Bill, maybe you can help me better diagnose what was happening on my

Ross

drive.  I'm not sure if I'm using the technically correct term

(spalling)

for what I saw.  It looked like what happens when two pieces of metal

rub

together without sufficient lubrication.  Ross said it was due to an
improperly machined oil passage in the drive which blocked oil from

getting

to the sun gear.   Even more confusing to me was the fact that the

spalling

was only on half (of circumference) of sun gear.  It was most sevear at

one

point and faded away on either side of this point for about 90 degrees

and

was completely gone on the other half.  I was unable to imagine any

senario

which would explain this other than some odd harmonic oscillation along

with

some misalignment.  This might have been possible because the prop shaft
thrust bearing race was like a wash board.

Tracy Crook
rws@altavista.net
www.rotaryaviation.com

Bill is incommunicado for awhile Tracy. Up in the Colorado mountains.
Spalling as I recall is a pitting action where the failure is a
surface compressive failure of the material. Like Bill said. To quote the

Sky Ranch

Engineering Manual "spallig is a metal fatigue failure and not a

lubrication failure."

It is commonly seen on camshafts or valve lifters due to high contact

stresses.

If it was due to resonance you probably would see the failure on both

sides of the

sun gear as the rotary fires twice per rev.

Did this happen before or after you epoxied the planet carrier into the

housing?

Sounds like a misalignment of the sun gear and planets.

Paul Lamar

Sounds to me like the sun is off center compared to the planet carrier so
all the load is being carried on the one area.  The planets will run tight
on that side and loose on the other.  The definitions of spalling given are
correct but it sounds like that is not what you have.  Maybe you could get a
good picture for better internet diagnosis.

Jeff Spitzer

 
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