I attempted to post this earlier but it has not appeared. Hope it
doesn't pop up twice.

I recently bought a military surplus 2 stage Curtis-Toledo compressor
driven by about a 12HP B&S engine.

I cannot get the compressor to turn over by turning the flywheel. The
oil in the compressor and the engine is brand new. I don't know why
the military auctioned off the compressor.

I'm wondering if it got water in it or something. How can I get some
light weight oil into the cylinder? If it's toast is a rebuild a
major big $$$ undertaking?

Thanks,

Vernon

Separate the motor and the compressor. Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Vernon" wrote in message
...
I attempted to post this earlier but it has not appeared. Hope
it
doesn't pop up twice.

I recently bought a military surplus 2 stage Curtis-Toledo
compressor
driven by about a 12HP B&S engine.

I cannot get the compressor to turn over by turning the
flywheel. The
oil in the compressor and the engine is brand new. I don't know
why
the military auctioned off the compressor.

I'm wondering if it got water in it or something. How can I get
some
light weight oil into the cylinder? If it's toast is a rebuild
a
major big $$$ undertaking?

Thanks,

Vernon

On 2008-10-05, DanG wrote:
Separate the motor and the compressor. Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.


I unstuck a frozen compressor once by using a hydraulic jack to turn
the flywheel. I tried to be careful and inthe end, did not damage
anything.
--
Due to extreme spam originating from Google Groups, and their inattention
to spammers, I and many others block all articles originating
from Google Groups. If you want your postings to be seen by
more readers you will need to find a different means of
posting on Usenet.
http://improve-usenet.org/

DanG wrote:
Separate the motor and the compressor. Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.


I've known folks to swear by Marvel Mystery Oil. Just pour generously into the cylinder
heads and let stand. Then use a cheater. You may wait days or weeks but it will
eventually penetrate it.

On Oct 5, 7:34*am, "DanG" wrote:
Separate the motor and the compressor. *Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. *Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.

--
______________________________
Keep the whole world singing . . . .
DanG *(remove the sevens)


"Vernon" wrote in message

...



I attempted to post this earlier but it has not appeared. *Hope
it
doesn't pop up twice.

I recently bought a military surplus 2 stage Curtis-Toledo
compressor
driven by about a 12HP B&S engine.

I cannot get the compressor to turn over by turning the
flywheel. *The
oil in the compressor and the engine is brand new. *I don't know
why
the military auctioned off the compressor.

I'm wondering if it got water in it or something. *How can I get
some
light weight oil into the cylinder? *If it's toast is a rebuild
a
major big $$$ undertaking?

Thanks,

Vernon- Hide quoted text -

- Show quoted text -

Dan and everybody,

Indeed I have already separated the engine from the compressor. I
removed the protective cage from the belt drive and removed the
belts. Prior to doing that I thought that the Briggs & Stratton
engine was icky although it did turn. After removing the two V belts
it became clear to me that the motor is entirely free. The belts were
simply slipping on the large compressor fly wheel.

Is there a way to get oil in there without removing the head? My
problem is that I don't know anything about the innards of
compressors. This appears to be a single cylinder 2 stage compressor
good for 175psi at 15 cfm (if my memory serves which often doesn't).

If I get the thing to turn freely does this imply that it's "good to
go"? Or is machine work called for?

Thanks!

V

On Oct 5, 11:30*am, Al Patrick wrote:
DanG wrote:
Separate the motor and the compressor. *Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. *Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.

I've known folks to swear by Marvel Mystery Oil. *Just pour generously into the cylinder
heads and let stand. *Then use a cheater. *You may wait days or weeks but it will
eventually penetrate it.

Al,

I'm one of those who swears by MMO. I buy it by the gallon. When I
buy a reciprocating engine that's been out of commission I generally
dump some down the spark plug hole. However, I don't know how you
reach the top of a piston in a compressor.

V

Vernon wrote:


Al,

I'm one of those who swears by MMO. I buy it by the gallon. When I
buy a reciprocating engine that's been out of commission I generally
dump some down the spark plug hole. However, I don't know how you
reach the top of a piston in a compressor.

V

If you don't see any other way take the piping loose that links the compressor to the
tank. You should be able to get some in there, perhaps not enough, but it would be a
start.

I knew a young man 25 years ago who pulled the injectors for an old single barrel earth
mover, poured in a bunch of MMO and went back a week or so later with a good cheater. It
turned right over. Good stuff.

On Oct 5, 7:34*am, "DanG" wrote:
Separate the motor and the compressor. *Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. *Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.

--
______________________________
Keep the whole world singing . . . .
DanG *(remove the sevens)


"Vernon" wrote in message

...



I attempted to post this earlier but it has not appeared. *Hope
it
doesn't pop up twice.

I recently bought a military surplus 2 stage Curtis-Toledo
compressor
driven by about a 12HP B&S engine.

I cannot get the compressor to turn over by turning the
flywheel. *The
oil in the compressor and the engine is brand new. *I don't know
why
the military auctioned off the compressor.

I'm wondering if it got water in it or something. *How can I get
some
light weight oil into the cylinder? *If it's toast is a rebuild
a
major big $$$ undertaking?

Thanks,

Vernon- Hide quoted text -

- Show quoted text -

Dan, I imagine the active ingredient in Coca Cola is phosphoric
acid? If you use Coke do you use sugar free? Seems like the 9 tsp of
shooga down inside there would be kinda gooey.

V

Removing the heads should be quite straight forward. There should
not be any loose parts inside, just a reed plate. Make some kind
of mark so you can put it back on the same way it came off. There
should be about 6 bolts holding it on, bump the head with safe
hammer or wood block to pull the reed plate. Unlike internal
combustion engines, there is no timing or sequence to the
compressor head.

No one can tell you what is wrong with the compressor yet. Either
the rings are rusted in the cylinders or the rod caps are galled
to the crank. If it is light rust, you may not need to do
anything else.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Vernon" wrote in message
...
On Oct 5, 7:34 am, "DanG" wrote:
Separate the motor and the compressor. Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar
release
agent. Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)


"Vernon" wrote in message

...



I attempted to post this earlier but it has not appeared. Hope
it
doesn't pop up twice.

I recently bought a military surplus 2 stage Curtis-Toledo
compressor
driven by about a 12HP B&S engine.

I cannot get the compressor to turn over by turning the
flywheel. The
oil in the compressor and the engine is brand new. I don't
know
why
the military auctioned off the compressor.

I'm wondering if it got water in it or something. How can I
get
some
light weight oil into the cylinder? If it's toast is a rebuild
a
major big $$$ undertaking?

Thanks,

Vernon- Hide quoted text -

- Show quoted text -

Dan and everybody,

Indeed I have already separated the engine from the compressor. I
removed the protective cage from the belt drive and removed the
belts. Prior to doing that I thought that the Briggs & Stratton
engine was icky although it did turn. After removing the two V
belts
it became clear to me that the motor is entirely free. The belts
were
simply slipping on the large compressor fly wheel.

Is there a way to get oil in there without removing the head? My
problem is that I don't know anything about the innards of
compressors. This appears to be a single cylinder 2 stage
compressor
good for 175psi at 15 cfm (if my memory serves which often
doesn't).

If I get the thing to turn freely does this imply that it's "good
to
go"? Or is machine work called for?

Thanks!

V

On 2008-10-05, Vernon wrote:
I attempted to post this earlier but it has not appeared. Hope it
doesn't pop up twice.

It did show up. I see that you're posting from googlegroups,
and you should be warned that it can sometimes take several hours
between posting an article there and actually having it show up there.
However, the articles get to the outside world (where news servers work
properly) fairly quickly.

By now, you should be able to see quite a few answers to your
first try. (At least *I* saw several answers.)

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Oct 5, 10:35*pm, "DoN. Nichols" wrote:
On 2008-10-05, Vernon wrote:

I attempted to post this earlier but it has not appeared. *Hope it
doesn't pop up twice.

* * * * It did show up. *I see that you're posting from googlegroups,
and you should be warned that it can sometimes take several hours
between posting an article there and actually having it show up there.
However, the articles get to the outside world (where news servers work
properly) fairly quickly.

* * * * By now, you should be able to see quite a few answers to your
first try. *(At least *I* saw several answers.)

* * * * Good Luck,
* * * * * * * * DoN.

--
*Email: * * | Voice (all times): (703) 938-4564
* * * * (too) near Washington D.C. |http://www.d-and-d.com/dnichols/DoN.html
* * * * * *--- Black Holes are where God is dividing by zero ---

Don,

Thank you for the gentle, tactful admonition about google groups.
This led me to noodle around a little about the issue.

The result is that I have only now learned that google groupers are as
reviled and belittled as PETA activists, tree huggers, and AOL users!

Holy smokes, batman! I didn't know!

What do y'all use? Specialty news readers?

Sheepishly,

Vernon

Vernon wrote:
(...)

What do y'all use? Specialty news readers?

I use Mozilla but I understand there are programs out there
with very sophisticated message and thread filtering.

Need a newsgroup server?
http://www.aioe.org

It's Free!

--Winston

On Sun, 5 Oct 2008 21:40:45 -0700 (PDT), the infamous Vernon
scrawled the following:

On Oct 5, 10:35*pm, "DoN. Nichols" wrote:
On 2008-10-05, Vernon wrote:

I attempted to post this earlier but it has not appeared. *Hope it
doesn't pop up twice.

* * * * It did show up. *I see that you're posting from googlegroups,
and you should be warned that it can sometimes take several hours
between posting an article there and actually having it show up there.
However, the articles get to the outside world (where news servers work
properly) fairly quickly.

* * * * By now, you should be able to see quite a few answers to your
first try. *(At least *I* saw several answers.)

* * * * Good Luck,
* * * * * * * * DoN.

--
*Email: * * | Voice (all times): (703) 938-4564
* * * * (too) near Washington D.C. |http://www.d-and-d.com/dnichols/DoN.html
* * * * * *--- Black Holes are where God is dividing by zero ---

Don,

Thank you for the gentle, tactful admonition about google groups.
This led me to noodle around a little about the issue.

The result is that I have only now learned that google groupers are as
reviled and belittled as PETA activists, tree huggers, and AOL users!

Holy smokes, batman! I didn't know!

What do y'all use? Specialty news readers?

Ayup. Wes posts a statistical list of the readers used on a weekly
basis. It shows the top writers (and arseholes) of the group and a few
other tidbits. Those not using MS Outlook Express use Forte Agent (as
do I) and half a dozen others. I started with Free Agent and upgraded
to the paid version. That $29 lasted ten years, when I finally
upgraded again to v4.2. Alas, I still await a text search function
which will allow me to kill entire threads if they're started by
Cliffy or other trolls. That's the only thing I find wanting with
Agent. It's rock solid programming and I can't gush enough for it.

Google this group for "which newsreader" to get the entire history of
this question, Vernon. It is frequently asked.

--
"Given the low level of competence among politicians,
every American should become a Libertarian."
-- Charley Reese, Alameda Times-Star (California), June 17, 2003

On Sun, 5 Oct 2008 15:02:12 -0700 (PDT), Vernon
wrote:


Indeed I have already separated the engine from the compressor. I
removed the protective cage from the belt drive and removed the
belts. Prior to doing that I thought that the Briggs & Stratton
engine was icky although it did turn. After removing the two V belts
it became clear to me that the motor is entirely free. The belts were
simply slipping on the large compressor fly wheel.

Is there a way to get oil in there without removing the head? My
problem is that I don't know anything about the innards of
compressors. This appears to be a single cylinder 2 stage compressor
good for 175psi at 15 cfm (if my memory serves which often doesn't).

It can't be a single cylinder and a two stage at the same time...

Two stage normally implies a multiple of two (four, six, eight)
cylinders - and the second stage will be physically smaller. Of
course, they could do something really odd like having three feed
two...


If I get the thing to turn freely does this imply that it's "good to
go"? Or is machine work called for?

Depends on the condition of the other internal components - it might
turn freely and be fine after freeing up a stuck ring and minor
repairs like that missing air cleaner. It might have to get torn down
for inspection and possible internal parts replaced. You won't know
for sure until you get it spinning and see if it'll pump- they usually
make strange noises as a warning if it has bad problems inside.

You have a piston going up and down in a honed smooth and round bore
with piston rings to make a positive seal, just like a gasoline
engine, with a crankshaft and connecting rods with babbitt or ball
bearings just like an engine.

And oil seals at the ends of the crankshaft to keep the oil in, and
either oil slingers on the connecting rods or a pressurized oil system
for lubrication just like an engine.

The only big difference is instead of mushroom style valves and a
camshaft in an engine, you have reed valves or other simple check
style valves for controlling air in and air out in the heads. And no
sparkplug or other 'direct access' to the cylinder.

And for gasoline engine driven compressors you have an "Unloader"
system that holds the valves open to stop the pumping, and releases
the throttle to allow the engine to remain running and drop to idle
when the call for air stops.

(This is also useful in big shops with constant air usage but not
requiring the full output, like in sandblasting or multiple machine
tools. It's bad to start an electric motor more than 4 to 5 times an
hour, they burn up. And you have to pay Demand Charge adders on the
electric power bill from all those start surges - better to start the
motor once per shift and let it run unloaded when not needed.)

Compressors with pressurized lubrication also use that oil to run
the unloader valves, so the pump won't stall out the prime mover
(electric or gasoline) by starting to pump until after the compressor
gets up to full speed - and is not out of lube oil. (Safety system.)
If you see an oil pump and small pressure gauge on the end of the
crank opposite the pulley, possibly a small spin-on filter, and an
~1/8" oil line heading up to the heads, you have this.

Oh, and copper head gaskets can be annealed with a torch to dull red
hot (double check that temperature before trying, it's from memory)
and reused at least once in a pinch. But parts should be cheap and
easy, they do not make many radical design changes - the 2008 units
look a lot like the 1950 units. If it ain't broke...

That's it in a nutshell, and in English. When you're done give it
back, I've got a hankerin' for walnuts... ;-)

-- Bruce --

On Oct 6, 12:54*pm, Bruce L. Bergman
wrote:
On Sun, 5 Oct 2008 15:02:12 -0700 (PDT), Vernon
wrote:

Indeed I have already separated the engine from the compressor. *I
removed the protective cage from the belt drive and removed the
belts. *Prior to doing that I thought that the Briggs & Stratton
engine was icky although it did turn. *After removing the two V belts
it became clear to me that the motor is entirely free. *The belts were
simply slipping on the large compressor fly wheel.

Is there a way to get oil in there without removing the head? *My
problem is that I don't know anything about the innards of
compressors. *This appears to be a single cylinder 2 stage compressor
good for 175psi at 15 cfm (if my memory serves which often doesn't).

* It can't be a single cylinder and a two stage at the same time...

* Two stage normally implies a multiple of two (four, six, eight)
cylinders - and the second stage will be physically smaller. *Of
course, they could do something really odd like having three feed
two...

If I get the thing to turn freely does this imply that it's "good to
go"? *Or is machine work called for?

* Depends on the condition of the other internal components - it might
turn freely and be fine after freeing up a stuck ring and minor
repairs like that missing air cleaner. *It might have to get torn down
for inspection and possible internal parts replaced. *You won't know
for sure until you get it spinning and see if it'll pump- they usually
make strange noises as a warning if it has bad problems inside.

* You have a piston going up and down in a honed smooth and round bore
with piston rings to make a positive seal, just like a gasoline
engine, with a crankshaft and connecting rods with babbitt or ball
bearings just like an engine.

* And oil seals at the ends of the crankshaft to keep the oil in, and
either oil slingers on the connecting rods or a pressurized oil system
for lubrication just like an engine.

* The only big difference is instead of mushroom style valves and a
camshaft in an engine, you have reed valves or other simple check
style valves for controlling air in and air out in the heads. *And no
sparkplug or other 'direct access' to the cylinder.

* And for gasoline engine driven compressors you have an "Unloader"
system that holds the valves open to stop the pumping, and releases
the throttle to allow the engine to remain running and drop to idle
when the call for air stops.

* (This is also useful in big shops with constant air usage but not
requiring the full output, like in sandblasting or multiple machine
tools. *It's bad to start an electric motor more than 4 to 5 times an
hour, they burn up. *And you have to pay Demand Charge adders on the
electric power bill from all those start surges - better to start the
motor once per shift and let it run unloaded when not needed.)

* Compressors with pressurized lubrication also use that oil to run
the unloader valves, so the pump won't stall out the prime mover
(electric or gasoline) by starting to pump until after the compressor
gets up to full speed - and is not out of lube oil. *(Safety system.)
If you see an oil pump and small pressure gauge on the end of the
crank opposite the pulley, possibly a small spin-on filter, and an
~1/8" oil line heading up to the heads, you have this.

* Oh, and copper head gaskets can be annealed with a torch to dull red
hot (double check that temperature before trying, it's from memory)
and reused at least once in a pinch. *But parts should be cheap and
easy, they do not make many radical design changes - the 2008 units
look a lot like the 1950 units. *If it ain't broke...

* That's it in a nutshell, and in English. *When you're done give it
back, I've got a hankerin' for walnuts... * ;-)

* * -- Bruce --

Bruce, that was incredibly helpful. Thanks. Since "it can't be
single cylinder and two stage at the same time" then I stand corrected
about it being one or the other. The data plate mentions so many cfm
at 175psi. The cylinder does have a secondary "protrusion". Maybe
this is the second stage piston. I was confused because it is so much
smaller.

V

On Mon, 6 Oct 2008 11:17:00 -0700 (PDT), Vernon
wrote:

On Oct 6, 12:54*pm, Bruce L. Bergman
snip
* * -- Bruce --

Bruce, that was incredibly helpful. Thanks. Since "it can't be
single cylinder and two stage at the same time" then I stand corrected
about it being one or the other. The data plate mentions so many cfm
at 175psi. The cylinder does have a secondary "protrusion". Maybe
this is the second stage piston. I was confused because it is so much
smaller.

V
The second stage is smaller because the volume was reduced in the
first stage.

Pete Keillor

On 2008-10-06, Vernon wrote:
On Oct 5, 10:35*pm, "DoN. Nichols" wrote:

[ ... ]


* * * *I see that you're posting from googlegroups,
and you should be warned that it can sometimes take several hours
between posting an article there and actually having it show up there.
However, the articles get to the outside world (where news servers work
properly) fairly quickly.

[ ... ]

Don,

Thank you for the gentle, tactful admonition about google groups.
This led me to noodle around a little about the issue.

The result is that I have only now learned that google groupers are as
reviled and belittled as PETA activists, tree huggers, and AOL users!

Holy smokes, batman! I didn't know!

Shouldn't that be "Holy guano"? :-)

What do y'all use? Specialty news readers?

Well ... my news reader is slrn -- which came into life on a
unix system. A quick look around Google shows that there are versions
of slrn compiled for Windows system. The first one which I found was
at:

http://foory.de/thw/slrn/windows/

Two different versions to choose from. There are probably others to be
found.

But while there are problems using a web browser as a
newsreader, your primary problem with things not showing up in a timly
manner are attributable to the Google interface itself, not your web
browser. I don't know *why* the Google interface shows articles from
outside a lot more quickly than those posted from within its interface.
It might be an intentional attempt to control spam posting from the
Google interface -- perhaps hold onto articles long enough to see
whether there is a flood in unrelated newsgroups before letting them
escape -- except that people on the outside see them failry quickly.

With a good newsreader -- or even with a browser acting as a
newsreader, you can connect to many commercial sites and some free ones
as well. The one which I use is newsguy (check out www.newsguy.com to
read about what they offer (including a Windows based newsreader free
for the download -- but I can't say what it is like, because I don't use
Windows for newsreading. My one token Windows box is so far behind on
patches that I would never connect it to the outside net -- just to my
private net behind a good firewall which keeps it from seeing the
outside at all.

Newsguy's prices are reasonable -- the service which I selected
started out at $9.95 per month, and then I picked up the once yearly
payment of $99.50 per year (I may have the last digits wrong). Since I
don't visit binary newsgroups, I never use my full bandwidth, and aside
from Newguy boosting the monthly bandwidth allotment for users who have
been on for a while, they also let unused bandwidth accumulate, so I now
have over 1.2 Terabytes of bandwidth available -- if I wanted to go wild
downloading from the binaries newsgroups. :-)

Others can point out other news servers, I only speak about what
*I* know. I used to have an ISP which gave me a true news feed so I
could run my own news server -- but they were bought, the new company
dropped the newsfeed, and then dropped their news server as well, so I
moved to another ISP with a T1 feed -- and they just dropped the monthly
charge by $200.00 for my last three-year contract. It is nice to have
that extra $200.00 per month for tools and other toys. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2008-10-06, Vernon wrote:
On Oct 6, 12:54*pm, Bruce L. Bergman
wrote:

[ ... ]

* It can't be a single cylinder and a two stage at the same time...

* Two stage normally implies a multiple of two (four, six, eight)
cylinders - and the second stage will be physically smaller. *Of
course, they could do something really odd like having three feed
two...

[ ... ]

Bruce, that was incredibly helpful. Thanks. Since "it can't be
single cylinder and two stage at the same time" then I stand corrected
about it being one or the other. The data plate mentions so many cfm
at 175psi. The cylinder does have a secondary "protrusion". Maybe
this is the second stage piston. I was confused because it is so much
smaller.

Yes -- that makes it two stage. That smaller cylinder allows
compressing air which has already been compressed once without having a
great deal of force on that connecting rod. As it is, I suspect that
the two cylinders need about the same force, so the crank is balanced.

I may be a bit late with this, because I was not able to get to
the newsreader last (Monday) night before I went to bed.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 8 Oct 2008 00:20:25 GMT, "DoN. Nichols"
wrote:
On 2008-10-06, Vernon wrote:
On Oct 6, 12:54*pm, Bruce L. Bergman
wrote:

* It can't be a single cylinder and a two stage at the same time...

* Two stage normally implies a multiple of two (four, six, eight)
cylinders - and the second stage will be physically smaller. *Of
course, they could do something really odd like having three feed
two...

[ ... ]
Bruce, that was incredibly helpful. Thanks. Since "it can't be
single cylinder and two stage at the same time" then I stand corrected
about it being one or the other. The data plate mentions so many cfm
at 175psi. The cylinder does have a secondary "protrusion". Maybe
this is the second stage piston. I was confused because it is so much
smaller.

If you are seeing a 175 PSI output, it HAS to be two stage.

As a practical matter, 125 PSI is about all you can get in a single
stage shop air compressor without building it solely for high pressure
and getting very poor CFM volume output.

Really high pressures like filling scuba tanks are 4 or more stages,
they keep boosting the pressure in increments till they reach the
target.

Yes -- that makes it two stage. That smaller cylinder allows
compressing air which has already been compressed once without having a
great deal of force on that connecting rod. As it is, I suspect that
the two cylinders need about the same force, so the crank is balanced.

That, and the two crank throws (and therefore the pistons) are
usually out of phase with each other on purpose, so the first stage is
on the exhaust stroke into the intercooler at the same time as the
second stage is on it's intake stroke. Just enough time for the air
to dump some heat on the way through.

-- Bruce --