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Date: Wed, 13 Dec 2000 12:56:15 -0800
To: lancair.list@olsusa.com
From: "Mike S. Reinath" <mreinath@mail.arc.nasa.gov>
Subject: Hydraulic Pump
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Ed writes:
...  I'm told that the pump manufacturer has a fix that will make sure
the unpressurized circuit vents to atmosphere preventing this problem.


I put pressure gauges in the low and high lines also. I have noticed 
that the low side does not vent to zero as quickly as the high side. 
In fact, when I raise the gear, the low pressure actually increases 
for a short time as the gear is going up. I have my low-pressure 
switch set to about 500 psi. During the up cycle, the low pressure 
will climb to about 650 to 700 psi before it starts to drop. The 
pressure eventually gets to zero, but it takes about a minute. In 
order to prevent the pump from cycling on and off during the up 
cycle, I have to set my high-pressure switch to about 1200 psi. I am 
sure I could get by with a much lower setting if the low-side 
pressure would vent faster. The high side vents to zero immediately 
when I lower the gear.

Has anyone else noticed this behavior? Does the fix Ed writes about 
fix this problem?

Mike Reinath
360 MKII Std. build 94%
N3602M
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