REFLECTOR: Retract Pressures

[Al Gietzen]

I told him that I had to raise the setting of my HP switch to over 1400 psi
with a gauge attached during construction.  When I started my flight tests,
this setting proved to be too low - the pump would cycle on and off every
couple of seconds. I turned the screw some more, until the pump would run
without pulsing, but the pressure gauge was not connected at the time so I
do not know what the pressure setting wound up being - but above 1400 for
sure.

 

Any body got a measurement for what their high pressure switch is set at for
actual operations?

 

Ronnie;

 

My switch is set for a bit less than 1050; but the pressure spikes past that
at the end of the stroke.  My measurements showed that it only took about
450 psi to raise the gear, but there was nearly another 400 psi pressure
drop in the ¼” lines.  The volumetric output of the pump far exceeds the
capacity of the lines.

 

Is that 1400 psi pressure needed to maintain gear movement, or is that an
initial pressure to release the lock on the OC linkage? Or is that the
pressure at the end of the stroke.  I noted early on that it took an
unnecessarily high pressure to release the lock because of the lever arm of
the release spring.  I moved the spring about 4-5” closer to the pivot, and
alleviated that issue.

 

As I recall, the internal by-pass in the pump releases at about 1400.  

 

Al

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