On 6/5/2010 7:22 PM, Milton Bland wrote:
John,
I am one of those subscribers who has a difficult time replying to the
thread, so I am replying directly to you.
I extended the cylinder enough that I could see through the filler cap
that it was past the piston cup. Then I filled it with DOT3. When I
pushed the cylinder back up, I got squirted pretty well. I was afraid
it still was not filled, so I did it all again, this time with a cloth
around the filler cap when as I slowly compressed the assembly. I am
fairly certain I got the full amount of fluid in.
I think I now understand how the oleo is supposed to work. If I am
correct, the initial push on the gear is dampened. Then the fluid
must run back through the hole in the bottom of the piston (or bolt)
before it can do any more work. That requires the gear to be
extended. So it is not much help taxiing, nor on the second bounce
on a "multi-bounce" landing. I will try to avoid those landings.
Milton:
"I got squirted pretty well" could mean one of 2 things. Either it was
excess fluid above the level of the fill hole or it was fluid being
forced past the seal instead of into the piston. (the former is normal;
the latter is bad)
The way it is supposed to work: as the gear compresses from full
extension, fluid is forced into the piston through the orifice,
compressing the air in the piston and absorbing the initial "drop". when
the cushions hit the top of the strut, or the spacer if installed,
further compression compresses the donuts. the hydraulic dampening still
occurs but its effect is minimal compared to the compression of the
donuts. As the plane bounces up and down fluid moves out of and back
into the piston. The compressed air in the piston pushes the fluid back
out when the load on the gear is reduced.
Two problem areas: (1)blockage of the oriface or "kukah" (instead of
air) in the piston itself or (2) a failed seal. The former will cause
the latter as the fluid is not compressible and must go somewhere. ( a
pretty good squirt...)
One diagnostic tool: Remove the bottom half of the strut and pour the
fluid into a jar. See if the amount that came out is enough to refill it
to just below the fill hole. If it is not, it's going somewhere it
doesn't belong.
--
John
Skyport East
www.skyportservices.net
