lubrication of planetary gearbox

[rmetzger]

We are designing a planetary gearbox with circulating oil lubrication (shared with the engine) and I'm looking for any particular trouble points that may arise / words of advice. Input speeds are 22000 Rpm with a 4000 ft/min surface speed at the gear pitch (max). The oil used for lubrication will be a Mil-L-23699 or Mil-L-7808. Output seal will be a standard Lip seal (gear reduction will be 7.5/1) and input seal will probably be a carbon face seal.

 

[Philrock]

While it is not uncommon to have a common oil supply for engine and gears, it is far from optimal practice. Engine oil tends to be quite dirty and will reduce gear and bearing life. Ideally, you should have separate sump, filter, and pump systems. If you can't avoid separate systems, be very careful about filtering the oil that goes to the gearbox.

 

[plasgears]

Recommend separate lubes because of their different applications. A light grease or heavy gear oil lube would not require forced circulation. I would also add ports in all elements to encourage migration of the lube.

 

[Tmoose]

" Engine oil tends to be quite dirty and will reduce gear and bearing life."

The original MiniCooper's engine and trans shared oil. They had a big oil filter bypass warning light on the dash, and the legend was the engine needed to be protected from the gear-box's trash.

Since the magnetic drain plug on several motorcycles and cars' trans's and hypoid rear axles generally look like porcupines, sometimes with rear quills, I figure their trash is at least different.