Bryan, Gary, Randy S’s.,
Bryan, yes the ball
and spring get chunked.
Gary, I’m
incompetent at computer sketching but it is a one liner. Perhaps S.Kruger
could help me. My thought is that a 3 way dump valve will directly
replace the existing dump valve. As far as the sketch is concerned, I
would draw a line from the new dump valve to the center port of my pump.
A piece of plane ole ¼” tubing slips in the pump and down to near the reservoir
bottom.
A possible option for the dump valve is :
3-Way Gear Dump Valve
Long Beach Valve and Fitting
3940 Gilman St
Long Beach, CA 90815
(562) 494-6694
(562) 494-0493 fax
Part Number: B-42XHS4-BKB
HOWEVER: this whole 3 way dump valve may just be a feel good
solution. In the final analysis it may be just fine as far as
safety of gear extension (electric or freefall) is concerned. So far
there have been no indications that anyone’s gear has hesitated to come down
after cracking the dump valve (in it’s existing design). As I mentioned
one other time, the loss of the physical handle combined with the unique high
to low pressure bleeding could pose a problem.
AND: Randy Stuarts external T shuttle sounds to be an elegant
and simple correction for the quirk which would preclude the need for the 3 way
valve. Have you got a vendor and part that you are considering?
We’d love the data. Do the 2 ends of the T go High and low pressure connections
and the third leg directly to the pump return port?
Disclaimer: The above discussion is from a list of things I’m
trying to get accomplished on my speeder. I have not done any of the
aforementioned projects to my plane (weight penalty, budget, time, honey do’s, etc).
I haven’t even got the darn gages installed which have been sitting in my
hangar for a week. I do appreciate the feedback from those with more time
on there hands.
Did anybody notice that Bruce Hammers transcontinental speed record
of Mar 06 got walloped by a blistering 30 mph. New record 288 mph by a
Questair Venture! Say it isn’t so……..
Larry
Very Prompt Lancair 360LH
From:
Bryan Wullner [mailto:vonjet@gmail.com]
Sent: Friday, February 08, 2008
2:14 PM
To: lml@lancaironline.net
Subject: Re: [LML] FW: [LML]
235/320/360 gear dump valve idea
Randy,
When I removed the plug in my pump a spring and a steel ball came out. Do
I remove these and then Install the 1/4" return line to this port?
Bryan
On Feb 7, 2008 10:34 AM, LHenney <LHenney@charter.net>
wrote:
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.
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%.
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...