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View Full Version : How do you replace bearings in a TEFC motor?



Jim Stabe
06-11-2010, 10:20 AM
I have a 1 1/2 hp TEFC motor that is making a squealing noise when the drive belt is tightened. I looked on the internet for an hour last night to find instructions, a diagram or something to show how these things go together but no luck. Once I get it apart I think I can deal with the bearings. Do these motors have brushes?

Jim

RobbieKnobbie
06-11-2010, 10:31 AM
No brushes in an AC motor, and if its 3 phase there won't even be a centrifugal switch.

Bearing replacement is straightforward: remove the end caps, they're usually held on with four bolts. Slide the caps off and the bearings will be right there.

Jim Stabe
06-11-2010, 11:27 AM
No brushes in an AC motor, and if its 3 phase there won't even be a centrifugal switch.

Bearing replacement is straightforward: remove the end caps, they're usually held on with four bolts. Slide the caps off and the bearings will be right there.
Thank you, I was hoping it would be that easy. It is a single phase motor so what do I have to do to deal with the centrifugal switch?

Jim

lakeside53
06-11-2010, 12:54 PM
The switch won't even be be in the way. Undo the 4 bolts/nuts, slide out the rods, then tap the shaft end with a rubber hammer to separate the casing,

You'll likely need a bearing or other puller to get the bearings off the shafts (housing is loose to allow thermal exansion of the rotor, shafts are tight - the bearings stay with the shaft). Don't forget to put back the wave washer back inside one of the end bell housings. A small amount of grease is required inside the end-bell bearing housings.

Jim Stabe
06-11-2010, 01:41 PM
The switch won't even be be in the way. Undo the 4 bolts/nuts, slide out the rods, then tap the shaft end with a rubber hammer to separate the casing,

You'll likely need a bearing or other puller to get the bearings off the shafts (housing is loose to allow thermal exansion of the rotor, shafts are tight - the bearings stay with the shaft). Don't forget to put back the wave washer back inside one of the end bell housings. A small amount of grease is required inside the end-bell bearing housings.
Perfect. Thank you very much

Forrest Addy
06-11-2010, 02:25 PM
HOLD IT!! Before you open the motor:

If "it" squeaks when the belt is tightened, chances are it isn't the bearngs. Bad ball bearings are noisiest when unloaded. When loaded they may rumble but only if the failure is advanced. If they squeak, look for dusty rust around the shaft which generally means they been run dry for some time. Regardless, there are several failure modes for ball bearings but usually they get quieter when loaded.

Try rubbing bar soap on the flanks of the belt before you tear into the motor. The soap acts as a poor lubrcant and silences belt squeak. .

Jim Stabe
06-11-2010, 03:11 PM
HOLD IT!! Before you open the motor:

If "it" squeaks when the belt is tightened, chances are it isn't the bearngs. Bad ball bearings are noisiest when unloaded. When loaded they may rumble but only if the failure is advanced. If they squeak, look for dusty rust around the shaft which generally means they been run dry for some time. Regardless, there are several failure modes for ball bearings but usually they get quieter when loaded.

Try rubbing bar soap on the flanks of the belt before you tear into the motor. The soap acts as a poor lubrcant and silences belt squeak. .
Can I squirt lube at the end of the shaft or will that hurt something? I'm using a link belt for the drive if that makes any difference

lakeside53
06-11-2010, 11:31 PM
Yes, I've put some light machine oil on the ends.

If that doesn't work, I find is just as easy to bust a motor open than play guessing games.