Extendable Tongue Explanation

[efelker]

I've read several times how Oliver's Extendable Tongue can eliminate the need for a WDH and/or Sway bar. Anyone want to offer an explanation of the physics involved in why this is so (physics and mechanics were not my trump suits in college)? I can understand how lengthening or shortening the tongue can change the moment of inertia and thus mitigate the point at which sway can occur -- but I'm clueless on how changing the length distributes the load. I would have thought by making the tongue longer the net effect of the weigfht on the hitch would increase.

 

Looking for the "Physics for Dummies" explanation.

 

Ed

[mountainborn]

ED,

I'll give er' a try. Semi tractor trailer rigs, eighteen wheelers, are weighed carefully by many states during their cross country travels. Many have a sliding fifth wheel, which is where the trailer pins to the tractor. On many trucks this fifth wheel assembly will slide. This allows the trucks weight to be made "legal" on each axle. Instead of the entire payload being on the trailer, which could result in the trailer axles being over weight, more of the weight can be moved to the truck by sliding forward. This will even place a part of the load on the steering axle.

Moving the fifth wheel to the rear, results in less weight on the steering axle, and when the trailer is empty, "tugging" can be reduced or eliminated by sliding all of the way to the rear.

Since when we tow, we are dealing with three single axles, and reap the benefits of improved gas mileage, weight distribution is important to us.

ED, I am afraid this isn't the engineering or mathematics answer that your question deserves, but, it is as close as this ol' hillbilly can get. I think that most of us would like to get a better grasp of this issue, so here's hoping that others will post on the subject.

[mountainborn]

Here is a look at our tongue extended all the way out. Note the two holes in the tongue where the lock down bolt goes, torque rating ninety pounds. We extended the tongue all the way out in anticipation of installing our generator on the tongue, using those bolt holes.

[tumbleweed]

Being a FIRM believer in sway bars, I hope someone from factory will wade in with a "Redneck" understandable explanation to this phenomon!!!! Please!!!

Chuck

[Oliver Travel Trailers1571927901]

A lot of research went into the frame design. The backbone of the trailer is the use of a 2”x5” box aluminum with welded aluminum cross members. Towards the front area leading to the hitch is additional reinforcement with the 2”x5”as well. This creates a solid frame that resists flexing and encourages the trailer to track behind the tow vehicle. Then for even more strength the lower outer shell actually fits over the frame with channels designed into the mold. Fiberglass is very strong as many of you know. With these features it’s been the experience of most people that they do not require a sway control system or a load distribution devise. (The extendable tongue)

 

With this said I must point out that many other factors such as the tow vehicle, how the trailer is loaded etc… factor in. At the plant I suggest to new owners that this is their decision, try it out and if it’s needed, then add them on.

 

I think we all agree that safety must be 1st so do as you feel is best.

 

I’ve loaded up some pictures at our Photobucket site under “frame” that will show you the difference in our frame and what's commonly used by some of the other trailer manufactures.

 

http://s262.photobucket.com/albums/ii12 ... tee/Frame/

[mountainborn]

Holey toledo ! I have never seen those photos side by side.

No words or captions needed, the photos speak for them selves. Thanks for the link, Robert.

[efelker]

OK, it's been a while since I looked at these responses, but let's try again --

 

1. Does shortening the tongue put more weight on the hitch ball than lengthening?

2. Does shortening the tongue reduce the tendency to sway?

 

I would want to keep my tongue weight as low as possible with the least tendency to sway -- so would the tongue be in or out?

 

Towing, weights, sway and all the physics associated with that stuff just makes my hair hurt!!!

[mountainborn]

efelker said:

1. Does shortening the tongue put more weight on the hitch ball than lengthening?

a. Yes

2. Does shortening the tongue reduce the tendency to sway?

b. No, but the most common sway contributor is too much weight behind the trailer axle, which will have the effect of lifting up on the trailer hitch ball. ( making the rear of the tow vehicle lighter )

I would want to keep my tongue weight as low as possible with the least tendency to sway -- so would the tongue be in or out?

ED, I think that hasn't mattered much to butcherknife and I. We have towed both ways, in and out. Also with the generator on the tongue and off of it. Without the even the slightest hint of sway.

One sure way to reassure one's self about the tongue weight is with a Sherline tongue weight scale. Here is a link to the manufacturer:

http://www.sherline.com/lm.htm

The last time I priced them they cost around $100. it looks like this:

[efelker]

Mountain:

 

Thanks for the info. With the Highlander it looks like it just isn't going to matter, and we probably won't need a WDH unless the headlights are pointing at the Big Dipper when we hook up based on the suspension capacity of the Highlander.

 

It seems like everytime someone asks about tow capacity, tongue weight, and sway on most RV forums you get the Noble Prize in Physics explanation. I liked your "down home" explanation.

 

Thanks.

 

Ed & Bev

[efelker]

Tom:

 

If I had my druthers it would be the hybrid -- but its max tow rating is only 3500 lbs and I'd like to stick with the 5000 lbs on the regular Highlander. Plus, Toyota is real-l-l-l proud of the Highlander Hybrid -- like $40,000 plus proud for the Limited. I just want to buy a car, not become part owner in the company -- so I'll stick with the regular Highlander.

 

But all things given -- wouldn't it be great to have a SUV type vehicle, with either 4WD or AWD, that gets 30+ mpg in town, 28-30 when on the highway, and tops 24 mpg when towing?

[bugeyedriver]

OK, it's been a while since I looked at these responses, but let's try again --

 

1. Does shortening the tongue put more weight on the hitch ball than lengthening?

2. Does shortening the tongue reduce the tendency to sway?

 

I would want to keep my tongue weight as low as possible with the least tendency to sway -- so would the tongue be in or out?

 

Towing, weights, sway and all the physics associated with that stuff just makes my hair hurt!!!

 

Greetings to all from the Texas Hll Country where I'm nestled amidst about 150 friendly Casita owners at the Texas Bluebonnet Rally!

 

I believe I can provide a definitive answer to this . . . There's a guy here with the device Mountainborn mentioned for getting an accurate tongue weight. Currently, my tongue is on the middle of three settings due to the added aluminum box I asked to be fabricated to accommodate my Honda 2000 generator. it is strapped down with two ratchet straps and secured with two lockstraps. Gas is full, I guess its about an additional 75 lbs of weight hanging out in front of the leveling jack.

 

Trailer is loaded for travel and Oscaar is sleeping peacefully on the bed over the axle. Fresh water = 50% / Grey = 50% / Yucky = 29%.

 

Tongue weight = 400 lb.

 

After moving the tongue OUT to the final position tongue weight = 380 lb.

 

Proof positive that extending the tongue lessens tongue weight. Don't ask for the nuclear physics behind how it works, I just read the numbers!

 

SSSSSOOOOOOOOO . . . tongue out = less tongue weight.

 

I understand about 10% of the trailer weight should be on the tongue and that if you get it TOO light you "may" encounter stability problems.

 

Tongue extended also provides an easier back up experience for some because it is less likely to over-correct when changing directions.

 

ps I am lovin' life LARGE in my new trailer

[earthdancer]

Hi Pete!!

Glad you're having a good time at BlueBonnet! Ifn' ya' run into a couple walking a cat in a stroller(I have NOT been drinking) tell 'em Chuck said Hello and will see them at Lake San Antonio. Check out Jerry the cat, he is as cool a cat as you will ever meet!

Thanks for sending the tongue wgt info!

Regards, Chuck

[bugeyedriver]

Chuck,

 

Jerry and his cat-mobile have been by and his owners give you their warmest regards. Sometimes Jerry sits inside and other times he rides on top and seems to point out the direction to go!

 

Jerry & Oscar get along well also . . .