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...