View Full Version : Okay to replace ball bearings with needles?

04-18-2003, 02:49 AM
I enlarged the shaft of an electric motor from 0.5" to 0.75"...the only thin section bearing I found (Timken SFSS 12)that had a 3/4" bore and 1.25" outside diameter hasn't been made for seven years. Would there be any adverse effects to replacing this ball bearing with a needle bearing? Or should I do the work necessary to use a ball bearing...either machine the motor end plate to receive a larger bearing or machine some sort of adapter.

04-18-2003, 07:30 AM
A couple of things that may be a problem:

I don't think needle bearings can carry any axial (thrust) load to speak of, so that may be an issue.

Many needle bearing depend on the shaft to be one of the bearing races, i.e. the needles ride directly on the shaft. If so, the shaft needs to have a "bearing quality" surface or life expectancy will be pretty short. If the needle bearing you're thinking of using has an inner bearing race, of course, then it isn't an issue.

04-18-2003, 02:41 PM
What was the width you have to work with?
Just an idea:use a 6003 bearing
bore 17=0.669"
od 35=1.377"
width 10=0.393"
Turn the shaft to fit and bore the bell housing to fit.(that is if you have the material to do it)
You can use a 6203-0.750(A 6203 with a 3/4" bore)
or use a SAE660 bushing
hope this helps

04-19-2003, 11:46 AM
Hello abn,

I believe most electric motors have 2 bearings in them for support. I would narrow down exactly what you need as in .750 bore and 1.250 od and thickness .xxx From there I would first contact a bearing supplier for they have access to more catalogs that would help you with both bearings. Either a inch or a metric bearing.

Finally I would make at least 1 of those bearings a ball type to absorb the thrust. This would also depend on the application (is it just turning an axle that it is supported itself (pure rotation - "radial" loading) or is there some "axial" loading that motors bearings would see).

We would need to see more details to determine which is easier to do (machine an adapter or machine end plate).

04-19-2003, 11:09 PM
Needle bearings don't resist thrust loads as they are straight cylinders. Ball bearings resist thrust in both directions unless they are angular contact bearings which only support thurst loads in one direction. If you change to a needle bearing on one end you will have half the thrust load capacity assuming the other end is a standard ball bearing. Probably a bad idea to change to a needle bearing if you want the motor to last for a while.

04-20-2003, 01:15 AM
Ask the people you get the bearings ffom. They should know, if they 've got any reliablity.