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Chris,
I will check the part # on the pump tomorrow. Today
when I was at the hangar I looked at the low side of
the system. It indicated 600 psi. The high side was 0.
I opened the dump valve and both sides equalized at
around 300 or so. I closed the dump valve and turned
on the master switch. the pump came on and pumped the
down side back up to 600 or so and the up side went
back to 0.
Should the high and low sides equalize at something
other than 0?
Randy.
--- Christopher Zavatson
<Christopher.Zavatson@baesystems.com> wrote:
Randy,
<<I am absoluteley baffled over how both the high
and low sides build
pressure during flight.
Thoughts?>>
Your case is somewhat perplexing. The retention of
pressure would
indicate a reversed spool valve, but only seeing 200
psi during
retraction does not. If the system only retains 200
psi (normal while
pumping), how does it retain 600 psi while static? What bothers me is
that the fundamental purpose for the back pressure
circuit is to relieve
pressure on the low side to avoid tripping the
pressure switch
As an aside, I always view pumps coming straight
from Oildyne as
suspect until operational tests confirm correct
assembly. Back in the
'98 time frame, I had my pump in for servicing - I
let it run dry while
working on some cylinders. Their shop manager
called me to find out why
my spool valve was in backwards. After several
minutes describing the
hydraulic system to him, he determined that my
'backward' spool valve
was actually correct. The build instructions were
wrong. Low and
behold, one pump after another in the field started
exhibiting the
symptoms of a reversed spool valve. I don't know if
the paperwork ever
got fixed. Even the pump I had borrowed while mine
was out had a
reversed spool valve. I had to crank up the high
pressure side to get
the gear up all the way. Are you able you retrieve
a part number off
your pump?
Chris
Chris Zavatson
N91CZ
360std.
www.N91CZ.com
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