Tires A physics question of leverage

[orezok]

That was the point as to why your Hulk example was not realistic to the real situation [in which a tractor is centered between its support points - wheel/wheel.] It was not centered for Hulk. Ref 2nd quote above.



Again : Extending support points increases bearing load because the extended support points exert more leverage on the bearing pair.

So the tractor bearing locations got wider in addition to gaining weight :confused2:

 

[Egon]

,,,,,,,,,,,When talking to yourself, try not to contradict.

Well that's where the challange portion comes in. Got to thinking about one side of the axle assembly. Namely, inner race, outer race with the weight being applied between the two. Then the axle with a wheel got added in. With that senario I figured it reasonable that the inner race would be a pivot point for the axle. Using this configuration the whole lot is a lever with a pivot point on the inner race. Can't recall the class of lever though.

Tomorrow may see more revaluations from overnight dreams.

 

[orezok]

Well that's where the challange portion comes in. Got to thinking about one side of the axle assembly. Namely, inner race, outer race with the weight being applied between the two. Then the axle with a wheel got added in. With that senario I figured it reasonable that the inner race would be a pivot point for the axle. Using this configuration the whole lot is a lever with a pivot point on the inner race. Can't recall the class of lever though.

Tomorrow may see more revaluations from overnight dreams.

Since the bearings are mounted in a rigid assembly, the pivot point is actually the other tire. Both bearings should receive the same force, one up one down.

 

[SPYDERLK]

So the tractor bearing locations got wider in addition to gaining weight :confused2:

The tractor still presses down on the wheels with the same force, but if theyre further out that force levers harder on the bearing pairs on each rear axle. A longer lever pushes up/down harder even tho the same force is applied. Think pry bar.

Since the bearings are mounted in a rigid assembly, the pivot point is actually the other tire. Both bearings should receive the same force, one up one down.

No. Each half axle tries to crush its bearing pair - one upward one downward. The bearing being pushed upward [outer] resists a load the same as the downward force on the inner bearing plus the weight of the load being supported by that axle.

 

[orezok]

The tractor still presses down on the wheels with the same force, but if theyre further out that force levers harder on the bearing pairs on each rear axle. A longer lever pushes up/down harder even tho the same force is applied. Think pry bar.

So what you are saying that if you use a longer pry bar, you have to put more force on it to move something. That is what you are saying.

I give up, I think I'll go talk to the dog. She will understand.

 

[SPYDERLK]

So what you are saying that if you use a longer pry bar, you have to put more force on it to move something. That is what you are saying.

I give up, I think I'll go talk to the dog. She will understand.

No. OK.

 

[AxleHub]

Since the bearings are mounted in a rigid assembly, the pivot point is actually the other tire. Both bearings should receive the same force, one up one down.

Orezok, your refusal to recognize deflection makes no sense. "Ridgid" is a relative term based on a continous and unchanged position. But adding length between the outer bearing and the rim is an alteration of the position and as a result side pressure on bearings is created as deflection of the axle changes. I've read your responses to several posters and none of those responses of yours seems to indicate you are understanding the dynamics involved.

I'm done trying to communicate. The other posters are clearly recognizing points and issues you are not.

 

[dmac128]

You really need to know the spacing between each axle bearing pair, and the placement of wheel center wrt the outer bearing to get a good handle on % load increase. ... The proportion increase in bearing load seems it would be much higher -- ~ 50%

Agreed - it's all about geometry. If you look at my calculations, the 4" adjustment increases loads by 23% above 'baseline' and the 4" adjustment + 3" spacer increases loads by 34% above baseline for the assumed geometry. The 9% increase is only for the 4" adj + 3" spacer relative to the 4" adjustment only (which is allowed by the OEM by design).

 

[orezok]

OK, I talked to the dog and she gave me some good ideas. She's smarter than most.

We will now do one final demonstration on shock loading of the bearings dependent upon axle length. We are simulating running over a rock with the rear tire. Now this is just a demonstration of concept so no yada yada about well that isn't reality.

Take a broom and hold it horizontally. Hold it at the balance point so that the weight of the head balances the weight of the broomstick. This is so we start out in a no torsional condition. Your hand is now representing the inner and outer bearing in the tractor case, about 4" apart in this demonstration. Now have someone take a 3# hammer and hit the broomstick 4" from your hand which represents the distance from the outer bearing to the tire. OUCH that hurt and maybe even knocked the broom out of your hand.

When you hand stops hurting pick up the broom again and have that same person hit it 2' out from your hand which represents a longer axle in an exaggerated way. Hmmm... that wasn't bad. A little sting but I could handle that all day.

That's it folks. Your final physics lesson.

I'm out of here. Bye

 

[jenkinsph]

OK, I talked to the dog and she gave me some good ideas. She's smarter than most.

Talk to the dog some more, you may eventually listen to what was said and develop a better understanding of what was said. Explain that a large dog has two bones in its jaws with one sticking out out each side of its mouth. If the bones are longer she has a better chance of prying the jaws open. The large dog may then drop one of the bones and she can take off one of them.