Hi Paul, we meet briefly a couple years ago at OSH. I have about 250
hr. of
flying on my project and a new web page at www.netlynx.us/sahobby I
broke
my Ross redrive a year ago and I'm looking for some inspiration to
get back
to it. Thanks Mark Kirkpatrick
What part broke?
Paul Lamar ...No rotor no motor.
I would use it for a boat anchor and go buy one of Tracy's.
Ken
I love those nice Ross castings. The Ross is the lightest
box around. I would dial indicate the ring gear for run out
and if that was OK I would fix it. It has too many bearings.
All you need is the self centering sun gear and the e-shaft
pilot. Planetary are intrinsically self centering on the ring
gear and that is how the loads on the gears [teeth] are equalized,
If you are throwing it away I'll pay shipping.
---------------------------------------------------------
A 20B in and of it self, I maintain, does not have enough
torque to break a Ford four pinion planetary gear set.
The 20B torque is 240 ft pounds max. To prove it set the planetary
up on a bench. Lock the ring gear in place. restrain
the planet carrier from rotating. Allow it to float.
I am willing to bet $100 it won't fail with 1000 foot
pounds of pure torque applied to the floating sun gear.
These planet sets are used with V8 engines that have 400 foot
pounds of torque behind followed by a torque converter that is
putting out about 600 foot pounds or more.
Notice the discoloration the bearing forward of the sun gear.
Perhaps this was putting enough heat into the sun gear to
weaken it. That is one scenario. That is in addition concentricity
problems. Another is the clutch disk used by Ross could be a factor.
Tracy uses a rubber coupling. Vance used to tell me he knew of an
English engineer that was fond of saying: "An ounce of rubber is
worth a pound of engineering" :)
Paul Lamar ...No rotor no motor.
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Paul,
Maybe. But, when the Rosses were actively selling these drives there
was a 6-pinion model and a 6-pinion retro-fit available. The 6-pinion
gear set was the recommended option for 20B installations. Tracy also
recommends his 6-pinion model for the 20B. Although the peak torque in
the automobile could be higher, the average torque is much less than an
aircraft installation. In the automobile the rotational speed is also
much less. The sun gear is the main shaft in the transmission and is
turning at highway speeds around 2000 RPM or less.
Aubrey Thompson
All true. And I am not recommending the four pinion for the 20B.
I just find it strange that the four pinion failed so soon.
BTW back in the days the Ford planetary 1960's was designed the
high way RPMs were more like 4000 RPM. Drag racing engines
used the four pinion Ford and some of the engines had six or
seven hundred HP.
The six pinion, as far as the Ford planetary is concerned, was actually
invented by an after market drag racing transmission builder prior
to the time Ford introduced it around 2001.
http://www.performanceautomatic.com/transc6.htm
I myself was considering it in 1998 and John Moran
actually built one for us around 2000 as I recall.
Paul Lamar ...No rotor no motor.
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