Replacing bearings in single phase motors

[Mike Kees]

How difficult of a job is this ? I know three phase motors are real straight forward, are single phase the same ?

[Randall J Cox]

I've done about 5 motors so far .5 - 3 hp. Fairly simple, just take pics of where the spring washers go and what direction and be careful of any centrifugal switch. Also any extended races, etc. If you have taken apart motors before, not hard. I have no training, just followed my nose and was careful and documented so I knew how to get back together. I have not done any three phase so I don't know the diff. Good luck. Randy

[Bruce Wrenn]

As long as they are ball bearing, easy peazy. Oillite bearings require pressing in and out, which means it's a motor shop job.

[Robert Hazelwood]

You need a bearing puller or a three jaw gear puller to remove the bearing, and either an arbor press or differential heat (freeze rotor, heat bearing inner race) to install new ones.

The main difference with a single phase is the centrifugal switch. It's pretty straightforward to remove the rotor from it, but be careful on reassembly with the wires for it. Make a note or take a picture on how it is all arranged as you remove the back of the motor. I have had a wire get positioned in such a way that the switch arms would contact a wire as the motor spins, causing very odd symptoms and eventually breaking the circuit and causing the motor not to start. Had to dig back in and repair the wire.

[Bill Dufour]

I have seen a few single phase motors where you can pull the rotor out one end without touching the centrifugal switch.
Bil lD

[Mike Kees]

So here I am reading the thread after the work is done. I had a post about a week ago about my shaper and vibrations,so replaced the bearings in the spindle today. After putting it back together I found I still had vibration so I took the belt off and determined my motor bearings were shot too. Hence this new post. Right after I posted I went to the shop and pulled apart the motor and removed the bearings. While I was at it I pulled the bearings on my phase converter,it has been howling on wind down for a while. So now I have to say that I wish all my shop stuff was three phase,way simpler in there. I will probably never pay someone to do bearings ever again. ( Only paid once,thankfully.) I do have one more question,has anyone used NTN bearings ? My brother-in -law uses them for everything on his farm,we have a local business that supplies farmers and oilfield businesses that sells them. They have carried them for 25-30 years and everyone seems to love them just as much as SKF.

[Rod Sheridan]

NTN bearings are just as good as SKF.

For electric motors I normally use a C3 clearance bearing...............Rod.

[Ron Selzer]

I have changed bearings in 3 phase motors at work a lot.
Easy peasy 1 phase however always gives me fits
Got 5 pumps on the bench all single phase getting ready to try again

[David Kumm]

I think NTN makes an electric motor bearing with a CM clearance that is within the normal range but a little more precise. Similar to SKF Explorer or Natchi Quest. I'd ask about those. Dave

[Carl Beckett]

I have done a couple now, and have another one I want to do. In addition to replacing bearings, blow out dirt/dust from between the laminations and windings (especially behind the winding wires). Check the wrap/tiedowns of all the winding bundles. If these are decayed you might retie. Then get a can of winding laquer and spray the windings with another layer before putting it all back together.

Maybe. This is what I do at least, but I dont claim to be a motor rebuild expert but others here likely are and can correct me.

[Mike Kees]

I picked up and installed my shaper motor bearings today. Reassembled the motor and installed it. Runs good,no issues. However I may have to pull my shaper spindle cartridge again. When I pressed the bearings I believe that I damaged the lower one. I still have a low vibration and after letting my shaper run for a while I felt the spindle cartridge,it was very warm on the bottom end. Will probably pull it apart tonight and fix tomorrow.At least I know how to do it now.

[Mike Delyster]

Instead of pressing the bearing on heat it up. Lot less chance of damaging the bearing. Putting bearings on a incandescent light bulb and heating the inside race up to about 150F works very well. Working quickly grab it with gloves on and slide it right on the shaft.

[Mike Kees]

Mike thanks for that tip. My brother in law has an old "toaster oven" on the farm that they use for bearings, was going to look for one of those but the light bulb idea sounds far easier.

[Eric Danstrom]

Or use a hydraulic press to press the bearings on.

[Tony Shea]

Need to be careful pressing bearings on without heating the inner race. If you put all your pressure on the outside race of the bearing while pressing it on then this can def damage the bearing. I really like that incandescent light bulb trick.