Wolfgang,
<<“I believe in redundancy and it looks like you
don't….”>>
I am a big proponent of redundancy. That is redundancy defined as a true back-up
to an otherwise trouble-free system.
First, I have redundant switches to power the pump
solenoids. This allows me to raise and
lower the gear in case of the failure of either of the pressure switches. It doesn’t happen very often, but it does
happen - twice in 17 years of flying my 360.
I also have redundant gear down indications. Two completely separate systems, separate switches,
separate wires and separate indicators.
The second set of switches is mounted directly on the over-center links.
I even carry two iPads and a iPhone - just in case
<<“The pressure pulse you're talking about will
subside (glad you agree) and as it does, because the cylinder is only partially
extended, the cylinder will continues to extend, the low switch will close
again, and enable the pump to continue . .”>>
The part you seem to be missing here is that the momentary
pulse is not directly turning off the pump.
Thus when the pulse subsides, the pump doesn’t just spring back to
life. The pulse pushes the spool in the
wrong direction -against the pump flow.
This locks the poppet that the pump just opened up a fraction of a
second earlier. When this happens, the
high side begins to pressurize along with the low side. As soon as both sides reach the low side
pressure setting, the pump is turned off.
This is why you see both high and low circuits pressurized to the same
value in Lorn’s photo.
To prevent this, the low side pressure settings should be
raised. 800 psi has proven
sufficient. The high volume gear pump
will reduce the size of the pulse since the higher volume pump is able to
absorb incoming fluid at a higher rate.
I highly recommend pressure gauges for both high and low
circuit be installed in a location visible to the pilot. The state of the system can always be
verified. One can immediately diagnose any
in-flight problem. Leaks can be caught
early. And adjusting pressure settings
is no longer guess work.
Chris Zavatson
N91CZ
360std
www.N91CZ.net