Motor Ball Bearing Lubrication
Motor Ball Bearing Lubrication
(OP)
Hi all,
I have an older 1/2 HP, single phase, capacitor start motor with ball bearings on the rotor shaft. I don't know how old the motor is but when inspecting the bearings, they seem a bit shy of grease/lubrication.
I was wondering if there are any guidelines for adding/changing lubricant (grease/oil) to the motor bearings that anyone cares to share? I know in the automotive industry when lubricating the wheel bearings, it is strongly advised that all the old lubricant be thoroughly cleaned from the bearing so that the new lubricant doesn't cause any adverse chemical reaction with the old lubricant. I was wondering if the same type of procedure should be done with the bearings in fractional HP motors. And if so, what is a good technique for cleaning the old lubricant from the bearings.
Thanks for any comments.
Newbie Dale 7905
I have an older 1/2 HP, single phase, capacitor start motor with ball bearings on the rotor shaft. I don't know how old the motor is but when inspecting the bearings, they seem a bit shy of grease/lubrication.
I was wondering if there are any guidelines for adding/changing lubricant (grease/oil) to the motor bearings that anyone cares to share? I know in the automotive industry when lubricating the wheel bearings, it is strongly advised that all the old lubricant be thoroughly cleaned from the bearing so that the new lubricant doesn't cause any adverse chemical reaction with the old lubricant. I was wondering if the same type of procedure should be done with the bearings in fractional HP motors. And if so, what is a good technique for cleaning the old lubricant from the bearings.
Thanks for any comments.
Newbie Dale 7905





RE: Motor Ball Bearing Lubrication
Often on motors that small you don't bother with bearing maintenance you just replace them occasionally or when they fail.
You always want to clean out the old grease for the reason stated and because metal fragments (dust) starts loading up the existing grease with predictable results.
Stay tuned: Some actual motor guys will be along shortly..
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
More small motor ball bearings have failed from over greasing than from lack of grease.
Be sure that the bearings are greasable. If the bearings have been replaced with sealed bearings at some time, they may be damaged if you attempt to grease them.
respectfully
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
A race blew up in my hand.. Same damage as a hard hammer blow.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Motor Ball Bearing Lubrication
rmw
RE: Motor Ball Bearing Lubrication
"1/2 HP, single phase, capacitor start motor with ball bearings on the rotor shaft"
Above suggestions are sensible, but with fractional size motor i would rather replace it with new one than recondition it. Ball bearing, such 6204 and below, is inexpensive and it'll never isn't burden you much.
RE: Motor Ball Bearing Lubrication
Many of these smaller machines were manufactured for an OEM and have minor modifications which render them difficult to replace except for going back to the OEM
Respectfully concerning the regreasing process, I have seen poor results with pumping grease until the new grease flows from the pressure release opening. We do not usually look at motors this small but on larger motors, the typical grease relief tube is 1/8" pipe thread and on the ODE on a TEFC unit, there is usually an extended tube to clear the fan cowl. This pipe often offers more resistance to grease flow than the inner seal of the bearing cap forcing grease into the windings. This problem is compounded if EP grease is being used as many of these greases are conductive.
One approach I have used requires that the motor be deenergized. Remove the drain plug, clean out passage with a pipe cleaner and pump fresh grease until evidence of the new grease shows up on a clean pipe cleaner.
RE: Motor Ball Bearing Lubrication
Thank you all for your comments. You've given me a lot to consider. This particular project is a 'hobby' type effort for the moment; however, I'll probably find a good use for the motor in my workshop when I'm satisfied it will work well. I'm leaning toward replacing the bearings as many have suggested ..if I can get the bearings off the rotor shaft. I haven't tried getting the bearings off the rotor shaft yet. After reading some of the other threads on this site I'm wondering if I may have to heat the bearings somewhat if they are what (I guess) one would call a 'shrink fit'. I'll then look up some local motor repair places and internet sources and see if I can locate the necessary bearings. If getting the bearings off the shaft proves too much for my mechanical abilities I'll resort to trying to re-lubricate them.
Thanks again.
Dale7905
RE: Motor Ball Bearing Lubrication
Of course, if you hit anything _but_ the bearing, it could also be a very expensive way to remove the bearing.
For an axle bearing, a 5 lb. hammer is about right. For fhp motor bearings, a 2 lb. hammer should suffice.
Mike Halloran
Pembroke Pines, FL, USA
RE: Motor Ball Bearing Lubrication
Dale? I find the easiest and safest way is to place the rotor horizontaly in a soft-jawed vice with the back edge of the bearing flush with the ends of the jaws, then with 2 crowbars or tyrelevers, one in each hand flick the bearing off using the jaw ends as a fulcrum. You will be surprised just how little effort it takes.
RE: Motor Ball Bearing Lubrication
If you miss, you buy a new motor.
Agreed it's dangerous and risky, but crowbars never fit right, there's never a fulcrum in the right place, nobody can ever find the real bearing puller when you need it, and small motors are often designed in such a way that real bearing pullers won't fit anyway.
Mike Halloran
Pembroke Pines, FL, USA
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
When you have cut the inner race, with the now C shaped secton and the heat, it should slide off, if not, cut the other side.
Sometimes the smaller motors are much more of a problem than the larger ones.
RE: Motor Ball Bearing Lubrication
RE: Motor Ball Bearing Lubrication
If the bearings start to show signs of distress, change them out for new, prelubricated, sealled bearings. Most bearing sizes are readily available as open, or sealed, prelubricated.
In industrial applications ball bearings will run 24/7 for several years.
respectfully