Hello All,

Here?s a question about the ROSS PSRU, I?ve gotten many good suggestions
on modifying and adding thrust bearings to prevent the input shaft from
rocking back and forth.  There?s one thing that keeps nagging at my
mind; I remember reading somewhere a fellow had a ROSS PSRU (no mods) on
a gyro and he was able to put over a thousand hours on his unit without
any troubles.  Now a gyro is a pusher, and my plane is a pusher (Osprey
2) ? would I have the same luck on my ROSS PSRU?  Or should I bite the
bullet and do the modifications to my gear box?

Cheers,

Burck

Good question. I assume you have a 2.17:1. The planet carrier is fixed
to the housing so the prop shaft is pushing on the planet carrier and not
the sun gear. The sun gear tends to un screw it self and that is why
it puts a load on the e-shaft and then on the e-shaft thrust bearing at
the front of the engine. I have no idea how the guy lucked out
with a thousand hours. Perhaps he did not have as much HP as Tracy had.

IMHO you still need that thrust bearing.
-- 
Paul Lamar ...No rotor no motor.

Burck and Paul...

My "testosterone" gyroplane didn't have a thrust bearing in it's 2.85:1
Ross.  My *significantly* bridgeported 12a was making 219 hp at 7800 rpm on
the dyno (as I remember).  I routinely ran it at 7500 rpm for WOT, and
"throttled back" to 6000-6300 for my "regular" (read as: abusive) flight
activities.  I had over 1100 hours, sold it (the PSRU) to another pilot, and
he put another 100'ish hours on his machine before selling it yet again...
don't know it's current history though.   I obviously got lucky!!!  On an
email to Tracy long ago... he indicated his experience was that the 2.85:1
had a different wear pattern than the 2.17:1 system.

Yet I'd agree that the thrust bearing is a safety necessity for any future
build I perform.   Again... I obviously got lucky!!

Gary Buster
Tyler Texas
N263GB

You sure did. The stock Mazda thrust bearing is designed to take
the occasional force from the clutch throw out mechanism.
A far cry from 700 pounds. Perry Mick has some experience along these
lines as well. He flew a direct drive ducted fan for a few years
and then changed the front cover and thrust bearing when it showed
signs of failing for a larger 3rd gen version.

The 2.85 has a larger sun gear so that reduces the helical gear
thrust load according to the attached equation.

Paul Lamar ...No rotor no motor.

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