Tracy wrote:

It looked like what happens when two pieces of metal rub

together without sufficient lubrication. ---------

  Even more confusing to me was the fact that the spalling

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

at

one

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

and

was completely gone on the other half.

Tracy, I had a similar pattern on my Ross sun gear which I believe is
caused by "hard mounting" the planetary gear set, rather than letting

them

self align. In essence, the majority of the load is being taken by the

one

planetary gear that is closest to the sun gear thereby contacting the

sun

gear sooner than the others. Paul mentioned that you epoxied the

planetary

gear holder outer teeth to the case which may have caused them to not

self

align so that the load is shared equally between all the planetary

gears.

I modified my late model Ross (which hard mounts the planetary gear

holder)

so that it could move slightly, so that it would self align. So far

this,

plus the sun gear oiling change, is working, but I only have about 25

hrs

on it. My gbox temps have dropped as well.

Chuck

Very Interesting Chuck.   I'm still not able to envision how the
wear/galling pattern could be caused by an off-center planet carrier.  I see
how this would cause the load to be concentrated on one or two planets but
the sun gear wear should still be distributed around the entire
circumference since it is ( of course) turning.

Ahah! it just occurred to me that if the sun gear were not concentric to the
input shaft, this is EXACTLY the wear distribution you would get.
Unfortunately I did not take pictures of the wear before sending it to Ross
for repair and did not think to check the concentricity of shaft & gear.

Don't know how you arranged for the planet carrier to float but make sure to
check for system lash buildup.  Ron Gowan's Ross drive almost wore the
 off the carrier from jittering around in the "floating
mount" system.  This happened in about 200 hours of operation.

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

As I recalled I mentioned that possibility Tracy :-)
"The failure you describe Tracy is very mysterious indeed. Perhaps the sun 
gear was not concentric with the input shaft."

I wonder why those mounting fingers don't wear out in the auto transmission?
Perhaps Ron Gowan had other problems. Perhaps a ring gear that had
run out causing the planet carrier to orbit.

As I recalled Chuck just drilled the holes for the bolts holding the
planet carrier to the psru housing over size.

Paul Lamar
 
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