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Old 08-24-2012, 09:26 AM   #1
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Is this true : WDH does change the loads carried by ALL three axles !

Just came across the following :

'A WD system DOES CHANGE the loads carried by ALL THREE AXLES, reducing the rear axle load of TV while increasing the loads carried by RV's axle(s) and front TV's axle'.

Any WDH system WILL transfer some of the weight from the rear of the tow vehicle to the trailer axle, and how much goes to front axle vs trailer axle will depend on the ratio of the ball-to-axle distances...

Picture the extreme of the adjustment being set so high that the rear wheels are off the ground (like the old advertisement) -- The trailer axle is clearly supporting more than the trailer!

You can crank up those spring bars enough to counteract the nose-up tilt of the tug, or less, or more (yes, CD Smith, we know this is bad), or whatever you want until something breaks or the rear wheels come off the ground - even if there was zero tongue weight to start with. The amount of load it is able to transfer is not limited or affected by the trailer's actual weight distribution.

The WD system changes the distribution of the load, but doesn't move any mass anywhere, and therefore it can't (nor can any technology known to science) make the weight happen anywhere other than where the mass is. The tongue weight stays where it always was, on the hitch ball. It's just a matter of which tires support the whole mess.'

Is above statement 100% true and correct ?
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Old 08-24-2012, 09:45 AM   #2
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The best way to verify this is to take the rig to a scale. Weigh each axle independently. On both the trailer and TV. Then release the tension on the WD bars and weigh everything again.
You will get every opinion under the sun on this subject. So why not just go to the scale? And see for yourself.
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Old 08-24-2012, 10:17 AM   #3
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Originally Posted by Timofeevich View Post
Just came across the following :

'A WD system DOES CHANGE the loads carried by ALL THREE AXLES, reducing the rear axle load of TV while increasing the loads carried by RV's axle(s) and front TV's axle'.

Any WDH system WILL transfer some of the weight from the rear of the tow vehicle to the trailer axle, and how much goes to front axle vs trailer axle will depend on the ratio of the ball-to-axle distances...

Picture the extreme of the adjustment being set so high that the rear wheels are off the ground (like the old advertisement) -- The trailer axle is clearly supporting more than the trailer!

You can crank up those spring bars enough to counteract the nose-up tilt of the tug, or less, or more (yes, CD Smith, we know this is bad), or whatever you want until something breaks or the rear wheels come off the ground - even if there was zero tongue weight to start with. The amount of load it is able to transfer is not limited or affected by the trailer's actual weight distribution.

The WD system changes the distribution of the load, but doesn't move any mass anywhere, and therefore it can't (nor can any technology known to science) make the weight happen anywhere other than where the mass is. The tongue weight stays where it always was, on the hitch ball. It's just a matter of which tires support the whole mess.'

Is above statement 100% true and correct ?
My opinion is that it is basically describing what happens. One problem comes up in a lot of these discussions and I think some of it is present in this above explanation. That problem is the interchangeable or incorrect use of the words weight, mass and force. If one wants to make a statement like this and have it be totally correct, the term weight should be left entirely out of it. It should be a discussion of forces only. Weight is a term used to describe the static force generated by a stationary mass in a vertical direction due the the apparent acceleration of gravity. Take for instance the statement that the tongue weight stays where it is. The force that is pushing down on the tongue is technically not weight. It is a force resulting from mass that is not directly over the trailer wheels acting at the end of a long lever (the trailer frame).
As long as one sticks with scientifically defined terms and uses methods taught in any basic statics course it is a simple process to analyze the forces present at any given point and the changes in forces if the position of any part of the system is changed. These forces can also be calculated in a system subject to external changing forces, such as a tow vehicle trailer combination traveling on the highway. However it requires a higher level of mathematics.

Therefor I take a careful look at any analysis of forces that uses the word weight.

Ken
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Old 08-24-2012, 11:34 AM   #4
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It's a "loaded" question for sure and I like what TG and Ken say.

Simplest look at it, the weight distribution hitch distributes some of the rear axle weight to the front axle and the trailer. If you need to know exact numbers, weigh each axle. In theory it would be 1/3 of the added rear axle weight to the front axle, 1/3 left on the rear axle, and 1/3 to the trailer axle(s).

But transferring weight with these hitches can be increasingly difficult on tow vehicles with stiff suspensions and long wheelbases. Again, only a scale will be accurate.

doug k
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Old 08-24-2012, 11:52 AM   #5
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The weight, force, mass, whatever you want to call it on the ball does not ch,ange, no matter where the force is redistributed. You can't lessen or increase that, you can only redistribute the force. So, if you have a receiver with a maximum capacity of 500 pounds, using a weight distributing setup will not remove any of the 600 pounds or so of weight from the receiver.
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Old 08-24-2012, 11:59 AM   #6
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Quote:
Originally Posted by Timofeevich View Post
Just came across the following :

'A WD system DOES CHANGE the loads carried by ALL THREE AXLES, reducing the rear axle load of TV while increasing the loads carried by RV's axle(s) and front TV's axle'.

Any WDH system WILL transfer some of the weight from the rear of the tow vehicle to the trailer axle, and how much goes to front axle vs trailer axle will depend on the ratio of the ball-to-axle distances...

Picture the extreme of the adjustment being set so high that the rear wheels are off the ground (like the old advertisement) -- The trailer axle is clearly supporting more than the trailer!

You can crank up those spring bars enough to counteract the nose-up tilt of the tug, or less, or more (yes, CD Smith, we know this is bad), or whatever you want until something breaks or the rear wheels come off the ground - even if there was zero tongue weight to start with. The amount of load it is able to transfer is not limited or affected by the trailer's actual weight distribution.

The WD system changes the distribution of the load, but doesn't move any mass anywhere, and therefore it can't (nor can any technology known to science) make the weight happen anywhere other than where the mass is. The tongue weight stays where it always was, on the hitch ball. It's just a matter of which tires support the whole mess.'

Is above statement 100% true and correct ?
When using a proper rated load equalizing hitch, properly installed, AND properly adjusted, two thirds of the trailer tongue weight will go to the tow vehicle and one third will go back to the trailer axle/axles.

Of the two thirds that go to the tow vehicle, one fourth of that should go to each tire, but again, if everything is correct.

Andy
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Old 08-24-2012, 12:36 PM   #7
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Originally Posted by overlander63 View Post
The weight, force, mass, whatever you want to call it on the ball does not ch,ange, no matter where the force is redistributed. You can't lessen or increase that, you can only redistribute the force. So, if you have a receiver with a maximum capacity of 500 pounds, using a weight distributing setup will not remove any of the 600 pounds or so of weight from the receiver.
True, but does it matter. If the receiver and its mounting are strong enough, and it is the rear axle load you are concerned with, some of the weight on the rear axle is no longer there. In fact you can lighten the rear axle with a weight distribution hitch so that the vehicle is dangerous, not enough traction to control the trailer.

doug k
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Old 08-24-2012, 03:35 PM   #8
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Originally Posted by Inland RV Center, In View Post
When using a proper rated load equalizing hitch, properly installed, AND properly adjusted, two thirds of the trailer tongue weight will go to the tow vehicle and one third will go back to the trailer axle/axles.

Of the two thirds that go to the tow vehicle, one fourth of that should go to each tire, but again, if everything is correct.

Andy

Andy,

So if I read you correctly an example might be-Starting with 900 lbs tongue weight (i.e. on the ball) without WD bars installed or adjusted. After proper installation of bars and adjustment results in 600 on the ball, with 150 lbs on each of the 4 corners of the TV. 300 lbs then go back to the trailer axles.
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Old 08-24-2012, 05:51 PM   #9
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So if I read you correctly an example might be-Starting with 900 lbs tongue weight (i.e. on the ball) without WD bars installed or adjusted. After proper installation of bars and adjustment results in 600 on the ball, with 150 lbs on each of the 4 corners of the TV. 300 lbs then go back to the trailer axles.
NO.
900 pounds is on the ball, no matter if you move 1 pound or 900 pounds to the front axle. Period. The amount of weight on the ball DOES NOT CHANGE.
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Old 08-24-2012, 06:42 PM   #10
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Doesn't matter what's on the ball if the receiver and it's attachments are stout enough to hold it. What matters is that the load on the rear suspension and axle is reduced.

For example, Can-Am RV uses this principle to take a small, lightweight but good handling tow vehicle, reinforce the hitch, install an appropriate weight distribution hitch, better tires and good brake controller and produce a successful tow vehicle for his customers. Not all agree with this approach but the customers are quite pleased.

Some mfg's raise hitch weight limits on their trucks with weight distribution even though the hitch remains the same.

doug k
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Old 08-24-2012, 10:57 PM   #11
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NO.
900 pounds is on the ball, no matter if you move 1 pound or 900 pounds to the front axle. Period. The amount of weight on the ball DOES NOT CHANGE.

I see no reason to be rude and shout. My post was directed at another person asking them to clarify their statement, it had nothing to do with my understanding or lack thereof of the orginal question. I realize this is a public forum and anyone can comment on any post, but this seems out of line.
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Old 08-24-2012, 11:18 PM   #12
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It's not quite as simple as the 1/3 rule... but that's a reasonable approximation for most designs. What you need to look at is the levered force you are creating... and like any lever, the length from the fulcrum that the force is applied. For example, if you had a 100' long trailer with the wheels 80' back, the weight transferred to the rear axles would be minimal because the lever is so long (just using extreme figures to make a point).

Likewise going the other way, if your receiver is very close to your rear axle, like many SUV's, you can run into making the rear end too light because of how close the force is applied in relation to the rear axle.

The first statement is 100% true... not 100% of the science of it, but its points are true. WD is sort of like wheelbarrow handles for your tow vehicle. When you lift up on a wheelbarrow, it doesn't get lighter... part of the load is now in your hands, the other part is transferred to the wheel. With spring bars, the trailer frame becomes the arms and the bars are the handles. The result is the spring bars are trying to lift the rear of the TV... the 'feet' of the equation are the tires on the trailer... which just happen to be a ways back (which is why they get less force than the tow vehicle).
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Old 08-25-2012, 09:08 AM   #13
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Andy,

So if I read you correctly an example might be-Starting with 900 lbs tongue weight (i.e. on the ball) without WD bars installed or adjusted. After proper installation of bars and adjustment results in 600 on the ball, with 150 lbs on each of the 4 corners of the TV. 300 lbs then go back to the trailer axles.
Absolutely correct.

Scales can easily document those weight changes.

The weight on the ball can actually decrease to zero.

Weight tests confirm that.

An opinion, is just that, with no documentation attached.

Many many years ago, Caravanner Insurance and I did tons of tests proving what did and did not happen with load equalizing hitches.

We also proved over 85 percent of the time, what caused "loss of control" accidents, yet some say that cannot be done.

The laws of Physics still applies, no matter what an opinion may be.

Andy
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Old 08-25-2012, 09:43 AM   #14
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Okay, I am going to try this one more time, then I am going to give up and let people believe what they want. Moving the force on the ball does not change the weight on the ball. That is like getting an elephant to stand on one foot, to make him weigh 75% less.
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