AnEv942
CA
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Joined: 10/10/2003
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Yes the T/L super hitch has chains but the really dont take any verticle load. They are mounted same horizontal plane so extension could/would bend a lot before much added tension.
Mark
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woodsxr
Calif
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Might as well add my bit of info.
When looking at hitch extensions, I found Reese made a 18" 6000lb extension.
I had thought about buying it but it would end up being shorter than I needed.
I ended up building a 24" extension close to the OPs design.
24"X2"x2" solid bar stock, 24" X 2 1/2" 3/16 wall square tube.
I drilled a few holes throught the tube in various locations and plug welded the tube to the bar stock.
I then sleeved the outside of the tube with 2 1/2" x 2 1/2" x 3/16 wall angle iron. plug welding the angle to the tube and welded the seams. The extension weighed in at 50lbs when complete.
This is being used with a 15,000lb Curt class V mount and 12000lb weight distribution hitch. This is to tow a 1200lb trailer with a 4400lb jeep loaded on it.
This setup has worked very well and I have no fear using it.
Good luck with your project
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Matthew_B
The boonies near Dallas, Oregon
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The trailer hitch design standard is SAE J684. The relevant tests to consider for weight distributing are:
6.7% of the trailer weight plus 2070 lbs downward and at the same time pulling 15% of the trailer weight.
6.7% of the trailer weight plus 2070 lbs downward and at the same time being pushed by 15% of the trailer weight.
20% of the trailer weight to the left and right.
A moment equal to 7.7 times the tongue weight rating plus 1750 ft-lbs.
So for a 6,000 lb trailer, a hitch should be designed to survive
2472 lbs downward and at the same time pulling 900 lbs.
2472 lbs downward and at the same time being pushed by 900 lbs
1200 lbs to the left and right.
A moment of 6370 ft-lbs.
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Matthew_B
The boonies near Dallas, Oregon
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SoCalDesertRider wrote:Maybe the engineer who did the tongue weight capacity calculation for you using 2" tube could re-do the calculation using 2" solid bar. Then we would have a better idea of what the limits of your hitch design are. I think it was unclear in your first post that you were using 2" solid bar, rather than 2" tube.
EDIT: fixing the numbers.
A solid bar 2" bar is 1.8 times stronger than a 1/4 wall 2" tube.
A 2-1/2 tube is 2.2 times as strong as a 2" tube if both are 1/4 wall.
* This post was
edited 08/01/11 02:23pm by Matthew_B *
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Matthew_B
The boonies near Dallas, Oregon
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ticki2 wrote:Question on the chains . The working load on 5/16 30 grade is 1900#. Since that is the working load and not the breaking load I would think that it already has the 2x safety factor built in. I could also easily go to 1/2" chain and turnbuckles if that is the weak point.
The problem is that the chains don't just see the tongue force, they see far more because of the geometry. Let's do a mental exercise here: try to pull up your tailgate with a rope right over it; that's an easy pull. Now try to pull it up from the front of the bed with a rope; it is much harder. That's because the pull isn't in line with the load. Your hitch is the same. The bar is being pushed in really hard and the chains have a lot of tension. That's where the other poster came up with the 4,000 lb number.
5/16 grade 30 has a 1,900 lb WLL, a 3,800 lb proof load and a 7,600 lb min part load.
I'd advise going to a higher rated chain. Perhaps a 3/8 or 7/16 grade 70 would be in order. Pay attention to the rating of ALL the hardware. You'll need to get parts from a rigging company not your corner hardware store to find parts that are load rated.
ticki2 wrote:Question on WD hitch. I don't understand what difference it makes if it is a 2" or 2-1/2" since it's relationship to the trailer would be the same and either is more than capable for the load.
2-1/2 is a bit marginal at 30+ inches with a heavy trailer. 2" without help is way beyond safe. I don't see major problems with your setup, other than I'd go with heavier chains. The one risk is that you'll find your setup far stiffer than a superhitch - only yours will fail first in it's current form.
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rabenfels
Colorado
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After readinmg all the expert testimony and advise I'm really hesitant of pulling anything with my hitch extension. Have the Class V Ford hitch (F350SD) and the Reese 48" extension to clear my 1131/1191. Using the chain that came with it and turnbuckles to stabilize side-to-side movement. That's all I did. Can I still pull 5,000# with tounge weight 500# or am I asking for trouble? Thanks
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Owyheedog
Weiser, Idaho
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Nope no supplemental braking module, never quite saw the need prior to this incident. And while overall and with hindsight having one would have been wise, I don't think it would have helped in this instance as there was no braking involved just a nasty bump on a Forest Service road. Even I can learn though. The Jeep now rides on a 16ft trailer WITH brakes.
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JoeChiOhki
Sauvie Island, OR
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Owyheedog wrote:Owyheedog wrote:
My experience with a very similar setup, minus the chains... I flat towed my Jeep Wrangler for several years thinking that with virtually zero tongue weight I would never have any problems. That was true until the day that I managed to hit just the right bump at the right time at the right angle resulting in bending the extension so bad that we had to unhook the Jeep and my wife had to drive it all the way home. And this wasn't with wimpy materials either, I tried to bend the extension back into shape using my shop press and couldn't even budge it. It now lives in my scrap iron pile and a Super Hitch/Super Truss lives in it's place.
This isn't a critique of what happened, I'm just figuring the physics in my head, but did you have any kind of supplemental braking module in your jeep (Blue ox, etc...)?
Nope no supplemental braking module, never quite saw the need prior to this incident. And while overall and with hindsight having one would have been wise, I don't think it would have helped in this instance as there was no braking involved just a nasty bump on a Forest Service road. Even I can learn though. The Jeep now rides on a 16ft trailer WITH brakes.
Thanks, that helped clarify how things happened in my mind, sometimes I get hung up on trying to reproduce how something occurred in my head and can get hung up easily.
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SoCalDesertRider
SanDiego, CA, USA
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Matthew_B wrote:SoCalDesertRider wrote:Maybe the engineer who did the tongue weight capacity calculation for you using 2" tube could re-do the calculation using 2" solid bar. Then we would have a better idea of what the limits of your hitch design are. I think it was unclear in your first post that you were using 2" solid bar, rather than 2" tube.
EDIT: fixing the numbers.
A solid bar 2" bar is 1.8 times stronger than a 1/4 wall 2" tube.
A 2-1/2 tube is 2.2 times as strong as a 2" tube if both are 1/4 wall. Thanks Matt.
How does my recommendation of using a 3" o.d. 1/4" wall tube for the extension bar stack up, by comparison of the other two, used with a 3" i.d 1/4" wall receiver tube on the hitch end, no chains helping, except to limit side to side movement?
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ticki2
NH
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Again I would like to thank everyone for taking the time to think about and respond to the topic. I pretty much felt that the chains needed work as many have mentioned . It's what was in the shop at the time and I wanted to get a feel for how the system was reacting.
I am heading out to Maine for a week or more for some work and some play . I hope it is more of the latter. I have copied the thread to date so I can reread portions of it off line. Internet where I'm going can be sketchy so I may not be able to respond often. I will also bring my old Steel Construction Manual and do some more homework. I'm affraid I have forgotten more than I remember. I can calculate the static loads but calculating the dynamic loads finds me lacking and falling back on experience . If anyone has a short course on dynamic loading calcs Im all ears.
Some have suggested a completly different hitch system and sometimes that makes sense , however most would not be compatable with my truck and what is already there thus the reason I am persueing this design.
I look foward to future responses when I return or have internet.
P.S. I will not be towing a trailer so everyone can relax and feel free to roam the highways.
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