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Old 04-10-2015, 01:31 PM   #21
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Originally Posted by OldCoot View Post
Defies logic!
Maybe this helps:

Truck without air in rear air bags:

Click image for larger version

Name:	IMG_1194.JPG
Views:	88
Size:	227.8 KB
ID:	73797

Truck with air in rear air bags:

Click image for larger version

Name:	IMG_1195.JPG
Views:	102
Size:	221.7 KB
ID:	73798

The front wheel acts as a pivot point, so the area over the front fender (where we take the measurements while setting up a WDH) do not change.
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Old 04-10-2015, 01:42 PM   #22
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Originally Posted by MtnGuy View Post
Maybe this helps:
The front wheel acts as a pivot point, so the area over the front fender (where we take the measurements while setting up a WDH) do not change.
Is your toy truck hooked to wdh?

Whatever you want to believe. Good bye!
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Old 04-10-2015, 01:43 PM   #23
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Quote:
Originally Posted by MtnGuy View Post
Maybe this helps:

Truck without air in rear air bags:

Attachment 73797

Truck with air in rear air bags:

Attachment 73798

The front wheel acts as a pivot point, so the area over the front fender (where we take the measurements while setting up a WDH) do not change.
In my opinion you are not taking into account suspension sag due to the added TW which will affect the area above the wheel. You are correct about the axle being a pivot point (fulcrum)

A statics equation states that weight no matter where it is applied (either forward or behind a fulcrum) acts on the body as a whole. This equation is known as M = F(w) X Distance. Moment equals force (or weight) times the distance. Since the double fulcrum (both axles on a vehicle) is not a solid state fulcrum (the axle due to springs/shocks) the force is transferred across the fulcrum but decreased the further it goes form the place the force is applied. So since the weight is the force and it is applied to the rear of the vehicle that force is transferred across the non-solid state fulcrums and it is absorbed by the suspension resulting in sag.

If your truck in the picture above had suspension and a force applied to the rear of it the picture would not look the same, it would look similar but not the same.
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Old 04-10-2015, 01:55 PM   #24
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Quote:
Originally Posted by MtnGuy View Post
Maybe this helps:

Truck without air in rear air bags:

Attachment 73797

Truck with air in rear air bags:

Attachment 73798

The front wheel acts as a pivot point, so the area over the front fender (where we take the measurements while setting up a WDH) do not change.
That's one really REALLY big ruler. Nice truck btw.
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Old 04-10-2015, 02:01 PM   #25
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In my opinion you are not taking into account suspension sag due to the added TW which will affect the area above the wheel. You are correct about the axle being a pivot point (fulcrum)

A statics equation states that weight no matter where it is applied (either forward or behind a fulcrum) acts on the body as a whole. This equation is known as M = F(w) X Distance. Moment equals force (or weight) times the distance. Since the double fulcrum (both axles on a vehicle) is not a solid state fulcrum (the axle due to springs/shocks) the force is transferred across the fulcrum but decreased the further it goes form the place the force is applied. So since the weight is the force and it is applied to the rear of the vehicle that force is transferred across the non-solid state fulcrums and it is absorbed by the suspension resulting in sag.

If your truck in the picture above had suspension and a force applied to the rear of it the picture would not look the same, it would look similar but not the same.
Can you believe I actually understand what you are posting ?? Great explanation.

As you add tongue weight, the back of the truck goes down, and the front goes up. A WDH pulls up on the rear of the truck, putting the lost weight back on the front wheels.

What I have been saying from the start of this discussion, is that rear air bags do little to distribute weight to the front axle.......whether used with or without a WDH. The only weight that it could move forward is the slim "sliver" of truck that is directly over the rear axle before adding air and then after adding air.....because the rear of the truck comes up, there would have to be a tiny center of gravity change over the rear wheels.

In the case of my toy truck: I was trying to make a point as the rear of the truck goes up, the front bumper goes down, but the area directly above the front wheel (front fulcrum) stays the same.
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Old 04-10-2015, 02:15 PM   #26
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Can you believe I actually understand what you are posting ?? Great explanation.

As you add tongue weight, the back of the truck goes down, and the front goes up. A WDH pulls up on the rear of the truck, putting the lost weight back on the front wheels.

What I have been saying from the start of this discussion, is that rear air bags do little to distribute weight to the front axle.......whether used with or without a WDH. The only weight that it could move forward is the slim "sliver" of truck that is directly over the rear axle before adding air and then after adding air.....because the rear of the truck comes up, there would have to be a tiny center of gravity change over the rear wheels.

In the case of my toy truck: I was trying to make a point as the rear of the truck goes up, the front bumper goes down, but the area directly above the front wheel (front fulcrum) stays the same.
I agree that air bags alone do little to distribute weight to the front, this action is actually a secondary action or an unitended consequence of leveling a vehicle (front to back-not redistributing weight) and in that we are in agreement. But I will respectfully disagree that the area over the front wheel stays the same, I will say that it does in fact change. It has to change because it can be seen visually in most cases but it may be a small change due to the way suspension systems compensate for weight. This area will also be dependent on what type of suspension and the age of the suspension. I will agree in solid state fulcrums this area remains constant, which can be seen in your picture.

From a theoretical sense with a perfectly working suspension in a controlled environment I would agree mathematically that the area would be the same, but in real world application with suspensions being worn and used over time this area will change, and it will actually change each towing trip unless the exact same conditions and loading are identical each trip as it was to time of initial set up.
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Old 04-10-2015, 02:27 PM   #27
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I agree that air bags alone do little to distribute weight to the front, this action is actually a secondary action or an unitended consequence of leveling a vehicle (front to back-not redistributing weight) and in that we are in agreement. But I will respectfully disagree that the area over the front wheel stays the same, I will say that it does in fact change. It has to change because it can be seen visually in most cases but it may be a small change due to the way suspension systems compensate for weight. This area will also be dependent on what type of suspension and the age of the suspension. I will agree in solid state fulcrums this area remains constant, which can be seen in your picture.

From a theoretical sense with a perfectly working suspension in a controlled environment I would agree mathematically that the area would be the same, but in real world application with suspensions being worn and used over time this area will change, and it will actually change each towing trip unless the exact same conditions and loading are identical each trip as it was to time of initial set up.
I think we are in agreement !!
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Old 04-10-2015, 02:29 PM   #28
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Old 04-10-2015, 02:35 PM   #29
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I think we are in agreement !!
When I first read the thread I thought you were saying that a WDH and then adding bags does nothing to transfer weight to the front, but yes we are in agreement that you should use a WDH to transfer weight to the front then you should use bags to level (front to back, this is not for true weight distribution purposes) the entire rig out. Correct?
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Old 04-10-2015, 02:37 PM   #30
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I simply suggested the air bags to stiffen the rear end. These half ton trucks mine very much included, are soft in the rear end. After I get my wdh set I add air to stiffen the rear springs a bit to make the ride better and less porposing as you hit dips, bridges, etc... After all in a perfect world, don't we want the TV and TT to ride as close to level as we can, and so they travel more as one unit going down the highway.. If I'm wrong here I'm sorry and won't add any more of my 2 cents... 😝
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