Two Design questions...

[Rezarf <><]

Two questions here and I would love your opinions.



1. I have recently built a rear tire carrier that I love. However, as I look into hooking up a scratch built trailer my pintle hook will not open without hitting my rear tire carrier "bumper.

Do you think that spacing the pintle out with a steel block, or heavy wall tubing and then bolting up the pintel would be safe?I am thinking of 3x4" tubing with 1/4" wall with the sides boxed and bolted up to the crossmember and into the pintle, with seperate bolts.The cross member is barely 3/16" thick. Will the forces increase that much to not consider this as a viable, safe option?Billet steel is another option but hard to find in thick chunks.



2. Frame design. On the m101 can and m416 trailers the A-arm drawbars are both tied into the front shackle hanger mounts. Stregnth is increased in this design because the chasis can be tied into the leading edge of the trailer as well, just like the m416's. However, do you think the losses in strength would outweigh the gain in useable space of connecting the drawbars to the front corners of the trailer. By connecting the drawbars to the corners of the front edge of the trailer I can pick up nearly 1.5' of extra surface area to strap things down onto it. Strong welds are not the issue, either option will be properly TIG welded. What would you do and why?

Clear as mud? thanks for your opinions.

Rezarf <><

[big sky trapper]

If I understand you ??? about the pintle .... you are using one of the 4 bolt, bolt on style that would bolt into a slide in type reciver hitch, Or even one of the direct frame bolt on pintle's. ???

If so then I would say yes that is acceptable mounting option. 3x4 or 3x5 both x 1/4 would be plenty strong esp if your are only needing a 3-5 inch extension.
I would make your adapter block as wide as the mounting pad. and weld the bolts heads/nuts to the inside (watch your heat esp with the tig...) then box the sides as needed.

I ve run almost the same thing for many years of some of my rigs and never had a problem. That is assuming we are talking smaller offroad utillity type trailers ect you should be fine.

the trailer ??? Im not understanding quite what your describing so ill defer to some one else......

any one else???

[Rezarf <><]

Yep, that is what I am using for a pintle.

Small m416 style trailer.

Thanks for the tips.

[Rezarf <><]

Maybe this will stir up some discussion?...

Would this work?

[Rezarf <><]

Which would you run? The first or the second?...

The first one has better triangulation of the chasis, at the cost of a useable platform in front of the "box."

[PhulesAU]

I'd vote for #2. 1st that corner looks like a great place to get hung-up. 2nd as light as the trailer is going to be "I" wouldn't think there would be loss of needed frame strength.

[Grim Reaper]

Since you are scratch building the frame #2. You can notch the frame and pull it in without fully cutting it. Just have to do the math to make the notch at the correct angle to meet up

[DaveInDenver]

Heya Drew.

I have two thoughts for you. First is on the second, your trailer. I would say either way could be fine, but my first blush is the second one with gussets would work well.

Now, about that pintle spacer. I would not just space out the pintle with a 4" block and really long bolts. If that was only for the trailer, it would probably be fine, but a pintle (really any tow point) serves us as recovery points. Technically a tow point isn't really a proper recovery point. The most common one is a class III tow point, which is only rated to 5000 or 6000 lbs (I forget which). Anyway, even my little Hilux fully loaded easily blows way past 5300 lbs curb weight, which means in a dynamic recovery that actual force on the recovery point is much higher, easily twice that. We get by because most tow points are built beyond their minimum rating. So you are using 5-ton pintle or something? This rating assumes a surface mounting and you'll probably be using four grade 10.9 14mm bolts (or maybe grade 8 1/2"). By spacing the pintle 4" away from the surface, you have significantly changed the loading on the tow point and bolts, particularly in an off axis recovery.

So I think personally I would do it like a good wheel spacer. Bolt the plate to the rear frame member and then a second set of bolts to the spacer. I would use a solid piece of stock and counter bore four holes to mount to the frame and offset the four counter bored holes for the pintle lower or higher whichever works best. Just my $0.02.

[Sgt Grunt]

I extended mine like your drawing #1. The reason I did it that way was so I could jackknife the pull vehicle a little more than 90 degrees to the trailer, so I wanted to keep it narrow up front to avoid contact with my bumper and spare tire. I hope that makes sense... I was going to put a tool box up front, but decided to put the propane bottles instead.

[FourbangerYJ]

Which would you run? The first or the second?...

The first one has better triangulation of the chasis, at the cost of a useable platform in front of the "box."


#2 is what I have in mind for mine,when I get around to building it. I plan to add another cross brace between the pintel and your box. Then triagulate (sp) 2 more from the center of the box out to the edge of the new crossmember. |<| kinda like that. IF it makes sense?

#1 would work better if you put the drawbars under the box. That way you can use the area in front of the box for storage.

[Rezarf <><]

Thanks for the replies... still wrestling over this one. For the weight of this thing it may be overkill to mull on this too long, but I want to do this only once, and get it right at that.

Drew

[ntsqd]

As you increase the length of the spacer you give the trailer more leverage to tear the spacer off the frame. A proportionately larger bolt pattern for the spacer to frame join is highly recommended.

Trailer tongue design No.2 is specifically warned against in M. M. Smith's books (Vol. 1 (http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_14707_14707)and Vol. 2 (http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_12729_12729)) on designing & building trailers. I only have Vol. 2, so it must be in that one. The basic argument against has to do with the Bending Moment that exists at the point where the tongue joins the rest of the frame.

[Rezarf <><]

Thanks I appreciate the reply. My space will only be 3" off the crossmember... if I go that route.

Thanks!

Drew

[FEF]

As I found out, pulling a trailer on Black Bear, you will likely need to jack-knife.

If you plan to pull on some tough trails, I recommend designing it the tongue such that there's one piece of box iron (maybe 3x3, or 4x4) as the tongue, and it's only as long as 1/2 the width of the tow vehicle.

My small trailer is setup such that there's a 2" receiver in the trailer tongue. On the hiway, I have a 3' section with a ball hitch, and at the trail head, I take the section off, and put on the pintle ring. It pulls like a dream on the road, and I can see it well when backing, because it's longer.

The down side to my configuration is that I can't have a rotating pintle on the truck due to the 2" receiver, and it's a few extra minutes at the trail head. The plus is that both conditions are accounted for. There's no question, it works.

Maybe I should get pictures...

Your trailer looks a bit heaver then mine. It's still possible, but the size of the metal is important. Man, I wish I studied ME, rather then EE, and music. :)

It always easy on paper. :)

[ntsqd]

The TrailBlazer I posted about being loaned in that thread has it's new frame built such that the tongue telescopes. The "receiver" tube runs from the very front of the rigid tongue part of the frame clear to the rear & sticks out a scosh so that there is a socket on the rear of the trailer too. (Battery cabling was run so that a receiver winch can pull on the trailer from the rear.)

2nd on the pictures, I should do that too.

[Rezarf <><]

Here is the final decision, mostly inspired from a relook at Kurt's trailer and Wildyotes trailer...

A single 2.5" structural square tube with .25" wall. This will eliminate a bunch of fab work and geometry at the front end. It will also be the easiest to get really really square. There won't be more than 120lbs on the tongue at its HEAVIEST, so all the extra steel just isn't needed.

This also allows me to use a ball coupler on road, and then unpin and install a lunette ring for light trail work. I have a ball/pintle combo. In addition, the ability to do a 90 degree jackknife is possible with this setup.

The drawbar will be fully welded through the front and second crossmembers.

I will "gusset" the draw arm with 2" HREW tubing with .125" wall bent up on a bender, and the basket will sit on top of it. Clear is mud? The draw bar will be welded at each intersection of the crossmembers.

What do you think?

Thanks!

Drew

[Rezarf <><]

Whoops, forgot to attach...

[ntsqd]

Highly suggest spending the $30 on the second of the two books I linked. Then you'll know whether or not that is enough. Dimension is always better than wall thickness, but at some point it doesn't fit. That's where the techniques in that book come in handy.

[Rezarf <><]

Does the book get into this aspect? Could you look through it and give me your opinion based on the data? I have failed to find that book at a few different stores now.

Thanks!

Drew

[ntsqd]

I've never found it in a store either. I ordered my copy from Northern Tool though I have found it on Amazon too.

There is enough info needed that it would be difficult to try to work it thru on a forum. Would be better to work it thru & then show the results for check-off & suggestions.

[cruiseroutfit]

Good idea on the tongue re-design... my first rendition of the trail trailer (circa 2000) had a standard tongue, similar to your option 2. I didn't actually have a complete welded joint, I notched the frame, heated it at the bend and then bent the two sides in, then welded the joint. Strong enough if done properly. This was actually just away to get it mobile. At the time I was still running the FJ55 rear axle that was bolted underneath it :D

It was several years later that I removed the old tounge and added one long enough to jacknife without damage. SOOOO crucial IMHO... mandatory in a trailer that is intended to be used in anything tougher than a 3 rated trail as I see it. I have encountered numerous times that I needed to be able to really back it up "tight".

I've been extremely happy with my tounge length, it tows nice, does great "tracking" offroad (I went with a slightly narrower axle for this reason). I have ~3500 miles on mine... all either on the trail, or enroute to the trail, no failures yet (crossing fingers :sombrero: )



As for the "engineering" behind the different tounge designs... I can't say I have put alot of thought into it, but all of the options you have presented could easily work with proper material selection and construction. While I respect what a book might have to say in relation to building a trailer, they are not likely taking many aspects into consideration (such as clearance, the jackknife factor, etc).

[ntsqd]

All the book does is make sure that the design can support the load w/o failure and that it will tow properly on the hiway. It does this in layman's terms, enough so that I used the book to help me understand Statics when I was taking that class. The book did a much better job of getting the ideas across than the class text & w/o burying it in Engineer-Speak.

The off road considerations are not considered or even mentioned, but those goals really aren't at odds with the goals of the book.

[cruiseroutfit]

All the book does is make sure that the design can support the load w/o failure and that it will tow properly on the hiway. It does this in layman's terms, enough so that I used the book to help me understand Statics when I was taking that class. The book did a much better job of getting the ideas across than the class text & w/o burying it in Engineer-Speak.

The off road considerations are not considered or even mentioned, but those goals really aren't at odds with the goals of the book.

Sounds like a good book, don't get me wrong... I'm just saying that either of his designs could be fabricated (engineered) to hold the intended loads with a SF included. When it comes to a trailer, I am less worried about statics and more so worried about dynamics ;) Engineer speak it is :D

[ntsqd]

I don't disagree that they could as I've seen some that worked, but those that failed in one way or another are more common. The author, an P.E.- M.E. with trailer design history, specifically warns against that type of layout. Mostly, as I recall, from a concern about dynamic loadings - both vertical & horizontal. Obviously if the bending strength of the structure at that point is high enough, then there's no problem.

When I worked the Shear-Moment diagram for CSUC's HEV APU trailer frame (of the basic design type in question) the front edge of the box/platform was a surprising hot spot. Since that is the only time I've done that exercise for that type of application, I do not know whether it is the exception rather than the rule. Seemed more conservative to assume that it's the rule.

Crudely put, Dynamics are nothing more that Statics multiplied by acceleration(s). A Statics study, with appropriate Factors of Safety and suitably adjusted loads & given that it will likely be over-built anyway, I believe is sufficient for this application.

[cruiseroutfit]

I don't disagree that they could as I've seen some that worked, but those that failed in one way or another are more common.

How many have you seen fail in this manner? I known of a dozen+ homebuilt trailers that get used off-road... I have seen zero frame failures... and most are using the simlple single beam tongue design with adequate fabrication techniques.


The author, an P.E.- M.E. with trailer design history, specifically warns against that type of layout. Mostly, as I recall, from a concern about dynamic loadings - both vertical & horizontal. Obviously if the bending strength of the structure at that point is high enough, then there's no problem.

Well, I still can't comment on the contents of the book nor the validity of the authors assertions. But I am willing to bet he was assuming trailers designed to carry heavy cargo, such as automobiles, construction debris, tractors, boats, etc.... The average off-road trailer has a maximum load capacity of ~500lbs give or take, versus 7k+ for a standard trailer. I stand by my assertions (both as a trailer owner and an Engineer) that either design would be fine for the loads a off-road trailer will encounter... simply put.


When I worked the Shear-Moment diagram for CSUC's HEV APU trailer frame (of the basic design type in question) the front edge of the box/platform was a surprising hot spot. Since that is the only time I've done that exercise for that type of application, I do not know whether it is the exception rather than the rule. Seemed more conservative to assume that it's the rule.

I am not even going to waste my time doing a SMD, if I was even remotely worried about the construction of the trailer I would model it in an FEA software and test it... but that is a waste of time IMHO.


Crudely put, Dynamics are nothing more that Statics multiplied by acceleration(s). A Statics study, with appropriate Factors of Safety and suitably adjusted loads & given that it will likely be over-built anyway, I believe is sufficient for this application.

No need to school me on the differences, I spent 5 years playing with them ;) But I would never discount statics over the use of dynamics in such an application. The loads experience by different components can be mulitplied over and over when you consider an off-road trailer bouncing down the road or falling down a 3' ledge.

Disclaimer: Trailer frames are NOT the area of engineering I studied by any means... while I spent considerable time with chassis construction, suspension, FEA, etc... I havn't done anything with trailer loading past some dynamics problems several years back. So take my opinion with a grain of salt ;)

[ntsqd]

I really haven't been keeping count. I'd guess somewhere btwn 1/2 dozen & 1 dozen that I've personally seen plus those photo documented floating around the net, plus those used as examples in the book. Note that these are trailers in general, not OR specific. Usually they some basterdized contraption made from what ever that was laying around.

The adequate fab techniques statement is the crux of the situation. It has been my observation that good fabricator can build things that work & live w/o the benefit of an Engineering degree. The TrailBlazer (http://www.expeditionportal.com/forum/showpost.php?p=73484&postcount=18)in my driveway is a prime example of this. The guy who built the frame under it did so with only what he learned working in the oil patch. It has 2 or 3 full penninsula runs plus a several weeks long trip into the Copper Canyon region under it's belt. The only detectable damage of any sort is the rock chipped paint, & the cracked tub perimeter aluminum frame - which he had nothing to do with.

I think FEA is a fine tool if properly defined. Too easy to GIGO for the casual user. The more involved the model & loading, the easier this is. Since I don't use it everyday I personally would be hesitant to solely use it's results as validation of my design.
A Shear-Moment Diagram is something nearly anyone can do with a little guidence, and it gives a simple graphical idea of where the frame needs more or less strength. The book does an admirable job in that guidence, or I found it to be so for me. I encouraged consulting it b/c absent the fab experience to make those judgement calls it offers the builder a tool to justify or negate what ever design decisions he/she has made. It is certainly not the only way to do things.

It has been a while since I read thru this book, but while most of the examples do tend toward your assumption, the stated intent is that a successful design can be had for any loading.

I wasn't stating the difference btwn Statics & Dynamics for your benefit as I was quite sure you more than knew the difference.

[Bob_Sheaves]

Just a sidebar....


FEA usually means Finite Element Analysis to the uninitiated, but to those that use it every day it also means:

F*&kedup Every Analysis :sombrero:

Seriously though, it is nice to be able to read a board with people on both sides of a discussion that know what they are talking about. For me, I'd like to interject a third opinion, that is to say, IF you are going to design a trailer (or complete vehicle) for the absolute balance of weight and load carrying capacity (such as used in military trailers) FEA, as well as Dynamic analysis are required, simply because it is a dang sight cheaper to cut, weld, and break electrons than it is any other material, IF you have the tools and understand their use and limitations. Having someone analyse you design is not too big a deal-I know several companies (including my own) that make a living out of doing just this. The cost for some is too high....until they get into an accident and a sharp lawyer finds out that a "homebuilt" is involved. The cost for a pro to analyse your design is peanuts compared to the costs of liability.

Best regards,

Bob Sheaves
CEO
catNET Incorporated
http://www.catnetsolutions.com

[Rezarf <><]

Man, I leave for a day and I come back to an engineer pissing contest! That was awesome!:bowdown: :D

Seriously though, Kurt, I highly value your imput, you use and built your trailer on a similar basis that I plan on using mine. Extended multiday trips in the Utah/Colorado area.

That said, saftey to me and others is my first and paramount concern. But the fact is this will be a light trailer, around 1200# complete and full of all fluids and gear, including the trailer.

I have a friend at Agco, that I might ask to run the FEA on, but he usually laughs at how I like to overbuild stuff and tells me, "what are you thinking, you don't need to run ______ thickness! You can get by just fine using this ______ thickness." I almost always over build my junk, but weight is an issue here. That said, he isn't familar with the flex that can occur when trying to get up the first switchback on Elephant hill with a trailer in tow... well actually he does, we have hit that trail together. Anyhow, equations and the real world don't always play fair with one another.

Kurt, what deminsions are you running on your trailer tongue? It looks beefy.

If I run with a single draw arm, I can always retro fit side supports like an A design if I start to show signs of torsional flex in the main tube. But it will only be free standing for 24" overall, it is hard to think that I could have a failure in that amout of space.

Thanks guys, I appreciate your opinions... even if I don't speak your language, I am a humble Industrial Designer...

Drew

[Grim Reaper]

This thread has my interest as well. I have a little enclosed trailer I picked up and yesterday was the first real road time I have seen with it. I proably had about 300-400lb of cargo (including a Deep cycle battery agains the front wall to run my fridge) with it mostly loaded in front of the axle.



The way the draw bar is attached made the trailer bounce excessively when it bucked. If you hit its correct harmonic with the bumps, weight and speed it was VERY annoying. It was right at about 55mph it was giving me motion sickness. 70 It was smooth and 45 it was tolerable.

I had planned on changed the hitch at some point but after yesterday it is more of a priority. The trailer has a VERY short hitch. Great for drafting the tow on the hwy and minimizing wind drag but it is an absolute pain in the back side to back up.

The problem is the current design. The hitch is welded to the front frame rail (2x2), then to a C Channel floor support about 12 -14 inches back and then to a piece of 2x2 angle iron that is just in front of the forward spring mount. Just too much flex in the Angle iron and C channel so it acts like a big torsion spring. Weight on the ply wood floor adding to the effect.

I think a A Frame where it directs the load back into the main side rails will be the best way to fix the problem with the least amount of weight added. Then make an extendable Tongue much like in the trailer ntsqd showed to fix the backing up maneuvering problems I am having. Replace the Angle Iron with 2x2 or 2.2.5 (to accommodated the 2x2 extension) to remove the flex and triangulate the center tongue bar that will have the extension.


possibly move the axle forward ( I may build an air ride set up like AT has) to offset some of the tounge weight when I mount a battery, propane tanks and possibly a water tank on tounge.

Any thoughts on this?

[Mike S]

When I designed my trailer, I included a length adjustable tongue with a swiveling HD pintle lunette. The main beam is supported at the sides by frame extensions that hold a Delta aluminum tongue box (this carries batteries, charger, water pump, and dual tool trays). The frame and tongue are built of 1/4" wall 2" ID square steel tubing. The lunette is attached to the end of a 5 foot tube of 2" OD 1/4" wall square tubing that slides into the main beam, and is held in place by a 1/2" pin through the main beam of the frame.

This set up has a couple of advandtages - at least one of which I did not think of when designing the trailer.

1. The trailer may be towed close up to the 'Cruiser on the highway, and extended out so that on a trail in a jackknife manouver the trailer body and frame do not contact the body or bumper of the 'Cruiser.

2. The tongue may be removed for security - and locked in the trailer.

3. When the tongue is removed, the trailer is nearly 2' shorter, so stowing it in the garage or driveway takes less space.

4. By simply drilling additional pin holes the length is infinitely variable up to about 55"

5. It is easily replaced and another tongue (with a drop hitch, ball coupler. etc.) may be installed in seconds.

We thought about this quite a bit before we started building, and I think we did a good job. I would love to have the susension of a Chaser, but I built mine before that was designed and tested.

I tried to balance the loaded weight by putting two fuel cans in front of the axle, and two to the rear of the axle. The 38 gallon water tank is between the frame rails, below the bed, and to the rear of the axle. Batteries and tool tray are in the tongue box. Spare is mounted ahead of the tounge box. I estimate the loaded weight at 1200 to 1500 lbs., and the tongue weight at about 150 ls.

Mike S

[Rezarf <><]

Mike-

You gotta post up a pic of the front of the rig! I like that design idea for sure. The swapping/removal thing was HUGE for me in doing this.

Thanks man!

Drew

[ntsqd]

A little while ago I posted pics of the trailer I referred to earlier in this thread here:
http://www.expeditionportal.com/forum/showpost.php?p=73484&postcount=18
It has most of those same features. One of the biggest deviations is that the sliding tongue has a socket receiver on it. This allows easily changing the coupler type by pulling a normal socket receiver pin. The idea was to beta test a coupler design I had to the point of doing the analysis on when I discovered the Lock-n-Roll (http://www.locknroll.com/) patent. Though I feel it is inferior in it's rotation design (essentially a rivet in tension) it pretty much killed my concept.

However, the trailer has been a great trailer and the frame is probably oil-field stout. :) Note that the tube that the coupler is pinned to extends completely thru the frame past the rear-most cross member.

[Xtreme XJ]

Which would you run? The first or the second?...

The first one has better triangulation of the chasis, at the cost of a useable platform in front of the "box."

Rez
This might be a little late in your design and not totally related, but how about adding a 2x2 receiver to the point where the rails come together at the lunette, that way you could have both a normal coupler for the ride to & from then a lunette to slide in for the rougher trails.
You could add a crossmember midway back to the tub which would help support the rear of the 2x2 tubing AND add support to the "A" area of the frame.... of the two drawings I might go with #2.
I'm enjoying this site (2nd. post) and it's trailer builds... I too some day want to build one...
Thanks for the great ideas and good luck with the build.....

Curt (with a "C")

[Rezarf <><]

Curt, Thanks for the imput. There is a third design in question check it out and let me know what you think.

ntsqd, that trailer is beefy! I don't see many differences for what I want to do, I will have the same amount of front end hanging off as the trailer picture and I will be adding crossmembers that triangulate the designs in question. How about a few more trailer pics? :D

Thanks!

Drew

[ntsqd]

I took those pics of it shortly b4 posting them and they're currently all that I have. I'll take more if you can tell me what you want to see. Distance for perspective might be an issue as I got trucks apart on both ends of it in a one lane driveway, but transfer case parts for the 'land-locker' & tow rig Suburban should be here tomorrow.

It is stout, but not particularly heavy. I don't think I want to tow it up the hill into the desert with my yota mini, but it did just fine around town and that was b4 I removed all of my friend's camping gear from the bottom.

[Mike S]

Mike-

You gotta post up a pic of the front of the rig! I like that design idea for sure. The swapping/removal thing was HUGE for me in doing this.

Thanks man!

Drew

Drew

My Windows machine is fried. I am now setting up a new Mac Book Pro and don't have access to my stash of photos until I rescue the contents of the PC hard disk.

I definitely sucks, but I am stuck ntl I get it done. I will try to take some new photos for you. The system I described really works well, and is simple to build.

Mike

[Rezarf <><]

I took those pics of it shortly b4 posting them and they're currently all that I have. I'll take more if you can tell me what you want to see. Distance for perspective might be an issue as I got trucks apart on both ends of it in a one lane driveway, but transfer case parts for the 'land-locker' & tow rig Suburban should be here tomorrow.

It is stout, but not particularly heavy. I don't think I want to tow it up the hill into the desert with my yota mini, but it did just fine around town and that was b4 I removed all of my friend's camping gear from the bottom.

Yeah, I relooked at your trailer, I can see how short your tongue is too. I thought it was a bit longer last time I looked.

Thanks for all your opinions!

Drew

[Rezarf <><]

Drew

My Windows machine is fried. I am now setting up a new Mac Book Pro and don't have access to my stash of photos until I rescue the contents of the PC hard disk.

I definitely sucks, but I am stuck ntl I get it done. I will try to take some new photos for you. The system I described really works well, and is simple to build.

Mike


Ouch, man I hope you can recover all your information and files Mike! If you get some time down the road, I would love to see it. I am going with the single draw arm out front, I have checked it out with a few enginerds now and they have each given me a green light.

Thanks man!

Drew

[ntsqd]

Yeah, I relooked at your trailer, I can see how short your tongue is too.
I wouldn't call it short, un-extended it makes up roughly 1/2 the tow ball to axle length. Extended it is ~3/4 of that length.
The Extendable Tongue:
http://i168.photobucket.com/albums/u196/ntsqd/TB-TongueExtended.jpg
Can also see the receiver socket best in this pic. There is a normal trailer coupler on a section of tube to tow with. There was also a Ring but with the Original Owner's untimely demise I suspect that it has been lost. I do have the pintle coupler, probably should buy a ring just in case. The short section of tube sticking straight up off the socket is for the landing jack's caster wheel.

[Xtreme XJ]

I wouldn't call it short, un-extended it makes up roughly 1/2 the tow ball to axle length. Extended it is ~3/4 of that length.
The Extendable Tongue:
http://i168.photobucket.com/albums/u196/ntsqd/TB-TongueExtended.jpg
Can also see the receiver socket best in this pic. There is a normal trailer coupler on a section of tube to tow with. There was also a Ring but with the Original Owner's untimely demise I suspect that it has been lost. I do have the pintle coupler, probably should buy a ring just in case. The short section of tube sticking straight up off the socket is for the landing jack's caster wheel.

Now that's versatility......


Curt :safari-rig:

[cruiseroutfit]

Wow, I came back to this thread today and there was alot of discussion I seemed to have missed. I'll play catch up here.


I really haven't been keeping count. I'd guess somewhere btwn 1/2 dozen & 1 dozen that I've personally seen plus those photo documented floating around the net, plus those used as examples in the book. Note that these are trailers in general, not OR specific. Usually they some basterdized contraption made from what ever that was laying around..

I guess the term "apples and oranges" comes to mind here. I too have seen plenty of "trailers in general" fail, but none of those would qualify for my definition of "built to a worthy standard" let alone built for the rigors of offroad use. I had a commercially built car hauler that started experiencing cracking where the v-style tounge met the deck construction of the trailer... failure. My opinion that a "single tongue" trailer can be built and used is assuming that proper fab techniques are used... plain and simple. If crappy construction is combined with crappy material secection, any design can fail.



Kurt, what deminsions are you running on your trailer tongue? It looks beefy. ...

Once again sorry for the late response, it is 3.5" x 3.5" - 3/16" wall. More than adequate for the job.


If I run with a single draw arm, I can always retro fit side supports like an A design if I start to show signs of torsional flex in the main tube. But it will only be free standing for 24" overall, it is hard to think that I could have a failure in that amout of space...

Absolutely, your first rendition doesn't have to be your final... mine sure wasn't :D

[ntsqd]

Finally tracked down my copy of Smith's book. His main objection to a non under-lapped tongue stems from the large twisting, bending, & pushing loads in that area. By promoting an under-lapped tongue he gains many inches of weld seam and Moment of Interia in this, as he puts it, "critical area".

That being said, I've never said that a non under-lapped tongue wouldn't work, just that it should be approached with caution. My desire & intent is that said caution will produce the necessary level of design, material choice, and fabrication for the trailer to be safe & a success.

If we can't agree on that then we'll have to agree to disagree. :)

[Rezarf <><]

That being said, I've never said that a non under-lapped tongue wouldn't work, just that it should be approached with caution. My desire & intent is that said caution will produce the necessary level of design, material choice, and fabrication for the trailer to be safe & a success.

If we can't agree on that then we'll have to agree to disagree. :)

Nobody is disagreeing with that! :D

I have decided on the single draw arm, I have 3" square tubing with .25" wall with a 2.5" sliding tongue...

It will be triangulated but not to the coupler.

As soon as my travels slow down I will be starting.

Thanks!

Drew