Any needle bearing with an ID that would fit
the ground down sun gear will work. For example a 1.75" bore 2.5"
OD Torrington needle bearing has a static load rating of 26,000 pounds.
Part number NTA2840. Dynamic load is 4640 pounds or more than enough.
The limit speed is 6900 RPM. If you assume the dynamic load

capabilities

are zero at 6900 RPM worst case you would want to use three
back to back. That would reduce the individual RPM to about
2300. The thickness with one hardened thrust washer is
about .078" plus .032" or about .11 per bearing. Three times
that is .33 so you would need that much space plus a bit for
an extra thrust washer between the shoulder on the sun gear
and the Ross bell housing bulkhead. Every Ross appears to be
slightly different so I would need dimensions to determine
how far the sun gear needs to be ground down.

Jerry Hey has a friend with a machine shop. Jerry can you contact him
and ask him if he is interested? I can provide some engineering
details as we have accumulated quite a few drawings of modifications
that are now successfully flying. This modification should be worth
a couple of hundred dollars as the Ross is near useless with out it.

Paul Lamar

Jerry Hey wrote:

  Paul,   I will be glad to give Danny the details.  He does not have
a surface grinder but of course, he knows someone who does.  Out here
in the country we all work together.   Jerry

Tailwind & Rotary Engine Support

http://www.j-winddesigns.com

mailto:j-winddesigns@thegrid.net

A shaft grinder is all that is needed.

Tracy made his own shaft grinder by mounting a low cost 110 volt
bench grinder on the carriage of his lathe. Got a spare bench
grinder lying around?

BTW I looked up the price of those needle bearings in McMaster
Carr Part # 5909K42 $2.98 for the bearing and $1.38 for each
thrust washer.

Paul Lamar

Paul,
What about the hat trick, you know make a bearing holder that looks like a
hat.
George (down under)

That will also work. Slows the RPM difference on a 2.85 as the planet
carrier is rotating in the same direction only slower.

Not good for a 2.17.

Paul Lamar
 
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