Jerry9n
SE Michigan
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Joined: 10/28/2008
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Sorry but due to some physical constraints I can't take any measurements for several weeks. If you PM me then, I'll make measurements.
Jerry9n
2009 23' Cikira Escape EXP
2006 Ford Expedition
Reese Pro Series SC
Tekonsha Primus IQ
HTT Mods
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LarryJM
NoVa
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Joined: 11/09/2007
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BarneyS wrote: He simply asked how much pressure would occur between the trailer coupler and the ball of the hitch if one were to put a gauge in between those two items. That pressure would INCREASE by quite a bit (1700lbs in the example in the hitch sticky post).
The example you gave is typical of WD use which removes weight from the rear axle but DOES NOT remove weight from the tongue. Tongue weight is tongue weight and does not change. The only way to remove weight from the tongue is to move the trailer axles forward, or load the trailer differently.
Barney
I'm probably totally wrong but that 1700lb pressure figure IMHO is just not possible and I have nothing to based that on but my feeble logic such as it is.
Using my flawed logic the pressure will or I would think decrease if the WDH is taking wt. off the rear axle of the TT and will increase if you load the TV or TT after measuring dead tongue wt. and hooking up the trailer.
Larry
2001 standard box 7.3L E-350 PSD Van with 4.10 rear and 2007 Holiday Rambler Aluma-Lite 8306S Been RV'ing since 1974.
ALL TRAILER MODS>>ETERNABOND INSTALL>>RAINKAP INSTALL
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BarneyS
S.E. Lower Michigan
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Joined: 10/16/2000
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Larry,
The weight off the rear axle has nothing at all to do with the pressure between the ball and the coupler. By the way you said "off the rear axle of the TT" and it does not do that. It takes weight of the rear axle of the truck. I think you may be confusing the rear axle of the truck with the pressure between the BALL and the trailer COUPLER.
When the chains pull DOWN on the trailer tongue, that puts downward pressure on the coupler. Since the coupler rests on the ball, that puts that downward pressure on the ball.
Now, at the same time, the WD bars are pulling UP (with a twisting motion) on the hitch head. The ball is attached to the top of the hitch head. Since the ball rests within the coupler, the ball pushes UP on the coupler. Combine the Down pressure from the coupler, the original tongue weight, and the UP pressure from the ball and you have that huge amount of pressure between the ball and the coupler. That is the question the OP asked.
Notice, in the above description, I have not said a word about the rear axle - now I will. That same UP pressure that is pushing up on the ball via the WD bars/hitch head is also pushing UP on the receiver via the shank. Since the receiver is attached to the frame of the truck, the frame of the truck moves UP and therefor relieves some of the pressure from the rear axle. That twisting motion I mentioned earlier by the WD bars on the hitch head is input into the frame and while relieving the rear axle of part of its' load it also adds that to the front axle.
While all of this is happening, those snap-up brackets back there on the trailer A frame that are pulling DOWN on the A frame are at the same time pulling DOWN on the whole trailer frame. That puts pressure on the trailer axles. The different amounts of pressure (weight) that occurs at each of these places can and has been calculated by Ron Gratz and can be seen by the results from the active weights taken by another member earlier.
Notice, during all of this pressure (weight) moving around, NOTHING has been done to the trailer itself to change the actual tongue weight. It remains what it was before the WD was even hooked up. No firewood, bicycles, or food was added or taken out of the trailer. It is the spring bars acting through the hitch head, trailer frame and truck frame that gives you the different numbers.
Here is a copy/paste of a post that I made some time ago that might help explain it a bit better.
Compare it with a wheelbarrow. The wheelbarrow contains a load of sand (tongue weight) and the bed of the wheelbarrow is the tongue/hitch of the trailer. The handles of the wheelbarrow are the WD bars and your arms are the chains that lift them. The front wheel is the front axle of the truck. The rear supports are the rear axle of the truck and your two feet are the trailer axles. When you lift up on the handles (bars & chains), you transfer the force (weight of sand) from the rear supports (rear axle of truck) to the front wheel (front axle of truck), but at the same time the lifting force of your arms (chains) increases the load on your feet (axles of trailer). At no time during this whole operation did the load in the wheelbarrow change. It is still the same weight of sand (tongue weight) that you started with. The forces that that load of sand created in the wheelbarrow has been moved around but the weight is still the same. The same thing happens with the tongue weight of the travel trailer when you use WD. The actual tongue weight does not change, only the forces that it creates is moved around.
Barney
2004 Sunnybrook 30FKS TT
Hensley "Arrow" 1400# hitch
2002 Ford F250 Super Duty, 7.3L PSD
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Mickeyfan0805
Michigan
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Joined: 11/26/2009
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As we're looking into a potential 1st time purchase, our potential combinations have us more concerned with gross vehicle weight than we are direct hitch load, tow capacity, etc... I can't find anything that speaks directly to the issue of how a WD hitch effects the TT's impact om the weight of the TV.
So, let me ask this of the experts:
I've read this thread, and much of Ron's older thread on this matter. I generally understand the concepts, but am not an engineer and will leave the numbers to the pros. With my read of the concepts, however, it is my understanding that a WD hitch does reduce the load that is being applied to the TV overall.
Using the prime example in the other thread, if the rear axle weigth is reduced by 912, while front axle weight is increased by 612 pounds, this means that the actual vertical load being placed on the TV (and thus the amount of weight you need to consider in staying under the GVWR of the TV) is reduced by 300 pounds.
Is this correct? If so, is there a way to calculate how much of the weight will be taken off of the TV?
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