Tongue Weights - Page 4 - Fiberglass RV


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Old 08-26-2012, 03:41 PM   #43
GPJ
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I am really enjoying this discussion. The references to Mr. Gratz's explanations help bridge the gap between theory and practice, although it takes a fair bit of time to wade through the math with a couple of real world examples. Finally a relatively easy way to understand why tongue weight (or rather what tongue weight indicates) is important!

After a couple of hours with my pencil and calculator, I will now take cpaharley2008's advice and have a beer!
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Old 08-26-2012, 04:24 PM   #44
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Originally Posted by cpaharley2008 View Post
All of this technical stuff is giving me a headache, I either need some aspirin or
Me to but at this point would prefer a little tequila over beer!
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Old 08-26-2012, 04:57 PM   #45
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Originally Posted by Carol H View Post
Tom, Mr. Gratz's explanation is actually a pretty good/clear one. ..........
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Originally Posted by Carol H View Post
Me too but at this point would prefer a little tequila over beer!
I'm sitting here waiting for Carol's simple explanation of the dynamics of trailer sway. In 25 words or less.
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Old 08-26-2012, 05:03 PM   #46
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Originally Posted by Thomas G. View Post
I'm sitting here waiting for Carol's simple explanation of the dynamics of trailer sway. In 25 words or less.
Cant be done! at least not by me!
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Old 08-26-2012, 07:01 PM   #47
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Floyd,

What is your tongue weight with bikes?

Thank you
I did not weigh it today, but it is around 250 pounds +-10# or so.
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Old 08-27-2012, 12:57 PM   #48
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Originally Posted by Thomas G. View Post
I'm sitting here waiting for Carol's simple explanation of the dynamics of trailer sway. In 25 words or less.
I luv a challege! so here it is. Note CG of trailer was off to the side but look what happens as it is moved.
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Old 08-27-2012, 01:54 PM   #49
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Found this on another forum, don't think it hits the 25 words or less but.... makes sense. Forward center of gravity creates a measure of force counter to the lateral force that would be inducing the sway.

Quote:
For simplicity,
One axle trailer. Let's pretend one wheel too. The trailer is just a
beam with a hitch at one end and a wheel mounted somehow near the
center of the beam.
The tow hitch is stationary.
The trailer is on a short conveyer belt running under it to mimic road
travel.
We are looking down form above with the top of our head toward the
front of the trailer.

The trailer sways to the right.
We instantaneously remove the hitch pin.

If the CG of the trailer is behind the wheel, the wheel acts as a
pivot, and the trailer tries to rotate counter clockwise.

If the CG of the trailer is in front of the wheel, the wheel acts as a
pivot, and the trailer tries to rotate clockwise.

Counter-clockwise increases the sway, but clockwise opposes the sway.
Liked the bath article (not going to do the math) my big take aways were: anti-sway becomes less effective at higher speeds, increased TV mass does not reduce sway by much and center loaded is better than edge loading.

The other big one was the distance between rear axle and trailer hitch determines the leverage the trailer can apply to TV when it sways, a much bigger factor than TV mass. This tells me that a small suv or short bed truck with rear wheels closer to hitch might be an advantage over a long bed truck or car with a long trunk that extends well past the rear axle. And explains why 5th wheels have an advantage in handling sway.

From the posts here and in other forums it seems the safest and most reliable way to get a swaying trailer under control is to manually apply trailer brakes. Probably a good manuver to practice until hitting that control does not involve searching for it in an emergency. The way I always search for the flashlight when the power goes out. Sigh
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Old 08-28-2012, 12:50 AM   #50
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Here are some photos to contemplate. I used to see these in the 60s being pulled by Cadillacs and Lincolns. I don't believe they swayed much. The tongue is hinged up and down so the only weight on the ball is the weight of the tongue.
Attached Thumbnails
1-IMG_1510.JPG   1-IMG_1524.JPG  

1-IMG_1525.JPG  
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Old 08-28-2012, 02:01 AM   #51
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funny you should bring up horse trailers - that type was indeed used by those with the big bucks. I actually learned to tow with a horse trailer and my first tow was only a few weeks after I obtained my drivers license. I wish it had been this type of trailer. The one I towed with did not have the forward axle or electric brakes just surge brakes so you had little choose about whether or not you used the tow vehicles brakes if the trailer started to sway - one hasnt really lived until they a towing an old horse trailer of the 70's vintage and had 4 or 6 horses in back decide to start up a dance party. If anyone asks me today how I know when my trailer isnt loaded correctly and how I know it could start to sway - trust me I know the feeling. Looking back at those times makes me realize how unsafe some of the practises and equipment we used really were but it sure made some memorable occasions ;-))
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Old 08-28-2012, 05:12 AM   #52
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I think simple explanations of the reasons for trailer sway, or simple answers to 'prevent' trailer sway, demonstrate that the person hasn't understood the question.

Each combination of tow vehicle/trailer/loading condition is different and while there are some good rules of thumb, like sufficient tongue weight, there are no simple answers.

That video above is a good example of what appears to be a fairly stable trailer that is only stable up to a certain amount of 'slaloming' at speed. Driven moderately, I bet the owner could tell of thousands of miles of safe towing.
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Old 08-28-2012, 10:35 AM   #53
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Originally Posted by Andrew Gibbens View Post
I think simple explanations of the reasons for trailer sway, or simple answers to 'prevent' trailer sway, demonstrate that the person hasn't understood the question.

Each combination of tow vehicle/trailer/loading condition is different and while there are some good rules of thumb, like sufficient tongue weight, there are no simple answers.....
True every combination of equipment and load is pretty unique, that said guidelines or rules of thumb apply the 80/20 rule. Follow them and 80% will get good results, the other 20% need to be smart enough to stop the trailer and figure out why the darn thing feels squirrely and do something about it.

The general guidelines also provide a "baseline" that one can work from to track down the unique exception. Total weight ok, toungue weight good, trailer is towing level, this eliminates the basics and if the trailer then seems prone to sway or poor tracking you know you need to dig deeper to find the cause. Maybe it is tires or suspension, could be over loaded on one side but you are working from a "known" good starting point to track down the problem.

If the problem is your trying to flee and elude a police car while towing a trailer well..... consider it an experiment in stupidity. One where the lab rats are not going to enjoy the results.
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Old 08-28-2012, 04:28 PM   #54
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Here is a link that might help the OP HowStuffWorks "How Tongue Weight Works"









As always and as most are trying to say, follow your manufactures guidelines found in your Vehicle manual. Good Luck!
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Old 08-28-2012, 06:27 PM   #55
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RE: Dissertations
European vehicles and accessories are all heavily regulated and inspected on a rgular basis. In Germany you can't just built a trailer hitch, it has to be one approved for your vehicle and then inspected , for a particular use, after installation .And trucks and vehicles with trailers driving slow in Europe has always been the case, up to the point of it's a major cause of accidents. Imaging Gunther in his Mercedes cruising at about 140 mph and a truck going 45 mph pulls out into his lane to pass one going 43 mph. For this reason fewer and fewer Autobahns are marked for unlimited speed.
AND (Big and) ST (trailer use only) tires are rated for a maximum speed of 65MPH, so those faster speed limits usually aren't for those pulling a SCAMP or a Boler down the hiway. In CA, the speed limit for trailers is 55 MPH. Period.
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Old 08-28-2012, 06:57 PM   #56
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I was very impressed on with German autobahn drivers, they seemed to be seriously polite, similar to their personal relationships. I agree they are certainly a country of regulations.
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