Gearbox spewing oil...

[x39]

What would cause a gearbox to spew oil through the vent? The box is only filled to the level prescribed by the manufacturer, and similar boxes in the same environment aren't spewing oil. Any ideas? For what it's worth, these are 15:1 boxes mounted on 1750 rpm electric motors. They are outdoors, temps have been fairly mild, high teens low twenties during the day when they are in use.

[agrip]

39 huh same as Jack Benny.
You don't give much info.
Here are a few WAGs

Spewing oil can come from foam.
Additives wear out particularly in high shear situations.

Spewing oil can come from steam.
Water, condensation, passing through worm.

Spewing oil can come from a deflector plate getting loose, and allowing thrown oil to hit the vent passage.

HTH Ag

[Joel]

Perhaps the 'spewing' one has different or contaminated oil in it - and that oil is foaming?

[WJHartson]

In addition to what has been said check the operating temperature of the gearbox. Bet it is running hotter than the others. Could indicate that you have a bearing starting to fail or something misaligned due to wear inside the gearbox. How does the box sound?

Joe

[x39]

No unusual noises from the box, and the guys running the equipment haven't detected any undue heat. I told them to give me a shout next time it happens, because it behaved nicely when I ran it. No water in the oil either, that was my first thought. The box is filled with Mobilgear 634. For what it's worth, the box powers a small capstan head winch on a commercial fishing wharf, and is never under a constant heavy load. Thanks all for the replies.

[This message has been edited by x39 (edited 01-09-2006).]

[wierdscience]

It's almost got to be an overfill then,unless there is water in the bottom you can't see.

[JCHannum]

A gearbox in a high humidity environment can fill with condensation, forcing the oil level up or out. It might be a good idea to check the actual oil and make sure it has not been displaced.

[x39]

I pulled the fill plug on the unit and the oil I could see didn't look milky. Maybe I'd be better off pulling the drain plug and seeing if I get water.