X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 12 Feb 2008 14:40:18 -0500 Message-ID: X-Original-Return-Path: Received: from web54410.mail.yahoo.com ([206.190.49.140] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with SMTP id 2726397 for lml@lancaironline.net; Tue, 12 Feb 2008 10:47:53 -0500 Received: (qmail 11156 invoked by uid 60001); 12 Feb 2008 15:47:52 -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=dGQQGKTSbcjEUuoJXAZjJf0zQ9EVZ/ih+UZed2R7eDnzV3kgz1oIJfOkpaUg8v1yXckFhUlhJCciZq0baoJ64+aPzkaakOkn9EwEVD7MsoQcOm29d+/PvFpqhtx+u7kXV4QMaZUnxJawQAJIdpw7MZGemYhLvSmp4llGhJj2KdE=; X-YMail-OSG: GF4y1MAVM1nMO5cPif5ZEg4Smhls0pww1ne4Rf9LzfAdNdcyllJa6k_gfsdstMa0BA-- Received: from [76.8.220.18] by web54410.mail.yahoo.com via HTTP; Tue, 12 Feb 2008 07:47:52 PST X-Original-Date: Tue, 12 Feb 2008 07:47:52 -0800 (PST) From: randy snarr Subject: Re: [LML] 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="0-1326276928-1202831272=:7415" Content-Transfer-Encoding: 8bit X-Original-Message-ID: <679665.7415.qm@web54410.mail.yahoo.com> --0-1326276928-1202831272=:7415 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Good thought Larry, If you open the dump valve now and move the gear up and down you create negative pressure from side to side. If the system had access to a line with air in it, it would pull it into the system. If you just crack the valve to release positive pressure you are exactly right. You are also right if the vent line is run to the resevoir and submerged it would just pull a little fluid from there. I thought of adding a restrictor with a tiny pin hole between the 3way and the resevoir. I may just put a check valve to allow only one way travel on the vent line. I found them at mcmastercarr and they are cheap. Around $10 or so. I will post my finding on the LML once I have completed whatever it is I am going to do... Thanks for the input!!! Randy... LHenney wrote: v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Randy, I’m not getting this concern. The dump line goes to the tank and ends submerged in fluid with a ¼” down tube in the reservoir. Additionally, in my opinion no fluid would ever travel upstream toward the valve. Thus, no air would be added to the system by use of a 3 way vavle. Larry --------------------------------- From: randy snarr [mailto:randylsnarr@yahoo.com] Sent: Sunday, February 10, 2008 9:59 PM To: lml@lancaironline.net Subject: Re: [LML] Re: 235/320/360 gear dump valve idea 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. --------------------------------- Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. --0-1326276928-1202831272=:7415 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Good thought Larry,
If you open the dump valve now and move the gear up and down you create negative pressure from side to side. If the system had access to a line with air in it, it would pull it into the system. If you just crack the valve to release positive pressure you are exactly right. You are also right if the vent line is run to the resevoir and submerged it would just pull a little fluid from there. I thought of adding a restrictor with a tiny pin hole between the 3way and the resevoir. I may just put a check valve to allow only one way travel on the vent line. I found them at mcmastercarr and they are cheap. Around $10 or so.
I will post my finding on the LML once I have completed whatever it is I am going to do...

Thanks for the input!!!

Randy...

LHenney <LHenney@charter.net> wrote:
Randy,
 
I’m not getting this concern.  The dump line goes to the tank and ends submerged in fluid with a ¼” down tube in the reservoir.  Additionally, in my opinion no fluid would ever travel upstream toward the valve.  Thus, no air would be added to the system by use of a 3 way vavle.
 
Larry
 
From: randy snarr [mailto:randylsnarr@yahoo.com]
Sent: Sunday, February 10, 2008 9:59 PM
To: lml@lancaironline.net
Subject: Re: [LML] Re: 235/320/360 gear dump valve idea
 
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
 
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.

Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. --0-1326276928-1202831272=:7415--