Mailing List lml@lancaironline.net Message #44756
From: Zavatson, Christopher J (US SSA) <Christopher.Zavatson@baesystems.com>
Sender: <marv@lancaironline.net>
Subject: RE: [LML] Re: LNC2 Hyd Chirp Tim/ Joe/ Brent Question
Date: Tue, 06 Nov 2007 21:18:06 -0500
To: <lml@lancaironline.net>
Randy,
The next thought experiment might by to ask whether or not your (and Lorn's) spool valve is returning to center for some reason after pump shut down.  That would allow pressure to build in the low and high sides simultaneously.  Generally it takes quite a bit of force to move the spool valve around.  The O-ring provides a lot of friction.  Two things are obvious though.  First, the valve is working properly while the pump is running since you (and Lorn again) see zero pressure on the low side.  The second constant is that when the pump is not running and actively pushing the spool valve against the poppet valve, your systems are sealing themselves up.  If your spool valve had very little or no friction I could see this happening.  The poppet valve does have a very light spring to help close it when not subjected to any other forces.
This video was posted previously.  It shows the system responding to an intentional leak from high to low.  The pump cycles repeatedly without affecting the low side pressure reading.
Randy, the answer is out there........somewhere.
Chris
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