Ball Bearing question.

[kernal]

My guess: hybrid bearings with ceramic balls are electrically insulated and not subject to arcing damage by stray voltage as steel bearings are. The hybrid bearing would be on the motor side of the shaft for this reason. This bearing is in effect the support bearing for the commutator (armature) on that side of the motor. Again--a guess.

[JohnnieB]

Originally Posted by kellybell

Are you sure the bearings in the axle aren't making the offending noise?

The noise doesn't happen when the rear wheels are off the ground, but as the cart is driven by slowly, it sounds like it is coming from the other side no matter which side I am standing on. When the panel over the motor area was removed, it was louder and better defined, but I didn't try to localize it closer then the top part to the differential.

Having a troubleshooter mentality, it rubs my fur the wrong way to Poke-n-Hope, but that is exactly what I am doing by replacing the bearings without actually proving one or both, good or bad.

[JohnnieB]

Originally Posted by KLA

Hi JohnnyB,

It could be because the motor side bearing sees higher loads than the other side of the input shaft. Basically the engine torque creates a higher side load on on the bearing at the motor side because the intermediate shaft gear sits close to the side.
In addition that bearing has to support the rotor in the motor. So the torque fluctuations from the magnetic field switching also load that bearing.

Originally Posted by kernal

My guess: hybrid bearings with ceramic balls are electrically insulated and not subject to arcing damage by stray voltage as steel bearings are. The hybrid bearing would be on the motor side of the shaft for this reason. This bearing is in effect the support bearing for the commutator (armature) on that side of the motor. Again--a guess.

Thanks guys, the fog is starting to clear. I wasn't taking the rest of the gears train consideration when visualizing the load angles or the effects of eddy currents generated by the magnetic fields.

The two ends of the shaft are electrically the same, but not magnetically the same due to the location of the source of the magnetic field (motor), so the eddy currents are higher closer to the motor. A hybrid bearing on the motor side would minimize metal migration between the steel motor case and the aluminum differential housing.

Perhaps it was an attempt to keep the splines from welding themselves together so firmly. However, I don't know if similar metals migrate when electric current passes though them like dissimilar metals do, but metallurgy isn't one of my long suits either.

[kellybell]

Just a silly question, maybe, but are you sure the bearing is ceramic? I think you can test it with a magnet. Maybe its not! Just grasping at straws......

[dmi518]

ezgo may get the diffs assembled from dana. Could be yours has a ceramic bearing cause thats what Dana feels works best considering its the bearing that gets the least amount of lubrication from the diff oil. just a thought.

[JohnnieB]

Originally Posted by kellybell

Just a silly question, maybe, but are you sure the bearing is ceramic? I think you can test it with a magnet. Maybe its not! Just grasping at straws......

No, I've not taken the existing one out yet.
As mentioned in Post #1, I noticed when ordering that EZGO said the part had ceramic balls. Something I was previously unaware of.

It doesn't actually matter if the existing bearing has steel or ceramic balls, the one I am installing has ceramic balls.

My quandaries are:
1. Why is a hybrid bearing being used in this application?
2. If there is a valid engineering reason for the first question, why not use hybrid bearing on both ends of the shaft?
3. Depending on the first two answers, would it be worth my time, effort and expense to identify and locate a hybrid bearing for the other end of the shaft and install it?

Basically, I am an efficiency nut and hybrid bearings may be a way to make my cart (and others) a modicum more efficient.

Who knows, maybe hybrid bearings throughout a drag cart might shave a few hundredths of a second off the elapsed time in an 1/8 mile or add a MPH or so to the top speed, or in my case, a slightly longer range.

[JohnnieB]

Originally Posted by dmi518

ezgo may get the diffs assembled from dana. Could be yours has a ceramic bearing cause thats what Dana feels works best considering its the bearing that gets the least amount of lubrication from the diff oil. just a thought.

That is a possibility. It explains using a sealed (permanently lubricated) bearing, however sealed all steel bearings also exist.

Could be whoever spec'd the sealed bearing, simply picked one with the proper dimensions without checking the materials it was constructed with.

[beach cart]

Johnnie not sure about the ceramic bearings, but when I worked in a rewind shop for sub's, bearings were not ball type, many exotic combos my security clearance did not touch. There was always a relationship with, noise heat and surrounding systems that impacted the reason for the particular type and style too stay quiet but also heat generation in and outside the sleeve or space the bearing set.

[JohnnieB]

Originally Posted by beach cart

Johnnie not sure about the ceramic bearings, but when I worked in a rewind shop for sub's, bearings were not ball type, many exotic combos my security clearance did not touch. There was always a relationship with, noise heat and surrounding systems that impacted the reason for the particular type and style too stay quiet but also heat generation in and outside the sleeve or space the bearing set.

I ran into some rather exotic stuff while in USAFSS that wasn't commercially available until many years later, but the only restrictions I had were need to know and I needed to know.

However, I think I've got this one figured out.
Hybrid Ceramic Ball Bearings have numerous advantages over Steel Ball Bearings, but the fact that a hybrid bearing is only used on one end of the shaft eliminates most of them from being a valid reason for using a more expensive bearing in this application.

Put a conventional (steel) ball bearing assembly in an alternating or pulsating magnetic field and the races will erode into a washboard like pattern, so the motor side bearing on the input shaft might have been failing before the warranty expired. The hybrid bearing costs twice as much, but warranty repairs are expensive and the increased cost of the bearing can be passed along to the customer anyway.

That may not be entirely correct, but it is close enough to satisfy my curiosity.

[beach cart]

Sounds like a pretty good explanation. A few extra bucks for oem or better has never failed me.