Egon
Epic Contributor
Talking to the Dawg sounded good so I did. She said stop this nonsense and let's go for a beach walk. Smart Dawg!
Tires A physics question of leverage
- Thread starter lennyzx11
- Start date
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LD1
Epic Contributor
Late to the party....
Cannot for the life of me even figure out the original question. If the wheels have the ability to go to 65" without spacers, and with spacers.....re-configure the hub/rim to also be at 65"......debating the difference???????
Only difference I see is money wasted on spacers.
As to extending the axle.....it most certainly does add load to both the inner and outer bearings. An upward force on the outer, and downward force on the inner.
If the tractor weighs 2000# in the rear, Thats 1000# over each tire. According to newtons 3rd law that also means that the ground is ALSO pushing UP on the tire with 1000# of force. And THAT will no change no matter the spacing.
So...with orezok's broom handle, Grab it with your right hand near the end, and the left hand maybe 15" up the handle. These represent the bearings (right hand being inner and left hand being outer). Now have someone press upward a few inches beyond your left hand. Your left hand has an upward force trying to pull it out of your hand, and your right hand (inner bearing) is being forced downward.
Now have your friend go further out, and apply the SAME upward force......You WILL see alot more force on your hands trying to hold the broom.
Cannot for the life of me even figure out the original question. If the wheels have the ability to go to 65" without spacers, and with spacers.....re-configure the hub/rim to also be at 65"......debating the difference???????
Only difference I see is money wasted on spacers.
As to extending the axle.....it most certainly does add load to both the inner and outer bearings. An upward force on the outer, and downward force on the inner.
If the tractor weighs 2000# in the rear, Thats 1000# over each tire. According to newtons 3rd law that also means that the ground is ALSO pushing UP on the tire with 1000# of force. And THAT will no change no matter the spacing.
So...with orezok's broom handle, Grab it with your right hand near the end, and the left hand maybe 15" up the handle. These represent the bearings (right hand being inner and left hand being outer). Now have someone press upward a few inches beyond your left hand. Your left hand has an upward force trying to pull it out of your hand, and your right hand (inner bearing) is being forced downward.
Now have your friend go further out, and apply the SAME upward force......You WILL see alot more force on your hands trying to hold the broom.
orezok
Elite Member
Is someone beginning to see the light?
Yes, there is 1000# of upward force exerted by the tire no matter the axle length, but with a longer axle it takes LESS upward force at the tire to raise the tractor at the longer length axle, hence less shock load on the bearing. Now this is not realistic as the tractor is NOT a fixed item but of a fixed movable weight. If you wanted to move a rock with a lever, which would take less force to move it? A short lever or a long one?
LD1
Epic Contributor
I think you mis-read my post. As nothing you have said so far I agree with.
You have your thinking all backwards.
IF the tractor rear weighs 2000#, thats 1000# over each rear tire no matter how the wheels are spaced (as long as they are the same).
So if there is 1000# over that wheel, there is NO way to lift that wheel unless 1000# is applied to that wheel in an upward direction. Sure, you could use a lever or whatever, but you are still applying 1000# upward AT THE WHEEL.
The issue isnt what happens beyond the wheel. But between the wheel and the CL of the tractor. The further out the wheel is, the more leverage it has on the bearings.
Remember, no matter the axle/wheel spacing, it takes 1000# to lift that tire regardless. If that wheel is 12" away from the first bearing that 1000# multiplies more than if the wheel is 6" from that first bearing
orezok
Elite Member
No, I think you do get it. It takes 1000# at the wheel to raise the corresponding 1000# at the bearing. It doesn't matter how long the "lever" is, it only takes 1000# to raise the tractor so no additional load on the bearing. The problem most people are having in their thinking is that the tractor is fixed object and a longer lever exerts more force on the bearing. The bearing moves as soon as the 1000# required to raise it occurs.
LD1
Epic Contributor
But if the 1000# is further from the bearing, the axle acts as a lever on the bearing. So exert 1000# on the tire connected to a short axle/lever that is close to the bearing means not much load on the bearing. Add spacers and distance, now the axle acts as a longer lever. Still requires 1000# exerted at the tire, but leverage means the bearing sees more force.
LD1
Epic Contributor
Are you saying the load at the bearings is the same on the top drawing as they are on the bottom?
orezok
Elite Member
Yes. When the upward force reaches 1000# at the bearing, the static load amount, the tractor begins to rotate. The force cannot exceed 1000#, it can only match it. Newtons Third law - To every action (force applied) there is an equal but opposite reaction (equal force applied in the opposite direction).
LD1
Epic Contributor
You need to re-think that then.
1000# pushing up on a tire/axle 10" from outboard bearing and 25" from inboard bearing somehow has the same bearing load as...
1000# pushing up on a tire/axle 20" from outboard bearing and 35" from inboard bearing......
Since when did leverage no longer apply? Leverage makes the load.....in both cases.....exceed 1000# on the outboard bearing. It just exceeds it by a greater amount on the one with the longer lever arm.
orezok
Elite Member
Leverage never applied. Forget that premise. That is something that numerous people confused themselves with. We're not moving an immobile rock here. It's strictly an action and reaction situation on the bearing. Do you think Newton is wrong?
