X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4472429 for flyrotary@lancaironline.net; Sun, 19 Sep 2010 09:11:39 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=msteitle@gmail.com Received: by iwn8 with SMTP id 8so4511734iwn.25 for ; Sun, 19 Sep 2010 06:11:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=eG2mXYv13r//TsvbS7aBpq8PVlEAolfFJl0bAuQswbA=; b=PQzKBlv+6/et8EJZ56dGE3geZMS0xQszZoa/WkBw+R/G6UGRA6s9B11admFa7r46Td J1Xjw1ay088BFtuQuBjJHfMtKZGA15wPdC5rlnvD1okozRof4/Dy6JT6Wzx7Q09x9FtY CHrBeJj52vfZ7WIaJz4HlsJ2vh/f/Hpzld9Wc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=BqbHxSzE+rnyc9K5GMe8+wCreVNAmupDBPyci/JkMvw0jvtkf+517ON12bm+MyJ+uI Y/De3XcTnpWALSq8NVvoARff6cEOjC1odwjaZTI0Mm4EgV2Hgu9W7KIgqLTm17KmGTdf tleR/KV4pjhdKwV7KBdnlEamLirgFijsL7ufo= MIME-Version: 1.0 Received: by 10.231.155.206 with SMTP id t14mr8413539ibw.34.1284901863073; Sun, 19 Sep 2010 06:11:03 -0700 (PDT) Received: by 10.231.173.137 with HTTP; Sun, 19 Sep 2010 06:11:02 -0700 (PDT) In-Reply-To: References: Date: Sun, 19 Sep 2010 08:11:02 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Watch that psru oil seal From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0050450156781ea92304909c871b --0050450156781ea92304909c871b Content-Type: text/plain; charset=ISO-8859-1 Lynn, Thanks for confirming that a retainer is a wise thing to add. I sometimes over engineer things. But this is one place where a little extra engineering is prudent. Also, you're correct, this seal does not see 90-100 psi as it is in the pathway with the drainback line. So, it should only see a few psi at most. Mark On Sun, Sep 19, 2010 at 7:14 AM, wrote: > In a message dated 9/19/2010 5:41:35 A.M. Eastern Standard Time, > msteitle@gmail.com writes: > > Kelly, > > My custom adapter plate was built on a Bridgeport mill. The hole spacing > (and sizes) were obtained from a drawing for the actual RD-2C plate. Could > it be a thou or two oversize? I guess that's possible, but I don't think > so. The machinist that did the work is very meticulous. However, before > reassembly, I'll definitely check it to be sure. The bottom line is that > there is 90-100 psi trying to push it out of place. So, I feel that a > mechanical fastener is the only real way to guarantee that it stays put 100% > of the time. > > Mark > > Anything not positively retained in aircraft, will eventually fall off. > Garlock style lip seals will just barely hold back oil splash with little to > no pressure. You see Garlocks pressed into cavities that are cast or formed > with retaining lips at the end. Not into smooth bores. More than a few > pounds against a lip seal over heats the seal and fails the lip allowing a > leak. Note the oil drainback paths in the rotary, so seals see no pressure > even beside a main bearing other than from crank case gasses.. > > I had a weaver Brothers three section dry sump pump that had the pressure > section in the blind end of a casting so no high pressurized oil was exposed > to a seal of any kind. The drive shaft extended from the scavenge pump end, > so any pressure pulses would of minimal size against the Garlock seal > pressed into a smooth bore in the end plate. Each session the seal would be > found dancing along the shaft with oil dripping off of everything. A > competitor told me to retain the seal with a plate of some kind. Once that > very long weekend was over I did that with a plate and three little screws. > I replaced the single lip seal with 2 half width lip seals and the plate and > never had another problem. I also cut a tiny groove from the suction side of > the pump to the center of the shaft cavity. Oil drain-back to a lower > pressure area. > > Lip seals are the most freedom loving seals of all. If pressurized they > turn their lips inside out and leak on you. > > If you persist, they will escape the bore and dump your oil out on the > ground. They have been that way since the first day. Thought should be > expended on the release of crank case gasses. The street engine has a tiny > tube sticking out of the oil filler neck. This is way too small for > operation above about 3500 RPM. > > Lynn E. Hanover > --0050450156781ea92304909c871b Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lynn,=A0

Thanks for confirming that a retainer is a wise= thing to add. =A0I sometimes over engineer things. =A0But this is one plac= e where a little extra engineering is prudent.

Als= o, you're correct, this seal does not see 90-100 psi as it is in the pa= thway with the drainback line. =A0So, it should only see a few psi at most.= =A0

Mark

On Sun, Sep 19, = 2010 at 7:14 AM, <Lehanover@aol.com> wrote:
=A0
I had a weaver Brothers three section dry sump pump that had the press= ure=20 section in=A0the blind end of a casting so no high pressurized oil was=20 exposed to a seal of any kind. The drive shaft extended from the scavenge p= ump=20 end, so any pressure pulses would of minimal size=A0against the Garlock sea= l=20 pressed into a smooth bore in the end plate. Each session the seal would be= =20 found dancing along the shaft with oil dripping off of everything. A compet= itor=20 told me to retain the seal with a plate of some kind. Once that very long= =20 weekend was over I did that with a plate and three little screws. I replace= d the=20 single lip seal=A0with 2 half width lip seals and the plate and never had= =20 another problem. I also cut a tiny groove from the suction side of the pump= to=20 the center of the shaft cavity. Oil drain-back to a lower pressure=20 area.=A0
=A0
Lip seals are the most freedom loving seals of all. If pressurized the= y=20 turn their lips inside out and leak on you.
=A0
If you persist, they will escape the bore and dump your oil out on the= =20 ground. They have been that way since the first day. Thought should be expe= nded=20 on the release of crank case gasses. The street engine has a tiny tube stic= king=20 out of the oil filler neck. This is way too small for operation above about= 3500=20 RPM.
=A0
Lynn E. Hanover

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