Does widening front end stress axle/bearings more?

[Gary Fowler]

Yes, but when you reverse (or swap) the tires to make a wider stance the distance between the center lines hasn't changed, it just the center line of the tire has moved from one side of the bearing's center line to the other. The offest distance is the same in both cases. Same distance = same torque on bearings.

This is what those on the "damage the bearing" side of the fence don't seem to understand. The tire rims are dished just for the reason that they can be narrowed or widened. A tractor rim is dished to be offset for the single purpose of widening the tires. If it is unacceptable to widen the tires, the manufacturers should make the dish centered so swapping the tires from side to side wouldn't affect the width since they don't do that, it is obvious that they do intend for the rims to be put on wide or narrow.
The "fact" that bearing are ruined by widening is just an Urban Legend propagated by those who know nothing about tractors except what they have read somewhere or other and don't even think about the physical properties that they are claiming to happen. I suppose someone would have to do an actual size sketch of the lever action that the offset is producing and then measure the torque value that the tire is exerting in each direction to prove the reverse torque amount.

 

[slowzuki]

The contact patch has moved out, the centreline of axle has not therefore there is a larger bending moment on the axle which means the bearing have to resist the load + the bending moment.

Moving tire out = more lever length for tire loads to act on bearings.

I'll use my L5030 as an example, with the tire at the normal spot its pretty well centred. If I'm at max load with my loader I've got about 9000 lbs on the front axle with 4500 lb on each side. With the rims centring the tread with axle centreline that puts about 2250 lb per bearing more or less.

If I flip my rims to gain about 4" per side, I now have bending with 2250 lb up from tire 2250 lb up from inner bearing and 4500 lb down on outer bearing (assuming the bearing are 4" apart which is close)

These aren't exact numbers but it basically doubles the loads on the outer bearing bearings.

Yes, but when you reverse (or swap) the tires to make a wider stance the distance between the center lines hasn't changed, it just the center line of the tire has moved from one side of the bearing's center line to the other. The offest distance is the same in both cases. Same distance = same torque on bearings.

 

[slowzuki]

That is not why they are dished. Most of the manufacturers include a statment saying to only use loader with adjustable rims in narrow position for removable centre models. Dish rims usually say do not reverse the rims.

Even my large ag tractor warns about excessive axle bearing loads with the rims adjusted wider.

They can't "centre" the rims to prevent swapping as the steering axis wouldn't line up with the tire contact patch.

This is what those on the "damage the bearing" side of the fence don't seem to understand. The tire rims are dished just for the reason that they can be narrowed or widened. A tractor rim is dished to be offset for the single purpose of widening the tires. If it is unacceptable to widen the tires, the manufacturers should make the dish centered so swapping the tires from side to side wouldn't affect the width since they don't do that, it is obvious that they do intend for the rims to be put on wide or narrow.
The "fact" that bearing are ruined by widening is just an Urban Legend propagated by those who know nothing about tractors except what they have read somewhere or other and don't even think about the physical properties that they are claiming to happen. I suppose someone would have to do an actual size sketch of the lever action that the offset is producing and then measure the torque value that the tire is exerting in each direction to prove the reverse torque amount.

 

[check]

I suspect that the difference is negligible, simply because our wheels are not 10 feet wide.

However, there still would be the difference. And that difference has to do with reversing the direction of torque. The tractor suspension and related steering parts were designed with the torque going in one direction. So, perhaps if you change the direction of the torque, you will put more stress on certain parts, specifically the parts are not intended to be pushed/twisted up but rather down or vice versa.

 

[RaydaKub]

This makes no sense. You state that the rim is centered with the hub but if you flip the tire around it puts more stress on the bearing. If it is centered, flipping it would do nothing. In fact the rim is not centered on the hub but is dished to one side so that when installed in one direction the bolt hub is almost flush with the edge of the rim, therefore flipping it would put opposite but equal on the bearings. This is true for welded or adjustable bolted on hubs. The center is dished to one side. I agree with the OP(CobyRupert) in that the same amount of strain is on the bearings just in opposite direction. What does change is the steering stresses since the tires are wider apart, it puts more strain on the steering arms to turn.

The only way it would put more strain on the bearings is if one side of the bearings is smaller than the other, IE inner bearing is smaller than outer or vice versa. If this is the case then it would put significantly more strain on the smaller bearing when the wheels are reversed.
When I reversed the rims on my Yanmar 4220, it significantly increased the steering load making it harder to turn when setting still but I never had any bearing or load issues by so doing. I like the have the front and rear tires the same width because it is easier to judge where the rear tires will track and also the mower which is the same width as the tractor stance. This is especially handy when mowing tightly between obstacles, if you can get the front tires between, you know the rear and the implement will also fit.

Let me clarify, again only speaking in general terms because each model is going to be different. The rim may be centered on the hub BECAUSE of the dish. Reversing the dish moves the rim out from this centered position or we wouldn't be having the discussion. In practical terms if you sat down in front of the rear tire and visualize the force there will be a torque on the front axle. The weight of the front end is pushing down on the spindle which is closer to the COG than the tire is. The tire is pushing it back up from a position outside the upright spindle. If your axle were to snap off the spindle, it is this torque that accomplishes it. If you move the wheel out further this torque increases because the lever arm of the tire has been increased. The torque of the wheel on the axle can only be applied through the bearings. Whether that is enough to cause problems or not may depend on many other factors.

And the steering difficulty makes perfect sense.

 

[slowzuki]

I'm not BS'ing here either, I have ruined the bearings in the front axle of my Kubota and rebuilt it. In my case it was complete disintegration of the outer bearing and cage.

 

[DavesTractor]

Not really the question, but most folks ask this question because they are trying to gain stability against a sideways tip over. Yet the front axle pivots and there is no gain in stability until the axle is all the way against the pivot stop. By then, are you going over anyway?

Obviously it adds stress to the bearings, how much depends on how much additional width and the duty cycle of the tractor.

 

[CobyRupert]

Let me clarify, again only speaking in general terms because each model is going to be different. The rim may be centered on the hub BECAUSE of the dish. Reversing the dish moves the rim out from this centered position or we wouldn't be having the discussion.

...but if the rim is centered on the hub because of the dish, it's going to be centered when you turn it around (or swap it) around, and you haven't changed the width . That's the point, I'm trying to make, it's offset when in narrow, and it's offset just as much when its turned around = same amount of torque on bearing.

That is: When it's dish in (narrow) the torque wants to fold the bottom of the tires in. When you swap the "dish" and widen, the torque wants to collapse the bottom of the tires out. Your offset is the same in both cases, just on a different side of the vertical axis of the bearing, and thus the torque is the same on the bearing, just in a different direction.

 

[DT86]

I personally know a guy who broke the front axle at the steering knuckle on a Case Jx series because he set the wheels out all the way.

Paid out of pocket for repair too because it was beyond the recommended width in the operators manual.

I don't know anyone who has broke one in the steering knuckle with their wheels narrower, just saying.

 

[CobyRupert]

That is not why they are dished. Most of the manufacturers include a statment saying to only use loader with adjustable rims in narrow position for removable centre models. Dish rims usually say do not reverse the rims.

Even my large ag tractor warns about excessive axle bearing loads with the rims adjusted wider.

They can't "centre" the rims to prevent swapping as the steering axis wouldn't line up with the tire contact patch.

Yes, I think all agree that a removable center type rim will change the geometry and bearing torque (stresses), but for the sake of this discussion, let's not confuse the issue and stick with just reversing the "dish".