X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 10 Feb 2008 22:58:37 -0500 Message-ID: X-Original-Return-Path: Received: from web54405.mail.yahoo.com ([206.190.49.135] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with SMTP id 2723537 for lml@lancaironline.net; Sun, 10 Feb 2008 12:49:57 -0500 Received: (qmail 91147 invoked by uid 60001); 10 Feb 2008 17:49:56 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=oyVyN81uXFKWL6GJfvIlGgvNlxxCYXBpNuLyHvOM+ckgKspuY5hYyA88tbXldqG0cDWXokEGACNHtxVJktDjZjy8bGOLZhsRicb473Xk/yOVat1Yc6FP9Kh+4T9DrXsQK2Up6goTFhwNZmPyExEC7ftTx4pEc4Ff7+X4QDXPKY4=; X-YMail-OSG: R7da48IVM1luThY6qS.FAEZ2ZEnAYu5OL3TXi.2lZogyfPmn35kE2XcIzxA6c.2wH7eg5Y496Qz7cXeU6SB79FBnpHln1XJj_falL7_T6Q7sQVdiiW_LQ4fuXmIOM5AYycfOXuzz3PKNLTm1h6xuDIKdyA-- Received: from [76.8.220.18] by web54405.mail.yahoo.com via HTTP; Sun, 10 Feb 2008 09:49:56 PST X-Original-Date: Sun, 10 Feb 2008 09:49:56 -0800 (PST) From: randy snarr Subject: Re: [LML] Re: 235/320/360 gear dump valve idea X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1197320105-1202665796=:88277" Content-Transfer-Encoding: 8bit X-Original-Message-ID: <599636.88277.qm@web54405.mail.yahoo.com> --0-1197320105-1202665796=:88277 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Chris, Is there such a thing as a check valve that could be incorporated into the 3rd pressure dump line to the hyd reservoir? That way you could open the dump valve releasing positive pressure from the high/low sides of the system but you would not be allowing air from that same line if the was no positive pressure or negative pressure? Could a shuttle valve help do that? Randy Snarr Chris Zavatson wrote: <> This is where pumps in the fleet differ. In my two pumps the shuttle valve does not return to center. It stays where the fluid last pushed it. The O-ring on the spool offers up much more friction than the spring on the poppet valve could ever hope to overcome. I am curious if all pump vintages have O-rings on the spool valve and/or how snug the fit might be? If the spool can be made to stay put, the problem goes away. I am simply suggesting this as something to investigate before a lot of new plumbing is added to the system. A little over a year ago, when this issue was last discussed, I took a series of photos showing the effect of heating and cooling. What is observed is that the high side pressure goes up and down with temperature (heat gun and ice bath) while the low side remains at zero. http://www.n91cz.com/Hydraulics/Heat_Cool_Series.doc My pumps are '95 and newer. Chris Zavatson N91CZ 360std www.N91CZ.com --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. --------------------------------- Looking for last minute shopping deals? Find them fast with Yahoo! Search. --0-1197320105-1202665796=:88277 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Chris,
Is there such a thing as a check valve that could be incorporated into the 3rd pressure dump line to the hyd reservoir?
That way you could open the dump valve releasing positive pressure from the high/low sides of the system but you would not be allowing air from that same line if the was no positive pressure or negative pressure?
Could a shuttle valve help do that?

Randy Snarr

Chris Zavatson <chris_zavatson@yahoo.com> wrote:
<<From: Randy <randystuart
Then the pump pressurizes the high side and it stops, and the shuttle valve centers,...>>
This is where pumps in the fleet differ.  In my two pumps the shuttle valve does not return to center.  It stays where the fluid last pushed it.  The O-ring on the spool offers up much more friction than the spring on the poppet valve could ever hope to overcome.  I am curious if all pump vintages have O-rings on the spool valve and/or how snug the fit might be?  If the spool can be made to stay put, the problem goes away.  I am simply suggesting this as something to investigate before a lot of new plumbing is added to the system.
 
A little over a year ago, when this issue was last discussed, I took a series of photos showing the effect of heating and cooling.  What is observed is that the high side pressure goes up and down with temperature (heat gun and ice bath) while the low side remains at zero. 
My pumps are '95 and newer.
 
Chris Zavatson
N91CZ
360std

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