Tires Worry about tires

[W5FL]

You are right but your analogy is very wrong. I hope you are an engineer because I am and I will take you through this one because it is extremely important that others understand this issue properly.

Read the post I made above. It isn't a fulcrum, it is a summation of forces and moments and if they don't balance the tractor falls over and the loader will probably keep it from hitting the ground.

For a stable configuration (rear wheels on the ground) the load is NOT increased on the front. <font color=red>The reason it is in your analogy is that it is NOT a stable configuration. </font color=red>

<font color=red>Please do not mislead others into thinking that adding weight to the rear tires has ANYTHING to do with loading on the front tires - it doesn't.</font color=red> It is a simple case of Statics 201 that for any case that is stable, adding weight to the rear tires ONLY adds weight to the rear and increases the stability.

The reason your analogy looks correct ,although it is not, is that the tractor is already setting on it's nose (obviously unstable)and adding enough weight to bring it back down to a stable condition does put additional weight on the front tires as that is the ONLY way to bring it back to the ground.

Add all the weight you want to the rear tires or on the 3 point and for the same amount of weight lifted on the loader, not one ounce more will be on the front tires. Whew ---I'm about to start lecturing. /w3tcompact/icons/blush.gif

p.s. If your rear wheels ever come close to coming off the ground with a bucket full, you need to totally re-evaluate your tractor ballast as this is a very dangerous situation.

 

[Anonymous Poster]

Please note that I indicated that the points I made pertained to a configuration where the tractor was LIFTING the rear. With the rear in the air, it IS a fuclum. Other than that, I beleive we are saying the same thing.

Because the rear tires are compressible, once they touch the ground, there is only a very slight load transfer to the front until compression equilibrium is acheived.

I agree that it is important that people understand this. The fact of the matter is, if a tractor is routinely lifting the back end, putting weight on the rear WILL increase loading on the front tires during periods of load which would have lifted the rear before weights were added. Argue with your statics and dynamics book not me.

And yes, I have been a practicing engineer for over 20 years.

 

[Bird]

Are you engineers tryin' to confuse folks?/w3tcompact/icons/laugh.gif I'm not an engineer, but do have enough schoolin' to know you're both right, but talkin' about different scenarios, as to whether or not there's still some weight on the back tires and whether the fulcrum is the front axle or the rear axle. As I see it, the important point is to have enough weight at, or behind, the rear axle to keep the back tires firmly planted on terra firma.

Bird

 

[JimBinMI]

Bird,
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Thanks, we needed that! JimBinMI

 

[PaulB]

I still like the picnic table bench analogy. If I am sitting on the end of a picnic bench (I am the "front tires") and my cousin Mildred parks her fat @ss on the other end of the picnic bench BEHIND THE REAR LEGS OF THE BENCH , I get lifted up in the air. If she slides her butt over closer to mine so she is now between the legs of the bench, she is adding weight to both legs of the picnic bench. Seems that weight on the 3 point would do the same thing, i.e. make the front end LIGHTER, while weight in the rear tires will only make all 4 tires handle more weight. am I on track here?.

 

[Bird]

Duh, sorta. Weight directly on, or over, the centerline of the rear axle, i.e., in the rear tires, won't noticeably change the weight on the front tires (just as Mildred doesn't change the weight on your end of the bench as long as she's sitting directly over the legs on her end), but any weight behind the centerline of the rear axle will reduce the weight on the front tires unless there is so much weight to start with, out in front of the front tires, i.e., in the loader, that the front axle is the fulcrum, and the weight in the front has lifted the rear tires, in which case added weight behind the rear axle adds weight to the front tires until the rear tires come back down firmly against the ground, and then at and after that point, additional weight added behind the rear axle, i.e., on the 3-point, reduces the weight on the front axle. Does that sound as confusing as it I were a registered professional engineer?/w3tcompact/icons/laugh.gif

Bird

 

[gordon]

Makes perfect sense to me, about like the Greeks and that leverage stuff. Right? Boy Bird you really make things sound simple, You should have been an engineer but if you were I wouldn't be able to understand you. u know

 

[MChalkley]

Mildred is not happy. /w3tcompact/icons/frown.gif

 

[PaulB]

Bird - thanks for the excellent clarification
Mark - you wouldn't be happy either if you saw her!

 

[JerryG]

Alan, I put wheel weights on my tractor last week and the way I did it ran me about a dollar a pound. It made a lot of difference in the slope stability of the tractor. It is stable now in places that I was afraid to go before.