in trouble for this, but I do see it done from time to time by the clueless. A purchaser can have the dealer install used tires if the purchaser owns them, the dealer cannot supply and sell used tires on a new trailer.

http://www.longhorntrailers.com/pdf/Installation-of-Used-Tires.pdf


I have a car trailer I bought in a pinch a few years ago, it didn't have the federally required clearance lights for an over 80" wide trailer, I added them later. It also had a 5000lb rated coupler on a 7000lb rated trailer. When I noticed this later I called the manufacturer and was told, aaah it will be ok its strong enough. I asked them how they'd convince a jury of that if it ever failed and hurt someone. Bottom line they sent a welder to town who cut off all the underrated couplers and put on new higher rated ones.
Point being there is a lot of shoddy stuff in the trailer biz, so caveat emptor.

I don't like box tube trailers, my dump trailer is that way, noticed one day rusty water leaking out of a porous weld. I drilled small drain holes in both ends of every member to let them drain, it was amazing how much rain water was in some of the members. I suppose if all welds were perfect it wouldn't be an issue. Rust in the interior would take a toll eventually, especially where they use salt. I did later blow a FluidFilm mist through each box tube, hope it coated most of the inside to prevent future rust.

 

[KMB]

Something I thought about to beef up an angle tongue would be to weld a piece of 1.5" x 1/4" wall round tube into the inside of the angle. I thought that would add strength and serve as a wire conduit too. Sound idea?

Ian

Ian, sounds like a good idea. Conduit for the wire is always good on a trailer for protection from the elements.

Kevin

 

[KMB]

Why not find a used one? I got super lucky and found this off of Craigslist for $1500. It is a 2005 model 82 inches by 18+2 foot deck and 12,000 GVW. It has box tube cross members on 24 inch centers. This is at least the 3rd time posting this pic so, sorry. My truck is a Chevy 1/2 ton with 3.42 gears (perfect rpms at 55-60 mph out of overdrive) and the 5.3 engine. It pulled this just fine but it wasn't like I was trying to set any land-speed records. I have a 30 foot camper that I pull and can get 10 miles a gallon if the the wind isn't blowing. I can even put a trailer with 2 quads behind it, though I prefer not to because I am over length and it starts to pull harder than I like. You may be surprised what you can do with your Ford. It's not like you are going to be doing it day in, day out.

My cousin has an 18 foot 7000# rated trailer that he pulls with a cummins (chipped) powered Dodge. He wants to trade trailers.:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:

Nice trailer you have there. Any idea of how much wood is on there? What I mean is if you stacked it, what were the stack dimensions as to figuring how many full cords are on that trailer. Out of curiosity, what is the tow rating on your Chevy? Do you have any suspension upgrades/mods? I know I have a lot of questions, just interesting to see what other folks are doing with their trucks and trailers.

I agree that I don't haul firewood day in, day out. I know that a trucks specs might be less than what it can actually do and the manufacturer has to protect itself, but for me the specs are a basis for me to go by. Maybe I'm chicken or baby my truck to much, but I'm careful in how I use my truck. When I'm loading the trailer I check the Timbren springs to see how compressed they are. When I'm going down the road loaded (out of overdrive), I'm listening to what the truck is doing. For me and my truck, I feel that a full cord of green oak (about 5500 lbs) on a 1800 lb trailer (approx. weight of a 16' x 83" 7K rated trailer...from some of the specs I've seen) would be tops. It would be 700 lbs over what my truck is rated for. I know, I know...there I go with spec numbers again....

Kevin

 

[KMB]

Why not find a used one?

I second the look for a used trailer.

I wouldn't mind used at all...if I could find very close to what I want in a trailer. I've already mentioned what I would want in a trailer. I'm kinda picky on some things . I do look on CL, look over the local papers, and see what's for sale as I drive through the country side. I'm guessing that I'll have to eventually buy new. If I do find a used one it'll probably be 2 or more hours away one-way. There's not much used locally that I have seen. I'd hate to drive that far and see that a trailer is not what I want.

New wheels and tires were an option?
Actually there is a federal safety standard that makes it illegal to sell a NEW trailer with USED tires. A local dealer near me got in trouble for this, but I do see it done from time to time by the clueless. A purchaser can have the dealer install used tires if the purchaser owns them, the dealer cannot supply and sell used tires on a new trailer.

http://www.longhorntrailers.com/pdf/Installation-of-Used-Tires.pdf

Good info to pass on.

I have a car trailer I bought in a pinch a few years ago, it didn't have the federally required clearance lights for an over 80" wide trailer, I added them later. It also had a 5000lb rated coupler on a 7000lb rated trailer. When I noticed this later I called the manufacturer and was told, aaah it will be ok its strong enough. I asked them how they'd convince a jury of that if it ever failed and hurt someone. Bottom line they sent a welder to town who cut off all the underrated couplers and put on new higher rated ones.
Point being there is a lot of shoddy stuff in the trailer biz, so caveat emptor.

Good stuff to know. This is part of the reason why I like to know the detailed specs. on trailers. Sometimes the specs. might be hard to find out on a used trailer...but not always the case.

Kevin

 

[Mntn Man]

I don't know how much wood is on there. Hopefully, I'll get it unloaded this weekend, then I'll know. It is mostly stacked on the trailer (vertically) so it is tighter than just thrown in.It is ash that was cut down last year and the year before so it is much lighter than green oak would be. I was going to weigh it so I would have a baseline and I may get that done today.

I have plenty of room on both sides of the axles to adjust tongue weight and have to pay attention to that when I'm loading it. I also do a brake check before hitting the road, checking for function and adjustment. (very important)

My 2006 Chevy 1/2 ton extended cab 4x4 is rated at about 8,000 lbs depending on who you believe. The motor is the 5.3 liter aluminum block (310 hp) with slightly higher compression than the iron blocks. It also gives me 300 lbs. more payload. It has the off-road package so the springs are a little stiffer and higher than some. I also have added 6 ply tires and extendable camper mirrors. My camper is about 8000 lbs and it pulls like butter, most of the time I don't even use the sway control and load leveler unless it is windy. People are amazed when I show them my MPG figures from trips and it is 8-11mpg. I don't take off or stop very hard and usually keep it at 55-60 depending on wind and terrain. When I bought it, I was skeptical about the 3.42 gearing (wanted 3.73), but is seems to be just right. My all around mileage is about 12-15 mpg but that is mostly in town just to work and back. (3 miles there and 5 home because I have to go get the kids)

I baby my truck also. My last one I had for 14 years (18 years old when I got rid of it) and this one I bought new over 4 years ago and I just rolled it over to 46,000 miles. I dented the tailgate once with a piece of wood and it drove me nuts so I had to have it fixed. I don't allow my wife to put wood in it because she refuses to place it in there and just wants to throw it from wherever she is standing.

On the sideboards, I just used what I had laying around and realize that I will be adding to what is there. I just didn't want to be lifting the wood any higher than I had to.