Finn Lassen wrote:

Here's some pictures of the Ross drive fix:

1/4" thrust plate screwed to front of bulkhead, holding oil seal in
place.

Rear side of bulkhead with 3568 seal visible.

Thrust bearing. Also new lubrication line (1/16 teflon line) barely
visible, sprays directly onto sun gear. Also tiny hole in line

spraying

onto thrust plate, hopefully lubricating thrust bearing.

Planet carrier showing added oil line.

Redrive mounted, showing temporary nylon line. I didn't feel there

was

room for an 1/8" NPT fitting, so I drilled and tapped 10-32 holes,

and

drilled small holes through cut off AN3 bolts. I don't trust a hose

to

stay on these stubs. The temporary nylon line shown broke during the
first test flight. By the time I'd landed and taxied to my tiedown

spot,

"Low oil" light lit, I could only drain less than 1 quart, which

means I

sprayed some 5 quarts over the neighborhood (mosquito control).
Interestingly, oil pressure stayed up while I was loosing oil. If
anybody can direct me to a source for less than 1/8" NPT fittings,
please let me know. Jim Mosur?

The new sun gear was cut to a length (approx 1.25") allowing for

thrust

bearing and thrust plate. Tracy felt that no pin was needed to hold

the

sun gear. During static run-ups and test flights I noticed no

slippage.

The "lip" on the forward side of the bulkhead was machined down

(approx

3/16") to make space for the thicker 1/4" thrust plate.

Finn

What kind of camera did you use to take those pictures Finn?

I guess we are about to find out just how long a single needle thrust
bearing will last with Finn's HP level, a 2.17:1 Ross box  and at 6000
RPM  :-)

Paul Lamar

While working on Finn's Ross drive I saw just how variable the

workmanship

on them is.  Absolutely NOTHING on it was concentric.  By comparison,

the

Ross I used to fly was a beauty!  It also finally dawned on me why I got

a

bad feeling about Finn's drive when I first checked the system lash (a
couple of years ago).  It was the tightest Ross drive I've ever checked.

The

lash at the prop tip varied from about 3/16 to almost zero.  This may

sound

good at first but it should be remembered that a planetary gear set has
maximum gear lash when it is in perfect alignment.  The worse the

alignment

is, the lower the gear lash.  The really bad side effect is that this

tends

to concentrate the load on a single planet gear.

After Finn reassembled his drive, the gear lash was higher and more
consistent in all positions.  I'm looking forward to seeing what it
looks  like in 10 - 25 hours.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

I am relived that you are on the job Tracy :-) Thanks.

Paul Lamar

I would just like to compliment Tracy on RD1.  I just received it on Friday.
It is a beautiful piece of work.

Ken Gillanders

 
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