Trailer hitch connection?

[ntsqd]

Aside from the occasional "klunk" from the origonal setup on my M416, Do they have any issues? Seems to me it's a very stout design. I have more or less eliminated the klunk by installing electric brakes controlled by a Tekonsha Prodigy. It is one of the best brake controllers I have ever used.

They're pretty close to Soldier-proof, which says a lot.

http://www.expeditionportal.com/forum/showpost.php?p=78977&postcount=27
I believe what Bob is saying here is that because there is actual slop in the coupling it does not have any built-in damping. A ball-coupler has a fair amount of friction in it, which could serve to damp trailer oscillation. At some point the trailer's inertia exceeds that damping ability and that is when you see various "anti-sway" devices in the trailer to tow rig attachment. I suspect that the formula that predicts total vehicle system maximum safe speed has a variable for this damping tendency, but I'd have to look it up and we're not likely do to that calc anyway.

Speed will be the critical factor. At some speed all trailer systems become unstable. Above that speed the oscillation will feed itself & become progressively worse, in certain cases this is true even if the speed is held constant. What's important is that this speed be far above any speed you're ever likely to go.

 

[Martyn]

Note that the Lock-N-Roll's that come set up to slide into the trailer tongue have the 2" tube bulged at the end to give clearance to the 'rivet head'. If your attachment point has a larger opening than what the 2" x .250 wall tube offers it shouldn't be any trouble.

We sell a lot of the Lock-N-Roll couplers, in fact I think we are their biggest retailer, We used to see the issue of the bulge in the coupler coming into contact with the inside of the receive tube wall, not allowing it to slide all the way in. It was easily solved by grinding a little on each side so it fitted.

The new batches of Lock-N-Roll couplers haven't exhibited this binding, I think they have made the tube a little longer and placed the location hole a little further back to solve the issue.

We really like this coupler, it's certified for use on road, simple to use, built like a brick **** house, allows for a great range of movement and is not prone to binding. We also have very very few issues with the product so it's an easy item for us to sell.

 

[ntsqd]

Martyn,
FWIW The one I have came from you, indirectly. My friend Rod Michael bought one of your trailers (in Viper Yellow), and of course he got one of the Lock-n-Rolls to go with it. I was given it to study while Rod was alive. After his death the YJ & trailer were sold and I've still got the L-n-R with no idea who bought the vehicles.

Anyway, it has the swaged or bulged tube end, which is how I knew of the potential issue.

 

[Martyn]

Martyn,
FWIW The one I have came from you, indirectly. My friend Rod Michael bought one of your trailers (in Viper Yellow), and of course he got one of the Lock-n-Rolls to go with it. I was given it to study while Rod was alive. After his death the YJ & trailer were sold and I've still got the L-n-R with no idea who bought the vehicles.

Anyway, it has the swaged or bulged tube end, which is how I knew of the potential issue.

Rod's death was really a shock for us at AT. We are a tight knit group and when something like this happens it's very sad. We all took a little time to reflected on what are the important things in our lives and set about prioritizing them. Invariably they were family, and trying to spend more quality time doing the things we love, like Overlanding.

Sorry you lost a good friend.

 

[Bob_Sheaves]

They're pretty close to Soldier-proof, which says a lot.

http://www.expeditionportal.com/forum/showpost.php?p=78977&postcount=27
I believe what Bob is saying here is that because there is actual slop in the coupling it does not have any built-in damping. A ball-coupler has a fair amount of friction in it, which could serve to damp trailer oscillation. At some point the trailer's inertia exceeds that damping ability and that is when you see various "anti-sway" devices in the trailer to tow rig attachment. I suspect that the formula that predicts total vehicle system maximum safe speed has a variable for this damping tendency, but I'd have to look it up and we're not likely do to that calc anyway.

Speed will be the critical factor. At some speed all trailer systems become unstable. Above that speed the oscillation will feed itself & become progressively worse, in certain cases this is true even if the speed is held constant. What's important is that this speed be far above any speed you're ever likely to go.

Correct on all counts. In addition, the longitudinal leverage ratio between the loaded CG of the trailer, versus the offset in the pintle pivot to lunette (see the previous images- the pivot center of the lunette does not corrospond to the pivot center of the pintle, by design), and the loaded CG of the towing vehicle figure into the equation. This is why the military uses (and requires) a driver to have calculated this information to determine convoy speed, if outside normal CONUS operations (meaning tactical deployment, not normal logistic transport). Refer to the data plates on the military trailers and vehicles for the proper calcs. The values used vary, depending on the type of vehicles used.

Best as always,

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

 

[elcoyote]

Martyn,
FWIW The one I have came from you, indirectly. My friend Rod Michael bought one of your trailers (in Viper Yellow), and of course he got one of the Lock-n-Rolls to go with it. I was given it to study while Rod was alive. After his death the YJ & trailer were sold and I've still got the L-n-R with no idea who bought the vehicles.

Anyway, it has the swaged or bulged tube end, which is how I knew of the potential issue.

We are in contact with Monty Boswell who bought both the Jeep and Horizon. We will be swapping out Overland for a EeziAwn T-Top. PM me if you'd like to get in touch with him.

 

[ntsqd]

PM sent.

Will the Overland be FS?

 

[Willman]

Here are some pictures of the completed Lock N' Roll hitch just incase you are not following my trailer build!!!

This hitch is the only way to go!!!!!

:jumping:

 

[Pskhaat]

Great information in this thread, almost to overload for me. What then is the most preferred attachment? I'm still trying to find out why y'all think the simple pintle and rolling lunette are flawed? I was seeing conversations about oscillation in the trailer (due to suspension I assume) and the pintle design contributes to this?

 

[Willman]

Great information in this thread, almost to overload for me.

Come on...your a Jensen!!!!!!:shakin:

What then is the most preferred attachment?

Lock N' roll is the only way to go on the 4x4 trails......

I'm still trying to find out why y'all think the simple pintle and rolling lunette are flawed? I was seeing conversations about oscillation in the trailer (due to suspension I assume) and the pintle design contributes to this?

Noise and the hitch movement.

The lock n' roll hitch is a solid connection with out the noise and movement you will get from a pintle. The lock n' roll fixs the problem that the old pintle style has with all the extra slop in the hitch.

Don't get me wrong...pintle is a good connection.....but if you are changing your hitch setup........Lock n' roll is where i would put my $$$$$.

 

[The BN Guy]

Thank you for posting that link! I've been seeing the Treg setup in A4WD Monthly but didn't know of anything here in the States.

 

[ntsqd]

Just looking at a lunette/pintle I expect it to be noisy, yet I've read where some folks say they aren't. Which leaves me wondering if some are and some aren't (& why), or if those who claim they aren't are tone deaf.

 

[ntsqd]

Soft springs can promote instability if not correctly designed & installed. Traditional trailer springs are designed to keep fatigue from killing the trailer frame, not allow the instability, and be cost effective to use b/c they require no dampers. Most trailer springs are designed to deflect 1" at their rated max load, and have up to 3" of additional travel for bumps.

I had a look at the formula that can be re-arranged to predict the maxium speed of any tow rig & trailer combo. There is no varible that represents any damping in the coupler, though there is a constant that is only noted as being 'empirically derived'. I suspect that a damping varible might be buried in that, but have no way to back it out. It's not that I think each and every trailer/tow rig combo should have this calc performed so much as I want to know how significant this damping is. If it is tiny then the Critical Speed of pintle/lunette shouldn't be much different than that of a ball coupler or a Lock-N-Roll. If it is as significant as I think it is then each coupler type will have a different Critical Speed and there potentially could be a large difference between them.

For those who might be interested, the formula is below. Everyone else will likely glaze over as it's going to be a mess. I don't blame them.

U = ((sqrt(L^3Y))/(sqrt(2Ih))/{d +(Io - (WtL^2)/g[H/100 - (H/100)^2])/Ih)(Wt/Wc)C}

Where:
U = Critical Speed
L = Tongue Length (hitch to axle, ft)
Y = Cornering Stiffness of Trailer Tires, lbs./rad
Ih = Trailer Moment of Inertia (about hitch, slug-ft^2)
Io = Trailer Moment of Inertia (about CG, slug-ft^2)
Wt = Trailer Weight, lbs.
Wc = Tow rig Weight, lbs.
H = Percent of Trailer Weight at Hitch Point
C = 3.7 (empirically derived)
g = Gravitational Constant, 32.2 ft/sec^2
d = damping ratio (set btwn 0 & 1)

A word on 'd', When at 0 any sway will not change for better or worse. When 1 any sway will rapidly go away. If set below 0 the sway will increase until something, like the guardrail or another vehicle, makes contact & stops it.

Good luck with a number for Y, none of the tire mfg's I spoke to would yield that sort of information.

 

[Willman]

Soft springs can promote instability if not correctly designed & installed. Traditional trailer springs are designed to keep fatigue from killing the trailer frame, not allow the instability, and be cost effective to use b/c they require no dampers. Most trailer springs are designed to deflect 1" at their rated max load, and have up to 3" of additional travel for bumps.

I had a look at the formula that can be re-arranged to predict the maxium speed of any tow rig & trailer combo. There is no varible that represents any damping in the coupler, though there is a constant that is only noted as being 'empirically derived'. I suspect that a damping varible might be buried in that, but have no way to back it out. It's not that I think each and every trailer/tow rig combo should have this calc performed so much as I want to know how significant this damping is. If it is tiny then the Critical Speed of pintle/lunette shouldn't be much different than that of a ball coupler or a Lock-N-Roll. If it is as significant as I think it is then each coupler type will have a different Critical Speed and there potentially could be a large difference between them.

For those who might be interested, the formula is below. Everyone else will likely glaze over as it's going to be a mess. I don't blame them.U = ((sqrt(L^3Y))/(sqrt(2Ih))/{d +(Io - (WtL^2)/g[H/100 - (H/100)^2])/Ih)(Wt/Wc)C}

Where:
U = Critical Speed
L = Tongue Length (hitch to axle, ft)
Y = Cornering Stiffness of Trailer Tires, lbs./rad
Ih = Trailer Moment of Inertia (about hitch, slug-ft^2)
Io = Trailer Moment of Inertia (about CG, slug-ft^2)
Wt = Trailer Weight, lbs.
Wc = Tow rig Weight, lbs.
H = Percent of Trailer Weight at Hitch Point
C = 3.7 (empirically derived)
g = Gravitational Constant, 32.2 ft/sec^2
d = damping ratio (set btwn 0 & 1)

A word on 'd', When at 0 any sway will not change for better or worse. When 1 any sway will rapidly go away. If set below 0 the sway will increase until something, like the guardrail or another vehicle, makes contact & stops it.

Good luck with a number for Y, none of the tire mfg's I spoke to would yield that sort of information.

WOW......your good!!!!!! Thanks for the post!!

Going to have to check that formula out.....where did you get that??

My rule of thum.....make sure your bearings are all packed....go the fastest you can safety without the trailer going all over the place.....I have found a great speed of 75 that works great for the tow rig and trailer!!!..going to have to try that forumla out to see what that says.....

 

[ntsqd]

It's from "TRAILERS; How to Buy & Evaluate" by M. M. Smith BSME, Techni-Visions, 1988, ISBN 0-914483-07-2