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can overfilling a horizontal sleeve bearing motor cause excess oil usage

can overfilling a horizontal sleeve bearing motor cause excess oil usage

can overfilling a horizontal sleeve bearing motor cause excess oil usage

Title should have been: can overfilling a horizontal sleeve bearing motor cause increased oil addition frequency

I know that on a vertical motor if you overfill the oil, it can result in increased rate of oil loss from the upper bearing which would necessitate increased oil addition frequency per time. The explanation the initial overfill provides a wicking path over the standpipe which allows oil to continue to flow in that path even as the level lowers.

My question is if similar phenomenon applies to horizontal sleeve bearing motors (where the design is that the oil level is below the shaft and oil ring brings the oil over the shaft so it can fill the bearing inlet distribution groove).

Specifically: would routinely filling the oil level too high (for horizontal sleeve bearing motors) increase the required number of oil additions per time? (and if it does, what would be the mechanism)

I know (for horizontal sleeve bearing motoRs) we want the proper oil level for a variety of reasons including proper operation of the oil ring. But my question is not whether or not we should fill to proper level (of course we should). My question here is whether filling to a level which is too high results in need to fill more often, and if so why. If you want to know why I'm asking the question, it's because in order to cope with excess oil addition rate, we started adding oil while running (rather than secured) in order to avoid taking the motor out of service, and the target oil level is not as well defined when the motor is running (all OEM markings for all level are static markings).

So for the question (would routinely filling the oil level too high for horizontal sleeve bearing motors increase the required number of oil additions per time?) my thought is that it should not. My thinking is that excess filling may create increased oil loss initially if erratic oil ring operation causes splashing which creates more droplets and mist that might find there way through seals. But at some point the level is going to drop and at that point I don't see the mechanism for the initial overfill to have any lingering effect to caused increased oil loss. There is no wicking / creepage path from the sump up over a standpipe like there is for vertical motors.

What do you think about that question?

(2B)+(2B)' ?

RE: can overfilling a horizontal sleeve bearing motor cause excess oil usage

electricpete: Depends on the level of overfill. If the level is only to the somewhere between the hanging ring and the bottom of the shaft (or seal), then no - you might get a fairly noticeable drop and then steady state. But if the fill level is above either the shaft or the seal, you can (for a time) develop a wicking path through the seal (as oil moves along the shaft or across the seal itself). Something else that would be immediately obvious from an overfill condition (particularly if the shaft speed is higher than about 400 rpm) is that the oil will appear frothy - gas gets trapped in the oil, causing bubbles. As a result, less-than-perfect lubrication. For pressurized oil flow (high pressure lift or forced lube) situations, overfill WILL result in a wicking path because the oil keeps being dumped into the system from a day tank, which has a much higher volume compared to the amount in a bearing sump.

Converting energy to motion for more than half a century

RE: can overfilling a horizontal sleeve bearing motor cause excess oil usage

Gr8blu - thanks for wandering into my (admittedly convoluted) question.

I estimate it's only 1/8" that would be overfilled (because that is roughly how much the oil level goes down after you start the motor and run it for awhile... and we're filling to the static target while running). I don't think it would reach the level of the shaft / seal. We haven't noticed abnormal foaming in the sightglass or oil ring viewing window, nor any abnormal oil ring movement

No pressurized oil flow.

But we are having to add oil at an accelerating rate on this one motor. We don't have an opportunity to take it out of service to check inspect the seals. I might try decreasing the oil add target to see if that has any effect on rate of required oil additions.

(2B)+(2B)' ?

RE: can overfilling a horizontal sleeve bearing motor cause excess oil usage

electricpete - Glad to (potentially) be of service.

Hmm. From the further information in your second post, I suspect the level within the bearing/sump might not be as much as you think. With the shaft turning, the level in the sight glass is not going to be the true "static" value - what you see could be lower (or more likely higher, since the rotation usually carries a bit of oil into the region of the glass itself) than what is actually inside. If the glass is reading artificially high, you think you're filling up to the 5-gallon mark, but in reality you're stopping at about 4.8 and therefore having to refill more often. On the other hand, if the glass is reading "low", and you're not seeing oil running down the outside face of the bearing bracket below the seal then you might be leaking any excess oil past the inboard seal and thus into the machine (and its windings).

Converting energy to motion for more than half a century

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