Another compressor problem

[Gregory OConnor]

PeteM sent a link to a booklet on air brakes.
http://www.gnb.ca/0276/vehicle/pdf/ab_manual-e.pdf
On page 12 of the 77 page pdf booklet is a good explanation of the
compressor on and off operation. The book is generic which would be
best with a 'as built' system like you have. Understanding of the
contents of the book is a requirement for a Federal commercial
drivers license CDL. This book may be a good pdf file to down load
and save for reading.

You hear the compressor strain when it is loading the tanks with
air. The governer directs flow of the 'compressor discharge line'
Governer is set to direct the discharge line to load the tanks when
tank pressure falls to 85#. therefor when the gov starts refilling
the tanks, it is pushing air against a pressure of 85 from the start
and you hear the strain.
When the tank is at max pressure the governer direction of air
pumped by the full time compressor switches to 'Unload', there is no
strain because unload is a circular path of air from and to the
compressor. (the term unload is not a depletion of tank pressure)

I do not believe that any component of the air brake system is
electrical.


<snip from page 12>
The compressor is in constant drive with the engine.
Whenever the engine is running, so is the compressor.
When pressure in the system is adequate, anywhere
from a low of 80 psi to a high of 135 psi it is not necessary
for the compressor to pump air. A governor (2) controls the
minimum and maximum air pressure in the system by
controlling when the compressor pumps air. This is
known as the "loading" or "unloading" stage. Most
compressors have two cylinders similar to an engine's
cylinders. When the system pressure reaches its
maximum, which is between 115 and 135 psi, the
governor places the compressor in the "unloading"
stage.


GregoryO'Connor
94ptRomolandCa


--- In WanderlodgeForum@yahoogroups.com, "bubblerboy64"
wrote:
>
> Ok, Where is the governor? You guys gotta remember I am pretty
much
> stupid on this stuff. The only thing on the compressor is what
> appears to be a small filter housing on right side of the thing
> looking into the engine bay from the front of the bus. Something
> obviously opens and or controls the compressor because when it is
> functioning I can hear it cycle on and off.
> John Heckman
> central Pa
> 1973 FC
>
>
>
>
> >
> > My guess is it's the governor, assuming there is a governor on
your
> coach.
> > Myself, others, have reported like problems and resolved the
> problem by
> > removing the old governor and installing a new (not rebuilt)
> governor.
> >
> > On Dec 31, 2007 6:36 AM, bubblerboy64 wrote:
> >
> > > Well, I went out and started the bus and wouldn't you know
it
> the
> > > compressor immediately kicked on and functioned as it should.
It
> > > cycled up to 125psi on the gauge and shut off and every thing
> seems
> > > fine. But we know that is not the case. Idea's thoughts
anything
> on
> > > this with this little bit more information.
> > > John Heckman
> > > central Pa
> > > 1973 FC
> > > >
> > > > I haven't had a chance to look into this today as yet. I
> appeciate
> > > > the help to this point. My question is what regulates the
> > > > compressor? The pulley is spinning all the time but I can
tell
> by
> > > the
> > > > sound that it cycles on an off as far as a load.The
compressor
> > > > mounting rattles rather noisily when it is changing the
tanks.
> > > Does
> > > > something close and open to fill the tanks? I have this idea
> again
> > > > perhaps I am wrong that this is electrical? Or as Gregory
said
> > > there
> > > > is a valve sticking. Now where are the valves? In the top of
the
> > > > compressor. Remember this thing is bits and pieces of parts
so
> > > that
> > > > makes it even more interesting. I had this occur before one
time
> > > and
> > > > my shore batteries were down. I got the batteries charged up
and
> > > the
> > > > compressor kicked in. Could be just lucky or a coincidence?
> Seems
> > > > like a leak would leak all the time rather then come and go.
I
> > > plan
> > > > on fooling around here today with it so I will be back and
> forth. I
> > > > guess the first thing I will do is just start the bus and try
> > > again.
> > > > I need to figure this out because at some point its going to
> stay
> > > > broke. Likely at the worst possible time. So I need to
> understand
> > > > the system a little better.
> > > > John Heckman
> > > > central Pa
> > > > 1973 FC
> > > >
> > > >
> > > >
> > > >
> > > > >
> > > > > John, if the belt is tight and the compressor is spinning
> check
> > > the
> > > > > key in the pully shaft???? you can also check to see if the
> > > > > compressor head gets hot???
> > > > >
> > > > > If it is a leak it must be big. you can not hear it
because it
> > > > wont
> > > > > build enough pressure to hiss and while the cat is running
> there
> > > is
> > > > > too much noise to hear a big leak hiss. I would hook the
aux
> air
> > > up
> > > > > to a remote shop compressor and look for a leak that way.
> build
> > > a
> > > > > male to mail fitting for a remote compressor line's female
end
> > > and
> > > > > try and build up the tanks in the bus that way?????? I
have
> had
> > > > > valves hang up that just needed a jolt of reverse air to
get
> thm
> > > > > free.
> > > > >
> > > > > It could also be that there is a blockage in the compressor
> > > output
> > > > > line to the first tank
> > > > >
> > > > > GregoryO'Connor
> > > > > 94ptRomolandCa
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > --- In WanderlodgeForum@yahoogroups.com > 40yahoogroups.com>,
> > > "bubblerboy64"
> > > > > wrote:
> > > > > >
> > > > > > Upon trying to take the son-in-law for a turn in the bus
I
> > > found
> > > > > that
> > > > > > the compressor would not bring the air up to release the
> > > brakes.
> > > > > > Checked and the belt is Ok and the compressors seems to
be
> > > > turning
> > > > > Ok.
> > > > > > Is there a solenoid or a switch which activates and
> deactivates
> > > > > the
> > > > > > compressor. I get about 30lbs on the air gauge but no
more.
> > > The
> > > > > only
> > > > > > other clue is that when the compressor is running
normally
> it
> > > > > makes
> > > > > > enough noise that I can hear it and it is not doing that.
> > > Don't
> > > > > know
> > > > > > beans about what I am dealing with but any help or
> suggestions
> > > as
> > > > > to
> > > > > > what to look at or for would certainly be appreciated.
> > > > > >
> > > > > > John Heckman
> > > > > > central Pa
> > > > > > 1973 FC converted to 3208 CAT
> > > > > >
> > > > >
> > > >
> > >
> > >
> > >
> >
> >
> >
> > --
> > Curt Sprenger
> > 1987 PT38 8V92 "MacAttack Racing"
> > Anaheim Hills, CA
> >
> >
> > [Non-text portions of this message have been removed]
> >
>