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From: RWolf99@aol.com
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Date: Fri, 5 Feb 1999 02:34:19 EST
To: lancair.list@olsusa.com
Subject: Hydraulic Cylinders
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In a message dated 2/4/99 9:56:10 PM, you wrote:

<<is there some sort of lube in the AROTEK cylinders so wear during dry
cycling does not excessively wear the 
seals.>>

I had to replace the cylinder body for my 360 nose gear door cylinder.  I was
trying to drill out the bolt hole to #10 and screwed it up, making a big oval
hole.  Anyways, for $35 I got a replacement body from Arotek (Vern at Lancair
gave me the number) and transferred the guts from one body to the other.

Here's what I found.   The cylinder insides are easily removed by taking off
the snap ring.  The cylinder rod has O-ring seals (DUH!) which are lubricated
by a grease.  So I don't think you'll be scratching the insides if they are
empty of fluid.  Keep the openings plugged or capped whenever you can,
although you might have to remove the cap to let air flow in and out as you
manually cycle the thing.  But when you're grinding in the vicinity, cap it
off.  I bought a dozen AN fitting caps for this purpose, but a baggie and a
rubber band would work as well.

By the way, I had earlier encountered some difficulty installing the NPT
threads of the fittings into the cylinder.  Felt like it was cross-threaded
even though it wasn't.  When I took the cylinder apart I found metal shavings
inside (one or two slivers) up against the O-ring.  These were the threads
that I sheared off screwing on the fittings.  I pulled them out with tweezers
and smeared a little of the excess grease over the O-ring when I put the guts
into the new (dry) cylinder.  So I plan to pop off the snap ring and clean out
each cylinder before I put the fluid in for the first time.  It should take
about five minutes per cylinder (once it's on the bench).  I recommend anyone
who has felt a fitting go in "sorta crosswise" take the cylinder apart and
check if you haven't added fluid yet.  If you have your system full, I'd leave
it alone until it starts to leak (which may never happen).  Why do extra work
when the worst possible failure mode is only a small leak?

- Rob Wolf
rwolf99@aol.com