 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
jonboede(at)hotmail.com
Guest
|
 Posted: Fri Nov 21, 2008 12:58 pm Post subject: brake differential valve |
 |
|
Where is the left/right brake distributor valve (QSF-2?) located (i.e. how does one get to it)?
Still working on that odd brake issue... after replacing the drums (but not the pucks C which seemed to be at full size) the airplane seems to have a left brake on taxi-out but seems to be lacking one after landing (although it has some C but not much).
I find this to be very odd. Pressure tests good at both brake line outlets at the wheels C about 150psi. I don't hear any hissing or see any air loss from holding the brake handle.
How does one tell if the distributor valve is acting whacky?
Thanks C
Jon
[quote][b]
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
 |
mark.bitterlich(at)navy.m
Guest
|
| Posted: Mon Nov 24, 2008 9:07 am Post subject: brake differential valve |
|
|
I do not know jack about YAK brakes. Mine are converted to Hyd toe
types, and I will never regret the change!
That said, one thing that is true of electricity, hydraulics, and to a
certain extent, even compressed air, is that pressure at rest remains
the same regardless of any resistance in the line. For example, you can
have 10,000 ohms of resistance in a wire, but with no current flow, your
volt meter will measure the same voltage coming into that wire as coming
out of it. Same thing goes with hydraulics.
Sooooo considering that fact, I think you might want to be cautious
about pressure checks and the resultant 150 PSI at both wheels as a
means of determining everything is OK. That is a static check. On the
other hand, when you apply the brakes, now you have fluid MOVING and
that is a whole different ball of wax. Now since there is flow, any
resistance in the line would come into play immediately.
To me, it sounds like you are getting enough pressure in the line to the
brake that when you actuate it, you get braking. After you land, ...
One assumes you used a lot of air. The air in the main tank went LOW
for awhile. Landing gear, flaps, etc., etc. You land, and the tank
refills, but the air available to the left brake is LOW due to a
restriction somewhere. So.. You let it sit for a few hours, and POOF,
the pressures equalize and it works again.
This is the only theory I can see that explains the facts. Not much
help in locating the problem... But my vote says it has to be a line
restriction.
Mark Bitterlich
--
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
dsavarese0812(at)bellsout
Guest
|
| Posted: Mon Nov 24, 2008 10:21 am Post subject: brake differential valve |
|
|
For about $65 one can purchase a brake differential valve overhaul kit from Doug Sapp. Very likely, the BDV is "sticking". There are little "pistons" and seals which cause the input air pressure to be diverted to the left and right depending on the position of the swing arm. It will take about an hour to R and R the BDV and overhaul it. My guess is the problem is in the BDV.
Dennis
[quote] ---
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
jonboede(at)hotmail.com
Guest
|
| Posted: Mon Nov 24, 2008 10:49 am Post subject: brake differential valve |
|
|
Turns out that it was a combination of three things:
1. Drums were slightly worn.
2. QS-2 valve had issues.
3. Front brake cable tension was slightly low.
Replaced the drums and QS-2 C backed out the adjustment on the front brake handle by about 1/3" and it seems to work great.
Jon
From: dsavarese0812(at)bellsouth.net
To: yak-list(at)matronics.com
Subject: Re: brake differential valve
Date: Mon C 24 Nov 2008 12:18:32 -0600
For about $65 one can purchase a brake differential valve overhaul kit from Doug Sapp. Very likely C the BDV is "sticking". There are little "pistons" and seals which cause the input air pressure to be diverted to the left and right depending on the position of the swing arm. It will take about an hour to R and R the BDV and overhaul it. My guess is the problem is in the BDV.
Dennis
[quote] ---
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
dougsappllc(at)gmail.com
Guest
|
| Posted: Mon Nov 24, 2008 11:12 am Post subject: brake differential valve |
|
|
Jon,
Be wary of the brake cable, cable does not just one day decide to stretch. It just might be getting ready to break. I have seen many of them seem a bit loose, then fail later after they were "snugged up". Keep an careful eye on it.
Doug
On Mon, Nov 24, 2008 at 10:47 AM, Jon Boede <jonboede(at)hotmail.com (jonboede(at)hotmail.com)> wrote:
[quote] Turns out that it was a combination of three things:
1. Drums were slightly worn.
2. QS-2 valve had issues.
3. Front brake cable tension was slightly low.
Replaced the drums and QS-2, backed out the adjustment on the front brake handle by about 1/3" and it seems to work great.
Jon
From: dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: brake differential valve
Date: Mon, 24 Nov 2008 12:18:32 -0600
For about $65 one can purchase a brake differential valve overhaul kit from Doug Sapp. Very likely, the BDV is "sticking". There are little "pistons" and seals which cause the input air pressure to be diverted to the left and right depending on the position of the swing arm. It will take about an hour to R and R the BDV and overhaul it. My guess is the problem is in the BDV.
Dennis
[quote] ---
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
nc69666(at)aol.com
Guest
|
| Posted: Mon Nov 24, 2008 9:01 pm Post subject: brake differential valve |
|
|
I had a brake cable go bad on my CJ, it happened very slowly, brakes kept getting weaker and weaker. Found the cable was fraying internally, replaced the cable and everything worked fine. Would be a good idea to replace the cable. Gary, CJ, N22YK
--
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
N642K
Joined: 23 Jul 2008
Posts: 84
|
| Posted: Mon Nov 24, 2008 9:15 pm Post subject: Re: brake differential valve |
|
|
How tough is it to replace the cable?
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
nc69666(at)aol.com
Guest
|
| Posted: Mon Nov 24, 2008 9:56 pm Post subject: brake differential valve |
|
|
It has been several years ago when I replaced it.. Trying to remember, but I fabricated the new cable myself from the center strand of a 7 X 19 cable I think it was the strand from a 3/32 nd cable and soldered the ends back on the cable as the original one had on it, getting the cable assembly out of the airplane was not too difficult as I remember. I would check with Doug or Dennis, as they may have a new one.. That would be the easiest way to go.. Gary
--
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
