Recently I needed to replace the small hand carryable compressor that I
keep at a house that I am renovating. I was looking for something cheap
and fairly light. I did OK on the cheap part but this little compressor
is mightly heavy. The E-bay listing did not mention the motor size, I
was expecting it to be 1/3 or 1/2 hp, hoping that it might be 3/4.
Instead it has a real 1 hp (13.2/6.6 A, 1725) moptor. My winning bid
was $4.25. I ended up paying the seller 9 bucks - I was so pleased to
have gotten a good size motor.

This is an old unit (the rubber tires have fallen off of the wheels) and
there is no relay to turn the motor on & off. When the compressor is
plugged in, the motor is running. When the compressor reaches the upper
pressure limit, the compressor quits pumping (motor never stops running,
compressor is always running). Once the low press limit is reached the
compressor resumes pumping. Looking at the tubing going up to the
valves, I presume that the compressor (pump) has pneumatic valves and
that the pneumatic valves open & remain open once the high press limit
has been reached. I have uploaded pics to the drop box:
http://www.metalworking.com/dropbox/...win-Briggs.txt

There is a problem with the compressor operation: there is either no
check valve or it is non-functional when the compressor is not pumping.
Once the high limit pressure is reached and the compressor pump
quits pumping the air in the tank bleeds out (rapidly, under 10 seconds
from 105 psi to 75 psi) thru the compressor air intake port. Once the
low pressure limit is reached the air stops leaking out of the air
intake. It takes about 8 sec for the two little tanks to fill from 75
psi to 105. Either a check valve is non-functional or one is needed. I
am leary of tearing open either the pressure relief valve or the top of
the compressor at the moment to see if there is a check valve since I
need to use the compressor right now and I am not certain I would be
able to diagnose a problem if I had either of the two valves apart.
Suggestions on what to look for when I finally tear into this thing?

As a short term work around, I am going to put a checkvalve on the input
to an auxillary 4 gal tank that I have so that I can connect the aux
tank to the compressor and maintain higher air pressure (instead of the
pressure ossilating from 75 to 105 to 75 every few seconds.