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 bay0-omc3-s35.bay0.hotmail.com ([65.54.246.235] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with ESMTP id 2722860 for lml@lancaironline.net; Sat, 09 Feb 2008 20:23:19 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.235; envelope-from=randystuart@hotmail.com Received: from hotmail.com ([65.55.139.26]) by bay0-omc3-s35.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Sat, 9 Feb 2008 17:22:41 -0800 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sat, 9 Feb 2008 17:22:40 -0800 X-Original-Message-ID: Received: from 68.183.63.181 by BAY134-DAV16.phx.gbl with DAV; Sun, 10 Feb 2008 01:22:37 +0000 X-Originating-IP: [68.183.63.181] X-Originating-Email: [randystuart@hotmail.com] X-Sender: randystuart@hotmail.com From: "Randy" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: 235/320/360 gear dump valve idea X-Original-Date: Sat, 9 Feb 2008 17:22:36 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0038_01C86B40.5CE6FCE0" 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-OriginalArrivalTime: 10 Feb 2008 01:22:40.0558 (UTC) FILETIME=[6DB5D4E0:01C86B83] X-Original-Return-Path: randystuart@hotmail.com This is a multi-part message in MIME format. ------=_NextPart_000_0038_01C86B40.5CE6FCE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I don't know if all the pumps are the same internally through the years. = I did have an older one with the metal reservoir and now I have a new = one with the plastic reservoir. They both did the some thing in warmer = temps.=20 These pumps were not made for aircraft, they are marine pumps, used for = lifting in/out drives on boats. They work great in our planes and create = plenty of pressure to do the job but a boat hydraulic system is not set = up the same as our little airplanes. The in/out drive system doesn't use = or require any pressure sensing switches. The pump either pushes the = drive up or down depending on the direction of the fluid flow. When it = gets to the end it just opens the preset pressure release valves inside = the pump and flows the fluid back into the reservoir. Our system needs = the pressure sensing switches so the landing gear will stay pressurized = either up or down.=20 So, the shuttle valve ( Spool Valve ) in these pumps have no need to = allow a path for the fluid to return to the reservoir, unless it is = running. The pump can be opened and modified to stop the valve from = closing so easily but I don't know what other effect this might have on = the functions of the pump to hold the pressures. Might be better to = externally solve this problem.=20 A T-shuttle valve can be had from ebay or Lancair parts. They sell them = for about $20 and I bought some on ebay for $4.=20 It's all about experimental...........=20 Randy Stuart LNC-2 ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Saturday, February 09, 2008 3:43 PM Subject: [LML] Re: 235/320/360 gear dump valve idea <> 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=20 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. ------=_NextPart_000_0038_01C86B40.5CE6FCE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I don't know if = all the pumps=20 are the same internally through the years. I did have an older one with = the=20 metal reservoir and now I have a new one with the plastic reservoir. = They both=20 did the some thing in warmer temps.
These pumps = were not made=20 for aircraft, they are marine pumps, used for lifting in/out drives on = boats.=20 They work great in our planes and create plenty of pressure to do the = job but a=20 boat hydraulic system is not set up the same as our little airplanes. = The in/out=20 drive system doesn't use or require any pressure sensing switches. The = pump=20 either pushes the drive up or down depending on the direction of the = fluid flow.=20 When it gets to the end it just opens the preset pressure release valves = inside=20 the pump and flows the fluid back into the reservoir. Our system needs = the=20 pressure sensing switches so the landing gear will stay = pressurized=20 either up or down.
So, the shuttle = valve ( Spool=20 Valve ) in these pumps have no need to allow a path for the fluid to = return to=20 the reservoir, unless it is running. The pump can be opened and modified = to stop=20 the valve from closing so easily but I don't know what other effect this = might=20 have on the functions of the pump to hold the pressures. Might be better = to=20 externally solve this problem.
A T-shuttle valve = can be had=20 from ebay or Lancair parts. They sell them for about $20 and I bought = some on=20 ebay for $4.
It's all about=20 experimental...........
 
Randy=20 Stuart
LNC-2
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Saturday, February 09, = 2008 3:43=20 PM
Subject: [LML] Re: 235/320/360 = gear dump=20 valve idea

<<From:=20 Randy <randystuart Then the pump pressurizes the high side = and it=20 stops, and the shuttle valve = centers,...>> This=20 is where pumps in the fleet differ.  In my two pumps the shuttle = valve=20 does not return to center.  It stays where the fluid last pushed=20 it.  The O-ring on the spool offers up much more friction than = the spring=20 on the poppet valve could ever hope to overcome.  I am curious if = all=20 pump vintages have O-rings on the spool valve and/or how snug the fit = might=20 be?  If the spool can be made to stay put, the problem goes=20 away.  I am simply suggesting this as something to investigate = before=20 a lot of new plumbing is added to the system.   A=20 little over a year ago, when this issue was last discussed, I took a = series of=20 photos showing the effect of heating and cooling.  What is = observed is=20 that the high side pressure goes up and down with temperature (heat = gun and=20 ice bath) while the low side remains at zero.  http://www.= n91cz.com/Hydraulics/Heat_Cool_Series.doc  My=20 pumps are '95 and newer.   Chris=20 Zavatson N91CZ 360std www.N91CZ.com


Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try=20 it now. ------=_NextPart_000_0038_01C86B40.5CE6FCE0--