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