Weight distributing hitch math?

westend wrote:
Move blue arrow to the right in your depiction, Francesca. As Skip said, "weight is accounted for once". Applying force with the WDH does NOT increase your truck's payload rating. In fact using a WDH decreases the trucks available payload by the weight of the hitch.

I'm not asking about weight/payload capacity- I'm asking about the forces used to move the weight around. Can they be measured, and if so, how?

My main area of interest is the trailer frame, at that point where the red arrow is. Isn't that some sort of stress point? If so, how many "pounds of stress" is it under?

Move blue arrow to the right in your depiction, Francesca. As Skip said, "weight is accounted for once". Applying force with the WDH does NOT increase your truck's payload rating. In fact using a WDH decreases the trucks available payload by the weight of the hitch.

Francesca Knowles wrote:

Ron Gratz wrote:

Francesca Knowles wrote:
Is the "force" required to shift the weight measurable, and if so how much is required in the above example?

Francesca, are you referring to the upward force which is applied to the rear ends of the weight distribution bars?

Ron

I think so- I'm not exactly sure WHAT force I'm referring to. My very dim understanding of the way levers work is that there has to be some force exerted somewhere in order to shift the weight.

Thing is, I keep looking at pictures, and it appears to me that the bars/chains must be pulling on the trailer tongue at the connection point, pushing it down against the fulcrum provided by the ball. I s'pose that's wrong, but it's the only logic my simple mind can come up with that explains why the front end of the tug gets "lighter".

Per my earlier question- found a picture that I hope clarifies what I'd really like to know, which is:

Can the stress on the trailer's tongue at the "red arrow" point be expressed/predicted in terms of pounds?

Ron Gratz wrote:



With WD applied, the amount of load transferred to the TT's axles does not need to be included in the payload.

Ron

Come on man...from a guy who takes book numbers to the extreme and posts thesis papers for explanations...you state this as a matter of fact? It is not.

While it agrees with my previous statement, this is not how any weights are EVER calculated. Its fine if a scale is used and actual transferred weights are learned, but they are not to be used to change any weight calculations.

All calculations are done without WDH.

Ron Gratz wrote:

Mvander wrote:
Im a simple guy so ill ask a simple question. Truck has 4 wheels on scale with tt on the ball with a weight of 6000# trailer is not on scale.

Now you snapup the wd bars. Does the truck now weigh less? If it does would it not have more available payload?

Yes, it would. Here's an example from four days ago.

Thank-you for clarifying Ron. I always thought this to be the case but your example re-inforces it in my mind.

Without the rear wheels that must have been an interesting ride, the Toronado was no small car.

It seems mystical, until you realize all they did was run a couple of steel beams i.e. torsion bars, between the frames. If they only wanted to go straight they could have welded the frames together.

Adding the chains or other such mechanisms so the unit can turn is a nice piece of engineering.

Ain’t Physics wonderful, at least that is my professor said. :B

Mvander wrote:
Im a simple guy so ill ask a simple question. Truck has 4 wheels on scale with tt on the ball with a weight of 6000# trailer is not on scale.

Now you snapup the wd bars. Does the truck now weigh less? If it does would it not have more available payload?

Yes, it would. Here's an example from four days ago.

TV weight was 2100+5200 = 7300# with TT hitched and no WD applied
TV weight was 2480+4660 = 7140# with TT hitched and WD applied
With WD applied, the TV had an extra 160# available for payload

The load on the TT's axles increased by 8280-8140 = 140#

The discrepancy of 160# versus 140# can be attributed to scale accuracy.

Ron

Truck only:
Front:2660
Rear:3380
Gross:6040

Truck and Trailer Bars Hooked:
Front:2480
Rear:4660
Trailer:8280
Gross:15420

Truck and Trailer Bars Unhooked:
Front:2100
Rear:5200
Trailer:8140
Gross:15440

Ivylog wrote:
I remember Reece going around in the 60s with a Airstream and a FWD Toronado that they took the rear tires off to demonstrate their new WD and friction sway products. While not the picture I hoped to find, I'm pretty sure the rear axle has gain a BUNCH of CCC/RGVW.

Not an Airstream -- but a Toronado with no rear wheels. Also a link to a Popular Mechanics article.



Popular Mechanics July 1969 page 134

Ron

Im a simple guy so ill ask a simple question. Truck has 4 wheels on scale with tt on the ball with a weight of 6000# trailer is not on scale.

Now you snapup the wd bars. Does the truck now weigh less? If it does would it not have more available payload?

Ron Gratz wrote:

Francesca Knowles wrote:
Is the "force" required to shift the weight measurable, and if so how much is required in the above example?

Francesca, are you referring to the upward force which is applied to the rear ends of the weight distribution bars?

Ron

I think so- I'm not exactly sure WHAT force I'm referring to. My very dim understanding of the way levers work is that there has to be some force exerted somewhere in order to shift the weight.

Thing is, I keep looking at pictures, and it appears to me that the bars/chains must be pulling on the trailer tongue at the connection point, pushing it down against the fulcrum provided by the ball. I s'pose that's wrong, but it's the only logic my simple mind can come up with that explains why the front end of the tug gets "lighter".