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RE: Europa-List: Tri-gear Jamar brakes

Subject: RE: Europa-List: Tri-gear Jamar brakes
From: Robert C Harrison <ptag.dev@tiscali.co.uk>
Date: Mon, 12 Oct 2009 19:51:17

Hi! Frans
I'm not familiar with the JAMAR term you use. I have trike foot brakes not
finger brakes. However I forced fluid up from the bottom using a lemonade
bottle linked to the nipple (You will be using a large vets SYRINGE)
However, have you realized that the bleed nipple at the brake end needs to
be on the bottom of the slave cylinder and the pipe connection to the master
cylinders need to be on the top?
Regards
Bob Harrison G-PTAG

-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Frans Veldman
Sent: 12 October 2009 12:02
Subject: Europa-List: Tri-gear Jamar brakes (breaks?)


In the archives I have seen that others have had problems with these
brakes as well, but few wrote what helped them to finally get rid of the
air, and/or to fix the unit.

I couldn't bleed my starboard brake by conventional means (from top to
bottom), but when I finally injected dot5 into the bleed nipple until
the level in the reservoir raised by 1/2, the brake was no longer
spongy. I couldn't get it to the end-stop anymore. Satisfied with how it
was, I decided not to mess anymore with it and I left it there. For
injecting the fluid I used an injection thing from the VET (don't know
the proper name in English) but instead of a needle, I attached a
plastic tube to it. This worked well. Needless to say I used quite a
large unit.

The port brake however, where I applied the same method, never got rid
of the air. Even worse, if I then try to bleed from top to bottom, I can
get one throw of the brake lever (with a squirt of fluid going out of
the bleed nipple) and after that, it feels like it is empty (no
resistance, and no significant fluid ejection).
Since I have been doing this at least 20 times (inject into the bleed
nipple until the reservoir level rises by half, followed by bleeding the
conventional way) I suspect something is wrong here.
I also winched the airplane halfway up the trailer, so it was pointing
its tail up, to easy any air out of the Jamar thing, but it didn't
change anything.

There was one anomaly: while it was pretty easy to inject the fluid on
the starboard side (the one that worked so well), it was in the
beginning almost impossible to get some fluid into the port side, it
gave a feeling like it was blocked. As the manual suggest that it should
be possible to do it this way, I increased force until it felt like
something gave way, and after that it was behaving and feeling like the
starboard side (except that it keeps feeling spongy, whatever I try, and
after one squirt it feels "empty").

Give the massive amounts of fluid I injected, and pressure applied, I'm
sure there are no leaks in the system (otherwise it would have left
obvious traces of the slippery stuff somewhere in the fuselage).

Actually, the brakes have worked for a while last year (although both
sides were somewhat spongy) when I installed the brakes and filled it up
with fluid to check its function, but never bothered to get it
completely free of air, because I figured that I would have to
disconnect something again in a later stage. Now I'm preparing for
"first flight" and tries to get everything in perfect condition, I seem
to be stuck with this...

Any ideas? Should I try harder, or might something be wrong with the
Jamar unit? Do the symptoms indicate a fault?

Frans



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