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Old 10-18-2007, 07:39 PM   #1
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Does the Equalizer shift weight to trailer axles?

A salesman told me the Equalizer will shift almost all the tongue weight to the trailer axles. He said only about 100 lbs. of the 720 lb. tongue weight on a Safari 25' FB will go to the TV and the rest goes to the trailer.

I can understand how the friction bars on the Equalizer can combat sway, but this weight shifting is beyond my understanding. I can understand how a WD tow receiver on the truck side shifts weight to the frame and thus to both TV axles. Maybe the Equalizer is a WD device as well as an anti-sway device. Perhaps the salesman is a shapeshifter (fortunately the full moon wasn't out).

Is this true (the weight shifting, not the salesman's proclivities)? If it is, does the tongue weight (i.e., the 600 or so lbs.) count against the cargo capacity of the trailer? I would guess that would count those lbs. twice.

Maybe I should've stayed in the engineering program in college, but it interferred with drinking; liberal arts was my solution, but it doesn't help now. I don't think I understand tongue weight and what it all means, and to those of you who do, I think that must be obvious. I do understand beer, however.

Thanks in advance for an education.
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Old 10-18-2007, 08:02 PM   #2
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'nother liberal arts...(well the drinking part anyway) major here Don't buy the salesman's BS. I am no engineering marvel, but from my understanding with the Equalizer hitch is that it helps to transfers some of the direct load back to the trailer and to the front wheels of the tow vehicle. I have an Equalizer that I use when I tow my AS with my wife's F150 it takes the truck from a 6" down position up to level. As far as I know you still have to have the proper ratings as far as capacity on the truck. And I don't think using an equalizing hitch is going to change the load capacities on the trailer, it may up the measurable weights on the axles a bit, but if you are within your weight ranges it should be a non issue.

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Old 10-18-2007, 08:03 PM   #3
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Quote:
Originally Posted by CrawfordGene
A salesman told me the Equalizer will shift almost all the tongue weight to the trailer axles. He said only about 100 lbs. of the 720 lb. tongue weight on a Safari 25' FB will go to the TV and the rest goes to the trailer.

\\ MASSIVE SNIP //

Thanks in advance for an education.
try the little search box on the top right above.

just sayin'

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Old 10-18-2007, 08:18 PM   #4
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WD bars impart a moment about the hitch ball shifting some of the original tongue weight to the front wheels of the tow vehicle. In the process they also increase the weight on the rear axle of the trailer while reducing the weight on the front axle of the trailer. I would guess Airstream Co, has presumed that all people who pull larger Airstreams will be using WD hitches and have designed the axles to take it. If you put too much torque on the bars you will shift too much weight and overload the axles. I did finish my BS degree in mechanical engineering but these calculations are part of the Statics program which is a freshman course. Also taught as part of first chapter of physics as part of the 1st law of physics " for a static body for every force there is a equal and counter acting force. Simply write a moment formula around the ball of the hitch and draw a free body diagram of the trailer and the spring bars and hitch ball acting on it as well as the wheels and the weight of the trailer. It is a piece of cake. Equalizer hitches however are just high price frictional dampers by comparison to the self centering nature of the Reese twin cam hitch. The Hensley is alot harder to see how it works at first glance but is a very interesting four bar linkage.
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Old 10-18-2007, 08:27 PM   #5
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Quote:
Originally Posted by dwightdi
Simply write a moment formula around the ball of the hitch and draw a free body diagram of the trailer and the spring bars and hitch ball acting on it as well as the wheels and the weight of the trailer. It is a piece of cake.
I was going to say that...............
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Old 10-18-2007, 08:31 PM   #6
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Nick Crowhurst has developed some very precise formulas (yes, free body diagrams) for calculating the amount of weight transfer from the rear axle, to the front axle and trailer axle. You need to know several dimensions, especially the distance from the trailer axle to the hitch, and from the hitch to the rear axle, and the wheelbase of the vehicle. You can find his formulas by using the search function.

But to simplify the issue, to restore the front of the tow vehicle to it's original attitude, most trailer/tow vehicle combinations will transfer about 50 percent of the added load off the rear axle. Of that 50%, about one third of that goes to the trailer axle, and two thirds goes to the front axle of the tow vehicle. True for either an Equalizer, Reese, or any spring bar WD hitch.
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Old 10-18-2007, 09:37 PM   #7
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Since my brief excursion into college physics was 49 years ago, and I learned very little, if anything, I'm quite lost with "free body diagrams", et al. I do remember something about "moment arms", but I just remember the words. I guess Mark's answer was one third of 50% goes to the trailer axle. So of 720 lbs., that's 120 lbs. The front axle of the TV gets 240 lbs. So does the rear axle of the TV get the other 360?

I stand ready to answers questions about history and law and beer.

All this about the payload of my truck and whether I am within safe limits and 120 lbs off the truck may just about do that.
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Old 10-18-2007, 10:54 PM   #8
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Quote:
Originally Posted by CrawfordGene
. . So of 720 lbs., that's 120 lbs. The front axle of the TV gets 240 lbs. So does the rear axle of the TV get the other 360?
It's a little more involved than that. I'll use the dimensions of my Tahoe/Tradewind to illustrate.

Tongue weight - 720 lbs

Without a WD hitch, the 720 lbs actually adds 1070 lbs to the rear axle, and subtracts 350 lbs from the front axle. The 'tetter-totter' effect at work.

If you set the bars so the front end returns to it's original height, the bars have the effect of removing 520 lbs from the rear axle. With the geometry of my combination, 350 lbs gets added to the front axle, and 170 lbs transferred to the trailer axle.

So for the weight in question (1070 lbs), half is removed (520 lbs), with two thirds (350 lbs) going forward and one third (170 lbs) to the trailer.

The equations are set up to assume the front returns to it's original load. Of course you can tighten the bars even more and transfer more of the weight off the rear axle, but the two-thirds, one-third ratio stays fairly constant as it is a function of the wheelbase and hitch to axle measurements.
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Old 10-19-2007, 12:27 AM   #9
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Thanks Mark. I feel like my clients must have felt when I tried to explain their legal issues to them—they'd get that glazed eye look. I have an '07 Tundra and am interested in a 25' Safari. How that TV and trailer would differ from yours, I don't know. I have read books on RV's and many threads, but I seem to lack the tongue weight gene.

Given your example, does that mean your truck carries 870 lbs with a 730 tongue wt.?
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Old 10-19-2007, 12:41 AM   #10
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Quote:
Originally Posted by CrawfordGene
...Is this true (the weight shifting, not the salesman's proclivities)? If it is, does the tongue weight (i.e., the 600 or so lbs.) count against the cargo capacity of the trailer?...
i agree with the others who have explained that the...

steering axle is reloaded and the drive axle unloaded and the trailer axle load increased....

but the mass is STILL at the tongue and part of the trailer

so YES it counts against cargo capacity for the trailer and no you cannot add more beer...

let me carry d'beer for ya

but NO it isn't included twice (tv and trailer)....

while the hitch (apparatus) weight IS counted against tv payload and gcwr...

after proplerly tightened up...

as i understand it....

cheers
2air'

and in marks' example the truck 'carries' approx 550lbs and the trailer axles 170 of the original 720....

nothing actually weights 1070 lbs, that is the force generated at the rear axle without w/d bars...

since the original tongue mass is behind this axle the 720 gets multipled by a factor related to this distance....

the same actual 720 lbs on a really long overhang vehicle would create >1070lbs at the drive axle,

while on a really short overhang the figure would be <1070...

while the front axle load is REDUCED in each example again based on the teeter totter pivot points....

so the basic purpose of the w/d bars is to RELOAD the front (steering axle) while reducing the exaggerated load on the rear (drive axle)...

the math IS really is helpful, but taking the entire set up to a scale and reading what actually happens is most useful...

http://www.airforums.com/forums/f238...ers-17984.html

is one thread with this info, there are others....

cheers
2air'
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Old 10-19-2007, 01:19 AM   #11
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One Equalizer adjusted to level said tow vehicle with trailer and tow vehicle loaded with nescessary gear and beer for the trip to adhere to tow vehicles given load capacity.....a....just make the damn thing level and yer fine.
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Old 10-19-2007, 03:20 AM   #12
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It seems I'm always a day late,I just finished reading Your CAT adventures from last yr. GOOD STUFF. I did get a '77 27ft Overlander. I have resolved my 21 1/2" ball height issue,with a 2"Blue OX drop" With a solid Reese Drawbar Im at 19" unloaded,with the trailer level the Coupler is at 18". I'm very lucky Where I retired from has an 80' state certified scale that I can use for NOTHING, U cant beat the price.The hitch I used to bring the trailer home came with the trailer(adjustable ReeseDrawbar With 1400 lb bars) I did notice a lot of bounce up and down on the bridges on I 74 Im gonna change to the 1000# bars(I now have both) and the old straight line and see what happens. Thanks for all the good data.
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Old 10-19-2007, 03:27 AM   #13
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Thanks for all the data I just finished reading your CAT adventures from last yr.GOOD STUFF. I did make a purchase '77 27ft Overlander.I have resolved my hitch height issues and now on to the CAT adventrures.Let U know what I find.
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Old 10-19-2007, 03:31 AM   #14
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Me thinks its time for Some shut eye .^^^^^doing double posts cause the first one disappeared on me!Then reappeard HMMMM wonder what thats all about?
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