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Straight PTFE has a Durometer 50D-65D. I'll go with it. https://www.mcmaster.com/9266K82/Prop I have is a 74" ground adjustable Sensenich. Pitched to 22degrees. Static full power is 2200 while flying is 2600. With the 3.17 gearing, engine RPM is 8250. Finn, I'm not sure, the restrictor is part of the fitting. Neil, can you pipe in here? I won't say I know anything like Tracy and them do, but a planetary gear, doesn't it only need a splash of oil for lub?
Does 'glass filled' mean fiberglass?
Any abrasive risk if the PTFE does start to wear? Looks like they
also have straight PTFE sheet stock, but I didn't look at
durometer.
Are you running some monster 8' diameter prop with that ratio?
Charlie
On 4/28/2021 5:46 PM, Matt Boiteau mattboiteau@gmail.com wrote:
Squished / deformed is the verbage I used back in
2019 about it. I can't seem to find any pictures on it, but I
remember it being deformed up pretty good. I've been
battling issues in the past with the vulcanization rubber of
Neil's cushion drive was coming apart. I've put on Tracey's
Cushion drive in the meanwhile.
Dry fitting everything (no oring and no snubber) with the input
shaft sitting all the way down on the prop shaft, I have 0.085"
clearance. To get the 5-10thou gap, I would need a snubber
0.075" - 0.080" thick. The closest I can get is 1/16" thick,
which is 0.0625.
There is a restrictor in the fitting going into the PSRU. I
have a temp gauge on the PSRU, and it stays consistent with
the oil. I have parts to add a PSI sensor to the back half of
the PSRU to see if things are draining okay.
The
confusing thing to me is how it got hot enough to melt
nylon; over 400 degrees F. That seems a lot hotter than
than the shaft or bearings should ever get.
The end play was good. Metal ruler across and could
just see daylight across.
Neil's uses a rubber oring, so we test
endplay without it. Then adding the oring will add the
nessessary clearance in end play.
The one Neil supplied was either nylon
or Teflon flat washer and it melted, so removed it. So
talking with him, switched it out to the oil embedded
one. Again, just a flat washer.
Anyone have more details what Tracey
used? Like a spring washer made out of nylon?
Too little or too much end play?
Tracy specifies 0.005 to 0.035"
Note that if you check it without RTV, it may
increase when you assemble it.
Finn
On 4/28/2021 1:05 PM, Matt Boiteau mattboiteau@gmail.com
wrote:
I have one of Neil's 3.17 psru
with Tracey's cushion drive. *I also sent
Neil an email but it's late in the night in
Australia.
After my fly off hours,
tearing down the plane to inspect
everything. The Ultra-Low-Friction
Oil-Embedded Thrust Bearing is broken into
pieces.
https://wwwmcmaster.com/7421K28/
The nylon or teflon washer supplied just
melted. I thought I nailed it with a fix
using the oil-embedded, but I guess not.
I think in Tracey's documentation, he
called it a snubber ? Any ideas what I can
use, or why this happens?
--
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