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The Hurley seals I installed in 2001 (150 hrs) were
brand new. The are now very worn, there is a groove underneath the rubbing
service the entire length of each seal - so deep on some of the seals that
a ridge of metal has been pushed up along the top of the groove. This is
where the seal rubs against the top edge of the seal slot.
I recall that one of the supposed benefits of these seals is that the were
easier on rotor housings - (because they were softer?). Based on the
amount of wear after 150 hours I think an apex seal failure (in my engine) was
inevitable before 300 hrs (just speculation based on amount of seal
wear).
My personal opinion is a combination of softer
seals and worn apex grooves was my problem. If you have nice
vertical apex slots then there is almost no bending force on the seal and
the seal slides up and down in the slot supported by the wall. If
the apex groove is wider at the top (for whatever reason), there is a bending
motion imparted to the seal - the bottom of the slot is still at specs holding
the bottom of the apex seal in one plane, however when the combustion gases push
on the seal, the top portion of the seal is no longer supported (by
the top walls of the slot) in the same plane as the bottom. This
imparts a bend motion on the seal - being brittle it can not take much bending
motion before breaking - and all else follows.
On the other hand if you have a stronger seal and
one which withstand some bending motion. IF that is part of the failure process then the stronger seals will (in
my opinion) almost certainly delay the failure.
To answer your question about having a "handle on
where those? things had been", not certain exactly which "things" you are
referring to. My engine was a JSpec engine imported from Japan - it
was a turbo engine - who knows how easily or hard it had been
driven. However, since I used 9.7:1 high compression rotors, we know they
came out of a 89-91 NA 13B - I have no idea what shape that engine was
in.
NO, I did not check the apex seal slots - I
certainly would have - had I known then, what I know now {:>).
They "looked" fine and I was unaware of the "V" slot problem.
In fact, I dare say most of the subscribers (Lynn
and a few others excepted) to this list were unaware ot the "V" slot problem
until my "incident". So if there is any good that has come out of the
"incident", I think it is many more folks will check out the apex seal slot much
more carefully before putting them in an engine. Either you are
comfortably within specs, or you go the 3mm route or buy new rotors (expensive I
agree - but your butt is worth it).
Perhaps, as I have stated, it was just a
combination of factors (all converging at the same time) that caused my failure
- might not happen 1 time out 100. It certainly has not done anything but
convince me that the rotary engine can fail (as can all things mechanical) -
BUT, even then it will get you back safely - what more can you ask of an
mechanical thing?
Ed A
----- Original Message -----
Sent: Saturday, April 23, 2005 11:26
PM
Subject: [FlyRotary] Re: rotor and seal
wear was Re: All Parts have arrived, Whew!
Rusty and Ed got what - 100 hrs or so? Rusty's seals were worn, the
slots wallowed out beyond specs, Ed's slots wallowed out beyond specs,
etc. Granted both engines were built from cores, but didn't both
have a pretty good handle on "where those things had been"?
Hi
Jim,
Just need
to correct a few facts. My engine was all new. No used parts at
all. The apex slots in the rotors are still just like new, but
the Hurley apex seal was considerably worn on the sides. Maybe
the slots were too tight?
Rusty
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