Randy,
Hold off on the
machine work. Your pump is designed with a third port (between the two
now in use). It is threaded and ready for your return line. A ¼ “
tubing can be installed as a down tube in the tank (mine came with the tube
installed).
Also, Randy Stuarts
idea of a T shuttle sounds very, very interesting. I don’t completely
know what a T shuttle valve is however. Thus, I’m grappling with check
valve analogies and getting a lot of “how would that work?” thoughts.
Does this mean pressure on up circuit triggers opening of shuttle
from down circuit, therefore T goes to third port??? I’m tempted to like
this idea. Additionally, could second T also tie in to third port and
allow 3 way dump common path to reservoir. Please tell us more R.
Stuart…..
Larry
Henney
N360LH
Much less chirping
lately after changing out pump O rings; Lancair also got more pressure gauges
in stock and shipped mine.
From:
Sky2high@aol.com [mailto:Sky2high@aol.com]
Sent: Wednesday, February 06, 2008 2:49
PM
To:
lml@lancaironline.net
Subject: Re: [LML] 235/320/360 gear dump
valve idea
Remember that the
reservoir needs a small vent hole so that air pressure or vacuum does not
build up in the reservoir itself. Usually the vent is in the filler cap
or its threads.
Scott Krueger AKA
Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL
(KARR)
Pilot not TSO'd, Certificated score only >
70%.
In a message dated
2/6/2008 11:29:13 A.M. Central Standard Time, randylsnarr@yahoo.com
writes:
With the way the
hydraulic system is currently designed, you equalize the pressure on the
high and low sides when it is opened. For those of us who have pressure
gauges, you can see that you can have significant pressure on the system
even when the valve is opened. I want to be able to not only equalize the
pressure between the high and low sides of the hydraulic system with the
dump valve but also release the pressure on both sides.
Today I
purchased a 3 way valve to do just that. The idea is to open the
valve connecting the high and low sides and also releasing the
pressure back to the tank.
I will most likely run a low pressure line
like nylaflow back to the pump and make spin up a custom fitting on the
lathe out of aluminum to go into the dipstick hole and terminate the return
line there. I will make a needle dipstick checker that will screw into the
same fitting for checking fluid level.
If you wanted to do it the easy
way, you could always just dump the low pressure line out the belly of the
airplane onto the ground. It would take very little fluid to drop the
pressure and there would be no need to deal with connecting the low pressure
fluid line to the tank.
I hate pulling the airplane out of a cool
hanger into the warm sunshine and watching the gear pressures rise to 6-700
lbs before the master switch is turned on! We all know what happens when
they hit 900. Yep no gear retraction as the upper limit has been tripped by
the system pressure.
My new valve would fix that!!!
I
hope...