X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 09 Feb 2008 18:43:10 -0500 Message-ID: X-Original-Return-Path: Received: from web36903.mail.mud.yahoo.com ([209.191.85.71] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with SMTP id 2722046 for lml@lancaironline.net; Sat, 09 Feb 2008 02:57:17 -0500 Received: (qmail 79344 invoked by uid 60001); 9 Feb 2008 07:57:17 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type:Message-ID; b=rpYyI1OBl4ididE7ZAUnZrPMLr+aW0w6kBJaRIk9FjeF92XXCBBt/QlYkctcdB+eFJmYVECe0gS7Knw+MLw9N6TN6pp1ppk8cSd6gk/23iWOl7WO8rKaTHm52LkQ8odCsQFkhQcw8boeODic/kcYm11k5BtnKxSNK7aukDT6GiU=; X-YMail-OSG: RVeQ4tUVM1nLUq9LwSPBt.wXmrAcL_FWqLzfAppQ3PNJlt_3KneyoyBxuPAUreFuQtU8ufHO.yMM60m6DW2p_uVYlnWX0hmBwI2281YsMJRqCrk- Received: from [76.246.62.146] by web36903.mail.mud.yahoo.com via HTTP; Fri, 08 Feb 2008 23:57:17 PST X-Mailer: YahooMailRC/818.31 YahooMailWebService/0.7.162 X-Original-Date: Fri, 8 Feb 2008 23:57:17 -0800 (PST) From: Chris Zavatson Subject: Re: [LML] Re: 235/320/360 gear dump valve idea X-Original-To: Lancair Mailing List MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1246502407-1202543837=:72909" X-Original-Message-ID: <598576.72909.qm@web36903.mail.mud.yahoo.com> --0-1246502407-1202543837=:72909 Content-Type: text/plain; charset=us-ascii <> 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 ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs --0-1246502407-1202543837=:72909 Content-Type: text/html; charset=us-ascii
<<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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