Hey Guys,
I'm selling My C22 sailboat and trailer for
$1000.00. If Your interested give Me a call.
Need the cash for the GMC.
Later,
Rob Teed 74 Painted Desert
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of
> EMERYSTORA
> Sent: Saturday, January 30, 1999 9:52 PM
> To: gmcmotorhome
> Subject: Re: GMC: Thomas Compressor/Vacuum pump
>
>
>
>
>
> compress. A compressor must have air to compress. Vacuums dont
> compress. Where is the compressor going to get the air to compress--
> surely not from a vacuum? Now it might find a little air but surely its
> ability to compress will be severely degraded.>>
>
> Arch - I hate to tell you but you have it wrong. A solenoid
> valve would open
> so that the inlet of the pump would draw outside air (atmospheric
> pressure)
> when it is in compression mode. It would not try to suck
> pressure out of the
> vacuum line.
>
> have to fire up with 120 PSI built up in the air tank this is only 30 PSI
> from its limit. Where is it going to put the air that it is
> taking out of the
> booster---------in the air tank--------mine has a 150 PSI pop-off------the
> limit of the compressor-----------I dont think I am going to get much
> vacuum under those conditions. Not to mention how little faith I have in
> pop-off valves.>>
>
> Arch - Another solenoid valve would open so that the inlet of the
> pump would
> exhaust to the outside air (atmospheric pressure) when it is in
> vacuum mode.
> It would not pump against the pressure in the air tank.
>
> at atmospheric pressure not at 120 PSI !>>
>
> Arch -- this is totally correct and that is how the system would
> work if the
> plumbing is done correctly.
>
> on this one.>>
>
> Yes, in my past life I was an engineer, also a corporate
> assistant treasurer,
> an investment banker, and owner of my own company prior to
> retiring at 55 last
> February -- this makes me somewhat of a typical GMC owner - I
> now have time
> to work on the GMC.
>
> Arch -- I think that you should reread the original threads of
> this pump. I
> deleted them so I cannot refer to them until the archives come
> out, but I am
> certain that it indicated valves would close off the air tank
> when in a vacuum
> mode and open that side of the pump to the atmosphere.
> Conversely, when in a
> compression mode the valves would open the intake side to the
> atmosphere and
> close the connection to the vacuum line.
>
> My personal feelings are that anyone would be much better off to
> retrofit the
> vacuum brakes with the vacuum pump used on 4 cyl. air conditioned Chevy,
> Cadillac, etc. vehicles in the 80's. These can be picked up at a
> junkyard for
> $10 to $25. and be easily installed without a lot of solenoids
> and switches
> that only give more things to go wrong.
>
> If your Dana compressor is not working right you can get an
> upgrade kit from
> Cinnabar for about $50.00. I believe that there is a write up on
> Patrick's
> site about this.
>
> I would never recommend anyone to go to an air pump that would
> also serve as a
> vacuum pump. I'm sure that I could make it work but it would
> mean running air
> lines or vacuum lines from the rear wheel area to the front
> vacuum brake area.
> It would also need wires running back and forth and several
> electric solenoid
> valves. By keeping the two functions separate I anticipate that I'll have
> much less problems with either system. Engineers call this the
> KISS method.
> "Keep it Simple Stupid".
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
I'm selling My C22 sailboat and trailer for
$1000.00. If Your interested give Me a call.
Need the cash for the GMC.
Later,
Rob Teed 74 Painted Desert
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of> EMERYSTORA
> Sent: Saturday, January 30, 1999 9:52 PM
> To: gmcmotorhome
> Subject: Re: GMC: Thomas Compressor/Vacuum pump
>
>
>
>
>
> compress. A compressor must have air to compress. Vacuums dont
> compress. Where is the compressor going to get the air to compress--
> surely not from a vacuum? Now it might find a little air but surely its
> ability to compress will be severely degraded.>>
>
> Arch - I hate to tell you but you have it wrong. A solenoid
> valve would open
> so that the inlet of the pump would draw outside air (atmospheric
> pressure)
> when it is in compression mode. It would not try to suck
> pressure out of the
> vacuum line.
>
> have to fire up with 120 PSI built up in the air tank this is only 30 PSI
> from its limit. Where is it going to put the air that it is
> taking out of the
> booster---------in the air tank--------mine has a 150 PSI pop-off------the
> limit of the compressor-----------I dont think I am going to get much
> vacuum under those conditions. Not to mention how little faith I have in
> pop-off valves.>>
>
> Arch - Another solenoid valve would open so that the inlet of the
> pump would
> exhaust to the outside air (atmospheric pressure) when it is in
> vacuum mode.
> It would not pump against the pressure in the air tank.
>
> at atmospheric pressure not at 120 PSI !>>
>
> Arch -- this is totally correct and that is how the system would
> work if the
> plumbing is done correctly.
>
> on this one.>>
>
> Yes, in my past life I was an engineer, also a corporate
> assistant treasurer,
> an investment banker, and owner of my own company prior to
> retiring at 55 last
> February -- this makes me somewhat of a typical GMC owner - I
> now have time
> to work on the GMC.
>
> Arch -- I think that you should reread the original threads of
> this pump. I
> deleted them so I cannot refer to them until the archives come
> out, but I am
> certain that it indicated valves would close off the air tank
> when in a vacuum
> mode and open that side of the pump to the atmosphere.
> Conversely, when in a
> compression mode the valves would open the intake side to the
> atmosphere and
> close the connection to the vacuum line.
>
> My personal feelings are that anyone would be much better off to
> retrofit the
> vacuum brakes with the vacuum pump used on 4 cyl. air conditioned Chevy,
> Cadillac, etc. vehicles in the 80's. These can be picked up at a
> junkyard for
> $10 to $25. and be easily installed without a lot of solenoids
> and switches
> that only give more things to go wrong.
>
> If your Dana compressor is not working right you can get an
> upgrade kit from
> Cinnabar for about $50.00. I believe that there is a write up on
> Patrick's
> site about this.
>
> I would never recommend anyone to go to an air pump that would
> also serve as a
> vacuum pump. I'm sure that I could make it work but it would
> mean running air
> lines or vacuum lines from the rear wheel area to the front
> vacuum brake area.
> It would also need wires running back and forth and several
> electric solenoid
> valves. By keeping the two functions separate I anticipate that I'll have
> much less problems with either system. Engineers call this the
> KISS method.
> "Keep it Simple Stupid".
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
