The Murphy Builders Site

Disconnected the air supply line to the spider and cracked the air
bottle open. Major air and no dirt/gunk--so the problem is not the air
supply.

Took the solenoids off the firewall, took them apart and cleaned them.
Just some oil and a few minor, very minor, particles. Made sure all the
parts functioned (springs good) and the very small holes in the solenoid
itself were clear.

Hooked the solenoids up to the coils (with the system disconnected from
the air). Just testing electrical operation of the coil/solenoid. Dump
solenoid works Ok; start solenoid seems to be very weak if it is
functioning at all. Switched things around to see if the problem was
the coil or the solenoid. Seems to be the solenoid itself based on
switching things.

Not sure why the solenoid would go bad after just 150 hrs total time on
the plane, so in effect perhaps far less than 150 total starts.

Will be calling Kimball's in the a.m. to order another solenoid / coil
mechanism. Would order two but I want to make sure that by replacing
one coil / solenoid that this cures the sluggish start problem.

Thank you for all your input Kevin.

Ted Waltman
303.378.4987
ted@i1ci.com

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
KJKimball@aol.com
Sent: Thursday, April 21, 2005 7:22 PM
To: rebel-builders@dcsol.com
Subject: Re: M-14 Kimball air start system question


Group,

I discussed the problems some of you are having with the air systems
with my
father, Jim. Basically, he agrees with the post I made a few days ago
concerning the use of the bypass valve, how to troubleshoot the system,
etc. He did
correct me on how our valves are mounted in the Pitts Model 12. They
are at
the same elevation relative to the bottle valve as I mentioned but are
not set
with the coils upright. The coil stem points forward toward the engine
and he
did this to avoid having valve action at high g loads.

Visit this page: moose support page and click on the air system photo.
Working from the left end, you can see the fitting that will attach via
hose to the
compressor. The left solenoid is the bypass valve and it has the
through run
vertical with the output pointing down. The start valve has the run
horizontal with the output to the start distributor on the left. As you
can see, both
solenoids have the stem and coil pointing horizontally toward the
engine.
The bottle is horizontal as well.

What have you guys found with testing the system?

Sincerely,

Kevin Kimball, VP Engineering
Jim Kimball Enterprises, Inc.
PO Box 849, 5354 Cemetery Rd.
Zellwood, FL 32798
407-889-3451 phone
407-889-7168 fax
http://www.jimkimballenterprises.com/
http://www.pittsmodel12.com/




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Fellas, although my experience with the Kimball system is limited to
buying one and storing it (for now), I can speak of experiences with
solenoids on other industrial equipment. For one, be VERY sure that
the coil in use matches the voltage at hand. A 24 volt coil will
likely work on 12 volts but may not pull the armature fully. If the
armature does not FULLY retract, the coil current will increase. It
may or may not be enough increase to blow a fuse (or pop a breaker)
but in time, the over current condition will create enough heat to
degrade the coil insulation and thus cause it to short, either fully
or partially. If the solenoid is fused properly, you'll note nuisance
fuse blowing. If a big enough fuse is in place, the coil will
eventually fail completley. If the proper coil is used, you can still
see this phenomenon if the body of the solenoid is bent ever so
slightly. The armature is a steel "plug" that operates inside a
stainless steel tube. The clearances aren't very large. If the tube
is slightly deformed, causing drag on the armature, it will not freely
operate, causing moments of high current and result in the same
failure. It doesn't take much to bend the tube just a bit. Ted, you
could have a bent solenoid or maybe the tube has enough gunk to cause
drag. The inside of the tube is 'wetted' by the fluid being
controlled, so it's possible to get snot into there. I'd personally
mount the solenoid with the coil pointing up, to minimize this
possibility. Don't take this as any criticism of Kevin's suggestion,
just different reasoning. If my solenoids are ever subjected to
enough negative G to open them, a bit of errant air flow will be quite
low on my list of problems...

Hope some of this is helpful.

Bill

On 4/21/05, Ted Waltman <tedwaltman@i1ci.com> wrote:

Disconnected the air supply line to the spider and cracked the air
bottle open. Major air and no dirt/gunk--so the problem is not the air
supply.

Took the solenoids off the firewall, took them apart and cleaned them.
Just some oil and a few minor, very minor, particles. Made sure all the
parts functioned (springs good) and the very small holes in the solenoid
itself were clear.

Hooked the solenoids up to the coils (with the system disconnected from
the air). Just testing electrical operation of the coil/solenoid. Dump
solenoid works Ok; start solenoid seems to be very weak if it is
functioning at all. Switched things around to see if the problem was
the coil or the solenoid. Seems to be the solenoid itself based on
switching things.

Not sure why the solenoid would go bad after just 150 hrs total time on
the plane, so in effect perhaps far less than 150 total starts.

Will be calling Kimball's in the a.m. to order another solenoid / coil
mechanism. Would order two but I want to make sure that by replacing
one coil / solenoid that this cures the sluggish start problem.

Thank you for all your input Kevin.

Ted Waltman
303.378.4987
ted@i1ci.com

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
KJKimball@aol.com
Sent: Thursday, April 21, 2005 7:22 PM
To: rebel-builders@dcsol.com
Subject: Re: M-14 Kimball air start system question

Group,

I discussed the problems some of you are having with the air systems
with my
father, Jim. Basically, he agrees with the post I made a few days ago
concerning the use of the bypass valve, how to troubleshoot the system,
etc. He did
correct me on how our valves are mounted in the Pitts Model 12. They
are at
the same elevation relative to the bottle valve as I mentioned but are
not set
with the coils upright. The coil stem points forward toward the engine
and he
did this to avoid having valve action at high g loads.

Visit this page: moose support page and click on the air system photo.
Working from the left end, you can see the fitting that will attach via
hose to the
compressor. The left solenoid is the bypass valve and it has the
through run
vertical with the output pointing down. The start valve has the run
horizontal with the output to the start distributor on the left. As you
can see, both
solenoids have the stem and coil pointing horizontally toward the
engine.
The bottle is horizontal as well.

What have you guys found with testing the system?

Sincerely,

Kevin Kimball, VP Engineering
Jim Kimball Enterprises, Inc.
PO Box 849, 5354 Cemetery Rd.
Zellwood, FL 32798
407-889-3451 phone
407-889-7168 fax
http://www.jimkimballenterprises.com/
http://www.pittsmodel12.com/

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