please educate me on electric motor sleeve bearing with oil bath & ring

Old ('40s) Century repulsion-start induction-run motor. At each end of the rotor the shaft turns in a sleeve bearing. The sleeve bearing has a slot cut in the top half about 1/4" wide. The bearing sits in a cavity where the bottom inch or so is filled with oil. A metal ring sits in the slot in the sleeve bearing, and is big enough to dip down in the oil. As the shaft turns, the ring slowly turns, bringing oil up to the cutaway slot where it can flow down around the shaft inside the sleeve bearing.

Mine has a 1/2" Gits press fit oil cup at the top center of the oil bath. About at the height of the oil, on one side is threaded a 1/8"NPT Gits oiler. On the other is the first of two 1/8" plugs. The second is bottom center of the oil bath, below the top center Gits cup.

I'm wondering about the use model for these fittings. Obviously, I can add oil in the top center. Redundantly, I can also add it low down on one side. If the oil bath were a clock face the second oil cup would be at 5 o'clock and the upper drain plug would be at 7 o'clock, with the lower drain plug being at 6 o'clock and the upper oil cup being at 12. Here's a picture, sorry for the filth and heavy paint:



My question is: why have two oil cups and two drain plugs?

metalmagpie

Top oil cap is the oil fill... the side is the full level,... and the plug on the bottom is the drain...Phil

Vaguely related question: I have a similar vintage motor, with sleeve-and-ring oiling. It appears to take a pretty thick, dark oil- can anyone suggest a good modern replacement? And preferably one I can get in less than bucket quantities?

Doc.

My guess is there is an extra oiler on top for ease of filling. Without it the motor would have the same issue as the apron sump on my lathe - it would take forever to fill up that huge oil sump through a horizontal passage with such a low head. I imagine the plug on the opposite side exists so the customer can chose which side they want the side oiler to sit on. The bottom is obviously the drain.

Not quite as convenient as the older lift-up covers that they used to use, but less prone to damage and ingestion of debris I suppose.

As far as oil, I'm not sure what the spec is. I imagine you probably want something just thick enough to form a nice little bead at the top wiper that sits above the oil ring. I haven't gotten around to rebuilding mine yet so I don't have any recommendations. Definitely want something with a '1B' or '1A' copper corrosion rating.

Just everyday 30 wt...Phil

Non-detergent straight 30wt or even 20wt. Don't use automotive engine oil, as it suspends the wear particles and keeps them circulating.

Stupid question - would an ISO 100 non-detergent air compressor oil be a suitable substitute for SAE 30 non-detergent? Hell, are they the same thing?

This stuff I think: Lowes

Probably, but hydraulic oil will also work. Main thing is non-detergent. You want any contaminates to settle in the bottom of the cup, not keep getting run through the bearings again.

Finally dug into the motor on my old W&S turret lathe. Both bearing ends have a plug at the top and a plug at the bottom.



In this pic, I've pulled the top plug, and the bottom plug is that little yellowish spot.

What do I lube these with and how much? There are no side plugs as in the OP's example, but I'm assuming I don't just dump oil in 'til it overflows. Do I even use oil? I'm assuming this style doesn't take grease...

Phil, above, says simple 30-weight. I'm assuming this is a case of any oil is better than no oil, but is there something "more correct" I should try to get?

Doc.

I ran my 14 1/2" South Bend lathe spindle for forty years with barely measurable wear on its bronze bearings by keeping the cups full of Mobil DTE 24.

Bill

As I understand where oil-ring bronze bearings are concerned, keeping the oil level just below the bottom of the shaft is ideal. Any higher and oil will seep out through the shaft seals. The oil rings allow the journals to "dry out" when stationary, but keep them wet when running. Lubrication when you need it, reduced seepage when you don't.

Phil in Montana said:

Top oil cap is the oil fill... the side is the full level,... and the plug on the bottom is the drain...Phil

Click to expand...

The plug at 7 o'clock exists so you can swap the Gits fill level check to an alternate, more accessible position.