Babbitt pedestal bearing maintenance

[Thedroid]

What is the proper way to maintain and measure these types of bearings? We have an 8" and a 10" bearing supporting a 9 ton rotor turning at 180 rpm. The bearings are split with two oil rings for lubrication. Average clearance is about .045" measured in 3 places on each bearing. The journals show signs of wear, with the larger bearing having definite wear from the oil rings, and the smaller showing signs of pitting and waviness. I believe the 8" journal suffered severe damage years ago, and was built up and turned back down. I have no documentation stating acceptable clearances, but .040 seems a little loose. We are experiencing vibration by the motor, but I am unsure if it's coming from the motor. We only measure the oil temp, and it average about 120F. These bearings have been in service for probably 20yrs since they were last re babbitted, and I don't think anyone here has the experience to say whether they are fine, or should be addressed. I'd like a specialist to come out next year, but I'd like to educate myself first.

 

[caoimhin1]

General rule of thumb for diametral clearance on hydrodynamic bearings is 1/1000 of the bore diameter. But application conditions, lubrication, speed etc should all be considered when selecting a clearance.
So 1/1000 of 203mm is 0.203mm. So your measured clearance of 1.01mm is somewhat slack. (Sorry, I don't understand imperial units, hence conversion).

 

[Thedroid]

I thought so also. I have some of the original prints of the bearing, but clearances are not listed. These bearings were built about 50 yrs ago and have been relined several times. Heres a picture of the good looking journal. I wish I would have taken a pic of the other one, and also the babbitt surfaces.