Dry Well in Gearbox? 2

[ahsanb]

Hi Guys,
Can anyone explain to me what is a dry well in a gearbox and what is there use in a gearbox?

 

[Tmoose]

Not sure if the terminology is correct, or translates consistently, but I'm aware of some agitator gearboxes that have a large tube with an open upper end surrounding the vertical or inclined output shaft. The purpose is to keep the gear oil away from the output shaft and specifically the bearing, to allow grease lubrication without heroic sealing measures.

 

[MiketheEngineer]

Not sure if I understand either - but many gearboxes have a "lower" area where any metal chips can fall and not be sucked back into the flow??

 

[tbuelna]

ahsanb,

With regards to gearboxes, the term "dry well" describes a sort of scupper or annular cavity formed in the housing around the outboard side of a shaft oil seal. Beyond the seal and cavity, the dry well has a close fitting opening that the shaft passes through. The dry well is basically a shield that helps to keep external debris and moisture away from the seal.

Aircraft gearboxes sometimes use pressurized air labyrinth shaft seals (the air pressure "blows" the oil back into the gearbox). These shaft seals are non-contacting, and have no friction and very long life. But they also weep oil when the gearbox stops operating and their air pressure feed halts. These gearbox seals must have dry wells to collect this lube oil seepage, so that the inside of the nacelle stays nice and clean.

Hope that helps.
Terry

 

[ahsanb]

Thank you very much for your valuable advice. I have seen dry well in gearboxes used in my plant's agitators and yes dry well in their case is surrounding the output shaft.

 

[Tmoose]

Picture of "our" gearbox with inclined low speed output shaft