Need some help with my Trailer design

[slimtwo]

I tried doing a search to see if the question I have has come up before, however I didn't see it. I wonder if there is a rule of thumb concerning the length of the tung in relation to the length of the trailer. i have been doing some drawings to see what looks good, and what will work. I just want it to be correct. Any help would be appreciated.

Happy trails!

Bruce :1888fbbd:

 

[ex m38a1er]

I see you 're wheeling a tj just like i do and you have a trailer building in procces just like i do.
You can check my thread in the ODYSSEY trailer and you can get the dimensions for a trailer that will (hopefully) tow properly,have the same wheel track as a tj and will follow your tires track(exact) along the trail.
PM me whenever you fel like.
I'm really interested in your ideas and design
George:victory:

 

[ntsqd]

If you want to sort it out from an Engineering approach using only algebra and have an idea of what you're about:
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_12729_12729

Most will say 10-15% of the total weight on the tongue with 10% being the ideal. You can do this iteratively by moving stuff around until it works, or you can do it all on graph paper and then test it at 1:1 scale. The book above outlines the graph paper method. The cover illustration is the method's results.

An RoT that my grandfather used was no less than 1/3 of the total distance from the ball/coupler to the axle must be unladen tongue. It has worked on several trailers, but I can see that if the trailer loading is just right that it might fail too.

 

[slimtwo]

I see you 're wheeling a tj just like i do and you have a trailer building in procces just like i do.
You can check my thread in the ODYSSEY trailer and you can get the dimensions for a trailer that will (hopefully) tow properly,have the same wheel track as a tj and will follow your tires track(exact) along the trail.
PM me whenever you fel like.
I'm really interested in your ideas and design
George:victory:

I haven't done alot of wheeling in this Jeep yet, I've only had it a little over a year. Most of my experience is in my 65 Gladiator, but as soon as I sell it, I can build the trailer and do alot more. I'll send you a sketch of my idea for a trailer.

 

[slimtwo]

If you want to sort it out from an Engineering approach using only algebra and have an idea of what you're about:
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_12729_12729

Most will say 10-15% of the total weight on the tongue with 10% being the ideal. You can do this iteratively by moving stuff around until it works, or you can do it all on graph paper and then test it at 1:1 scale. The book above outlines the graph paper method. The cover illustration is the method's results.

An RoT that my grandfather used was no less than 1/3 of the total distance from the ball/coupler to the axle must be unladen tongue. It has worked on several trailers, but I can see that if the trailer loading is just right that it might fail too.

Thank you for the information, I'm gonna check to see if the library has a copy so I can check it out.

Happy trails!

Bruce

 

[shadowhaus]

Get it as close to your vehicle as possible without hitting. A longer tongue means the more the trailer track will cheat in a sharp turn and possibly get hung up or scrape against something. The closer the trailer tracks stay to the tow vehicle the better out on the trail.

 

[jcbrandon]

Get it as close to your vehicle as possible without hitting. ... better out on the trail.

Good advice for a trailer optimized for use on the trail. For highway use, a longer tongue will reduce the tendency to sway. These are mutually opposite design goals. The ideal design will choose the best compromises for its performance goals.

Designing a trailer is like any other design task, particularly those related to vehicles. All designs will involve compromises and trade-offs. There is no single correct answer.

A trailer that works great on the trail might be a pain to tow at freeway speeds. A design that tows well on the highway might be impractical on the trails.

If you are designing a trailer, establish your criteria and goals first. Then choose the best combination of compromises for your needs.

The trailer design and build book that ntsqd recommends is a great tool. It isn't a book of plans and it won't tell you how to build a trailer for a particular job. But it will tell you how to figure out what your trailer should look like. Beware however, that it is self-published. The editing is spotting. And it makes continuous references to companion books that you probably haven't bought yet. It is also difficult to find and somewhat expensive. But it is the best book on the subject.

 

[Martyn]

I haven't done alot of wheeling in this Jeep yet, I've only had it a little over a year. Most of my experience is in my 65 Gladiator, but as soon as I sell it, I can build the trailer and do alot more. I'll send you a sketch of my idea for a trailer.

Eye balling your drawings I'd say your tongue is too long.

In addition to what has been said about the trailer pulling inside the vehicle on turns, a long tongue results in a slower direction change when reversing.

I know that trailers that turn quickly in reverse take some getting used to, but in tight quarters you are going to want that responsiveness.

I'd agree with 10 - 15% tongue weight, in addition to that you want to be able to move the trailer easily by hand, by one person.

The temptation is to make a trailer that is big enough to carry everything including the kitchen sink. For off-road be a minimalist.

 

[slimtwo]

Eye balling your drawings I'd say your tongue is too long.

In addition to what has been said about the trailer pulling inside the vehicle on turns, a long tongue results in a slower direction change when reversing.

I know that trailers that turn quickly in reverse take some getting used to, but in tight quarters you are going to want that responsiveness.

I'd agree with 10 - 15% tongue weight, in addition to that you want to be able to move the trailer easily by hand, by one person.

The temptation is to make a trailer that is big enough to carry everything including the kitchen sink. For off-road be a minimalist.

Thanks Martyn, I agree with what you are saying, therefore, I am going to Shorten it up. That way it will work better in confind areas

 

[ntsqd]

The ISBN of the book is: 0-914483-32-3, but it would surprise me if any library had it.

An extendable/retractable tongue is one way to address both trail and highway towing needs. Other than for picture's sake I've yet to extend the tongue on the TrailBlazer, so I kind of doubt that it is a practical solution, but it is an option.

 

[slimtwo]

The ISBN of the book is: 0-914483-32-3, but it would surprise me if any library had it.

An extendable/retractable tongue is one way to address both trail and highway towing needs. Other than for picture's sake I've yet to extend the tongue on the TrailBlazer, so I kind of doubt that it is a practical solution, but it is an option.

That's not a bad idea, I forgot that I had seen something like that once before. Of course if you have never used the option before now, then I guess it might not be necessary.

Hey do you have any other pictures posted of the full view of your rig? I would like to see them, if you don't mind sharing them. And is this something that you built, or did you purchase it already done?

:1888fbbd:

Thanks!

Bruce

 

[ntsqd]

I've debated extending it for long highway tows, but it tows nicely enough collapsed that it seems kind of pointless. Where the extending tongue comes in handy is when the caster wheel isn't on the landing jack (I don't usually take it on trips) as then extending the tongue makes it easy to jockey the trailer around in camp.

This trailer is on long term loan to me. I'm hoping that the owner decides to sell it to me.
The frame was built by a local shop owned by a friend of both the owner and myself for the original owner, who has since passed on. It was designed for frequent trips to remote parts of Baja as the PO's passion was finding lonely surf & wave-ski breaks. Other than being pebble blasted on the leading surfaces it shows no sign of damage.
More pics:
http://s168.photobucket.com/albums/u196/ntsqd/Trailer Stuff/

 

[ex m38a1er]

Bruce ,
Here're a few rules of a thump for trailer designing:
-10-15 tongue weight as others have mentioned
-THe axle should be positioned in a 60/40 manner in the length of the tub
-The hitch to center of the axle=to your tow rig's wheelbase.(in order your trailer's track to be identicall to your towing rig's)
-For a tongue you can use a (single)straight tube an 'A' or a combination.
A lot of off roaders use a single because they don't want when jacknifing
their bumper to hit the side of the tongue.
I think all "A" tongue hitches come in a 50o set up and this pretty much dictates your tongue's lenght.

[/IMG]
(this comes i think from teardrop's forum)
Of course as many other fellows mentioned "ALWAYS" a design is a compromise.
NO having all the above in mind you can just copy the provem m101CND

[/IMG] and have sometimes problems swaying and manouvering
(I've been driving a m100 in the Greek behind a G-Wagen)
Or take some of the features of this

[/IMG](better for not so tight trails)
Anyway you're driving a SWB Jeep and it wouldn't make along combo.
Whetever you go with have fun
George

 

[R_Lefebvre]

Am I alone in thinking that, when we're talking about a relatively light weight trailer like these, being towed behind a truck, that the tongue weight really isn't that critical? In my mind, the requirement for tongue weight is to put enough weight on rear axle of the tow vehicle to give it the traction it needs to stop any swaying or jacknifing forces.

If you've got a 5000lb F150, and a 10,000 travel trailer, that 1500lbs tongue weight is really needed on the back axle to resist the lateral forces.

But, with a 1000lb trailer on a 4000lb expo truck, whether you've got 50 or 150 lbs of tongue weight just doesn't seem to be a big deal?

 

[Martyn]

Am I alone in thinking that, when we're talking about a relatively light weight trailer like these, being towed behind a truck, that the tongue weight really isn't that critical? In my mind, the requirement for tongue weight is to put enough weight on rear axle of the tow vehicle to give it the traction it needs to stop any swaying or jacknifing forces.

If you've got a 5000lb F150, and a 10,000 travel trailer, that 1500lbs tongue weight is really needed on the back axle to resist the lateral forces.

But, with a 1000lb trailer on a 4000lb expo truck, whether you've got 50 or 150 lbs of tongue weight just doesn't seem to be a big deal?

It sounds good in theory, but in practice it's very complicated.

Here are some simple reasons for sway:

For the tow vehicle...

1) Wheelbase is too short
2) Rear overhang is too long
3) Rear suspension is too soft
4) Rear-end weight is too much
5) Rear cornering stiffness is too low

For the trailer...

1) Tongue weight is too little OR too much
2) Center of gravity is too high
3) Tongue length is too short
4) Trailer frame is too flexible
5) Trailer suspension is too soft

My favorite is "1) Tongue weight is too little OR too much" so I gather it just has to be spot on :sombrero:

And of course we haven't even mentioned tires or tire pressure as a cause for sway.

The advice is to keep the tongue weight at 10-15% but you have to search hard to find a reason for doing so. Your reasoning for tongue weight is very plausible.

The rear axle can be considered a rotational point, and the ball coupler a second point, weight on the ball would help to stabilize the axle. But how do you then explain that too much tongue weight can cause sway?