On Mar 11, 1:47*pm, Frank wrote:
My Cobra trailer hydraulic jack is starting to fail, to the point
where I now have to put a 2x4 board under the jack assembly to get my
wheel off the ground.

John Dezutti (7K) gave me some hydraulic fluid, but there doesn't seem
to be a good way to add fluid. *I tried, and got everything *but* the
jack filled with fluid, and got no discernable improvement in
performance.

I'm also told that the hydraulic piston is exactly the same as some
found in automotive hydraulic floor jacks, and that I might be better
off just replacing the unit rather than trying to repair it.

Can anyone out there help out a fellow pilot with a limp er, jack?

Frank (TA)

It is just a hydralic pump/ram assembly from a floor jack, I believe
Spindelberger actually take them out of floor jacks, but I could be
wrong. I sure wish they'd find something better. I believe they have
tried.

I would remove the jack and flush it and refill, Look for previous
r.a.s posts by bumper and others.

And if you need help look at this http://www.hyjacks.com/H7.HTM (Gawd
dang this Internet thing is amazing...)

If that does not work then replace it. It may be easier to pay the $85
or so plus shipping for a real Cobra replacement. Make sure you order
the right model for your trailer. Williams Soaring and probably other
places have them in stock. Some people have posted before about
finding a suitable unit in a floor jack. I'd be interested if somebody
found a high-quality floor jack part that would fit with some work
(and I'd expect that to cost lots more than buy another part from
Cobra). Other people have previously talked about customizing/
repairing up the standard Cobra units. I'm not sure if anybody is
offering to do that as as service.

Ah this reminds me I want to flush my Jack fluid....

I do not trust the hydraulic jacks and have a wood block that slides
into the bottom metal U channel and a block with a triangular shaped
top that slides under the jack scissors, It can't fall out because of
a lips that locate it in place. With a heavy motorglider I never want
to face the lift scissors bottomed out and unable to lift the
fueslage. Even though I have the safety blocks I also am careful never
to put the gear down until the wings are on. That can be a ~$5 lesson
(for a new canopy).


Darryl

Darryl