X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 02 Nov 2007 15:09:02 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-banded.atl.sa.earthlink.net ([209.86.89.70] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2452394 for lml@lancaironline.net; Fri, 02 Nov 2007 13:38:07 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.70; envelope-from=leighton@teleport.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=teleport.com; b=DcpiPR3YtYOa8F4fdW14ykDRhBgZhnb4hkoOf+C7MPv8qlzt6rKyU7cFz6PdQINa; h=Received:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [4.242.171.215] (helo=user) by elasmtp-banded.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1Io0SW-0006S1-Kb for lml@lancaironline.net; Fri, 02 Nov 2007 13:37:29 -0400 X-Original-Message-ID: <000901c81d77$0a871dc0$d7abf204@user> From: "Leighton" X-Original-To: "Lancair Mail list" Subject: Hydraulic cylinder leaks X-Original-Date: Fri, 2 Nov 2007 10:37:27 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C81D3C.5CE8C0E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-ELNK-Trace: ea0fe3d44b30ba0fc355332e9c4b49d598c48853aa0a5d892fdb7e916d8955ebf08e082bdc90425e350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 4.242.171.215 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C81D3C.5CE8C0E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The recent discussion of leaking Lancair hydraulic cylinders caused me = to reminisce about my time spent in fluid power component sales and got = me to dust off some old cylinder catalogs. Most, if not all, hydraulic = cylinder manufactures of the type we use offer several levels of quality = and at the bottom of the list are the lowest price and lightest duty = ones that utilize o-rings for all the seals. The higher quality = versions use u-cup seals on the pistons and where the rod exits the = barrel and usually a rod wiper to keep wear-inducing particles from = getting to the rod seals. U-cup seals are V shaped with the open side = toward the pressure source. A double acting cylinder, like the ones we = use, have two on the piston, one facing each direction. It doesn't take = much imagination to see how this arrangement will greatly prolong = internal leakage across the piston. They also have a lower breakaway = force than an o-ring seal because they are self-energizing and don't = rely on an interference fit to seal. I would challenge anyone on the = list who is adept at web searching to see if cylinders with the good = seals can be found that have the same external dimensions. Cylinder = manufactures commonly do special dimension cylinders at very little = extra cost. What we're asking for are double acting hydraulic cylinders = with u-cup seals (some might have a different term for them) that can be = supplied dimensionally interchangeable to the ones we are using now. = You might also be surprised how relatively inexpensive these will be. =20 Leighton Mangels ------=_NextPart_000_0006_01C81D3C.5CE8C0E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The recent discussion of leaking Lancair = hydraulic=20 cylinders caused me to reminisce about my time spent in fluid power = component=20 sales and got me to dust off some old cylinder catalogs.  Most, if = not all,=20 hydraulic cylinder manufactures of the type we use offer several levels = of=20 quality and at the bottom of the list are the lowest price and lightest = duty=20 ones that utilize o-rings for all the seals.  The higher quality = versions=20 use u-cup seals on the pistons and where the rod exits the barrel and = usually a=20 rod wiper to keep wear-inducing particles from getting to the rod = seals. =20 U-cup seals are V shaped with the open side toward the pressure = source.  A=20 double acting cylinder, like the ones we use, have two on the piston, = one facing=20 each direction.  It doesn't take much imagination to see how this=20 arrangement will greatly prolong internal leakage across the = piston.  They=20 also have a lower breakaway force than an o-ring seal because they are=20 self-energizing and don't rely on an interference fit to seal.  I = would=20 challenge anyone on the list who is adept at web searching to see if = cylinders=20 with the good seals can be found that have the same external = dimensions. =20 Cylinder manufactures commonly do special dimension cylinders at very = little=20 extra cost.  What we're asking for are double acting hydraulic = cylinders=20 with u-cup seals (some might have a different term for them) that can be = supplied dimensionally interchangeable to the ones we are using = now.  You=20 might also be surprised how relatively inexpensive these will be. =20
 
Leighton Mangels
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