> Paul,

 I have a Ross 2.17 also that needs the thrust bearings.  Checked with Tracy
 as you suggested previously.  He said he was to busy to do it.

 It would seem that with the number of Ross units that are out there, there
 would be someone interested in doing this work on a on-going basis.

 Do you recall the mfg./part number for the needle bearings that were finally
 settled on by the group?

 What do you think about the substitution of brass spacers for
needle bearings
 in this application?  I would think that the brass spacers would be less
 prone to failure than the needle bearings.

 Joe Graham

Brass spacers would not last unless they were provided with high
pressure oil.

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
 
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