Posted for "Randy" <randystuart@hotmail.com>:
Since
Marv (LML) has decided to not let the group read ALL the emails
involved in this discussion I will let the LML users make up their own
mind on
what they think is best for their Lancair.
Anyone that knows how this system works and the problem with some of the
Oildyne
pumps will know how the mods work and if they are suited for their
Lancair.
Randy Stuart
LNC-2
[Just so we are
clear... every post but one in this discussion has made
it to the LML. I do not allow name calling here... keep it civil and
it will be posted. It doesn't get any simpler. <marv>]
----- Original Message -----
From: Wolfgang
To: lml@lancaironline.net
Sent: Friday, October 23,
2009 6:49 AM
Subject: [LML] Fw: Not a good idea
Randy, I'm confused. I'll keep this on a technical
focus.
Your gear operation modifications include replacing the HI pressure switch,
adding a second pressure switch to the LO
circuit and doing some re-wiring of
the gear circuit.
The result is that when flying along with the gear UP and hydraulic
pressure
happens to build in the LO side, your modification will drive the pump to
start LOWERING the gear while the gear switch is still in
the UP position.
This is alarming! This will of course reduce the pressure in the HI side
causing the HI pressure switch to trip which now
reverses the pump and drives
the gear back up, finally reducing the pressure in the LO side. With the
immediate reversing of the motor, surge
currents will be excessive and could
possibly trip the pump circuit breaker.
What manner of experience and/or engineering
allows you to consider this
operation a good idea ?
Additionally, when on the ground, gear down, and the HI side happens to
build too much pressure (which prevents raising the gear), your modification
is not able to offer any help.
- - - - - - - - - - - -
- - - -
The fix I developed does not require any re-plumbing, just adding a small
module at the existing pressure switches
without requiring any tools to
install the push-on connectors. When necesssary, it runs the pump in the
direction selected by the current
position of the gear switch which relieves
the pressure in the opposite side. Also, the module is fully symetric and
offers help with both HI
side and LO side undesired pressure build up.
Wolfgang
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