Speed up air compressor

[ijroorda]

I picked up an air compressor this weekend; $75 on Craigslist. It's got a 30 gallon tank and a 1HP motor. As best I can tell, at least the tank is a Johnson brand; the data plate seems to indicate it was manufactured in 1961. I can't find a brand name on the pump; it has a plate that says "Model A-4" and "2-1/2 x 2-1/2". It looks like a one-lung pump with a fairly long stroke. I forgot to take pictures while it was light out but I'll try to get some tomorrow.

It works fine, but it's a little on the slow side - at least that's my gut feeling, I haven't timed it. The motor is rated for 1725RPM and has a 3" pulley on it; the flywheel on the pump is 11.5". With the limited information I've provided, what would be the ramifications of spinning the pump a little faster? A 4" pulley on the motor should give me 600RPM at the pump; a 4.5" pulley would give me 675RPM. I assume the motor would draw more current with a bigger pulley, which might be a problem since the garage at my rental house only has one 15 amp circuit, but would I also be in danger of destroying the pump?

Thanks for any information you can give me; I'll get some pictures tomorrow.

 

[1984Datsun]

Sounds like a better thing to do is upgrade the motor to a 2 or better yet, a 3 hp...

I would then run a 4.5" (2hp motor) or 5.5" (3hp motor) pulley. That's only if the new motor turns the same as the old one. If not, new calculations will be necessary... I am not entirely confident that a 1 hp motor is going to be strong enough to keep turning the crank at higher compressing pressures...

Best question here... how long does it take to fill the tank from empty? Is the tank water free, or is it half full of water? (my old one was half full, and it still took an insane amount of time to fill up...)

Make sure the bearings on the pump are good, and maybe pull the head/clean it up/check other stuff over a little before you even drop money on a bigger motor, just to get an idea of what it can run at. Don't worry about pulling the bottom end apart, just change the oil and turn it over by hand with the head off and check the piston's movement. It would be pretty noticeable if a bearing is bad or the connecting rod end cap is loose, etc.

I'm fairly sure the motor on your compressor may have been replaced at some point.

My old 25 or so gallon compressor had a tiny 3/4 hp motor spinning a twin cylinder pump... talk about slower than hell and an insanely long time to full tank, like 20 minutes. The original 3hp motor burned out... 3/4 went in...

I wouldn't spin that pump faster than maybe 800 rpm. Remember, the faster you go, the louder it gets, and the less time it'll last.

Whatever you do, I'd keep the pump and tank... definitely good stuff. The motor probably could use replacing with a more powerful one to increase rpms and reduce the tank filling time.

Let us know how it turns out!

 

[kams1973]

An A-4 is a single cylinder Quincy pump. Find the pump specs and go from there.

 

[ijroorda]

Thanks for the input guys, especially for the ID on the pump. I did some more looking and came up with some more info on the pump. Looks like the RPM range is 400-700, according to a Quincy parts book; I also found this info on another forum:

From Quincy catalog No. 6600-1. The A4 is a single cylinder.

1/2 hp yields 1.56 cfm @ 100 psi @ 400 RPM.
3/4 hp yields 2.46 cfm @ 100 psi @ 630 RPM.

Doesn't look like I'll make a speed demon out of it, regardless of what I do. Based on the info above, I might try a 4.5" pulley and shoot for 675RPM with my existing motor. If I need to upgrade the motor, I can't go bigger than will run on the 110V 15A circuit in my garage, so 1.5-2HP is probably the absolute max for now.

Tonight I'll get some pictures; I'll also double check that the tank is water-free and time it from empty to 100psi (current cut-out pressure). The tank is marked for 160psi; any guesses on how high I could reasonably expect the compressor to go?

 

[1984Datsun]

I'm sure the compressor will fill that tank to at least 130 psi. Maybe 140-145 if it all works right.

Quincy... that's what popped into my mind... they are known for the real slow pumps that make nearly no noise...

Sounds like you're going in the right direction... can't wait to see the results!!

 

[kams1973]

I'm not sure why Quincy rated their older single stage pumps for only 100psi. You should be able to run 115-130psi w/ no problems.

 

[plinker]

You really dont want the pump going any faster then it has to as speed can/will wear it out faster.

If it takes way longer then it should to build air, that could mean rings or valves are worn, from what I know.

Most small compressors usually run about 125psi when it kicks off, I dont see whay it would be a problem as long as the tank is rated for it.

 

[larry_g]

Thanks for the input guys, especially for the ID on the pump. I did some more looking and came up with some more info on the pump. Looks like the RPM range is 400-700, according to a Quincy parts book; I also found this info on another forum:

From Quincy catalog No. 6600-1. The A4 is a single cylinder.

1/2 hp yields 1.56 cfm @ 100 psi @ 400 RPM.
3/4 hp yields 2.46 cfm @ 100 psi @ 630 RPM.

Doesn't look like I'll make a speed demon out of it, regardless of what I do. Based on the info above, I might try a 4.5" pulley and shoot for 675RPM with my existing motor. If I need to upgrade the motor, I can't go bigger than will run on the 110V 15A circuit in my garage, so 1.5-2HP is probably the absolute max for now.

Tonight I'll get some pictures; I'll also double check that the tank is water-free and time it from empty to 100psi (current cut-out pressure). The tank is marked for 160psi; any guesses on how high I could reasonably expect the compressor to go?

By the numbers you posted your limited to 700 rpm. If a 1hp motor will spin the pump at 675 and not overcurrent before reaching cutoff going to a bigger motor is going to gain you nothing. When you start pushing an old single stage beyond 125psi you are pushing it. Heat starts to build and the amount of additional energy into the tank diminishes greatly.

lg
no neat sig line

 

[malibu101]

I have seen quite a few Johnson compressors. Many years ago building HVAC was controlled by pnuematics. Mostly by a company called Johnson Controls although many manufacturers at the time made products for use with pnuematic controls. And some still do, the systems are still out there in use. I regularly work in old buildings that use these systems or remnants of it, hence why I've seen many Johnson labeled compressors.
Most of the compressors designed to be used with a pnuemantic HVAC systems are designed to run at a relativly slow speed and not make much CFM but run almost constantly. And I see many (regularly maintained) that have been running for many years.
After all this rambling, my opinion is don't expect too much out of this machine. And if you try to speed it up I fear your thought of destroying the pump may become a reality.

 

[Danglerb]

My vote, don't screw with it. Be sure you understand how all of it works before screwing with it, if you decide to screw with it anyway.

 

[TireTracks]

It's not going to be a speed demon, but atleast it will be more pleasent to listen too while it fills compaired to a newer high speed pump.

 

[1984Datsun]

It's not going to be a speed demon, but atleast it will be more pleasent to listen too while it fills compaired to a newer high speed pump.

And you can at least chat with someone for a few minutes while pressure builds...

You can't do that in the same side of the barn that the Husky 60 gallon is residing in, unless it's off, of course... it is loud. Not too loud, but loud enough that conversation is basically unfeasible and inconceivable...

So... while that old thing's filling up, go ahead and work on something else.

Or if you want, you could plumb in a small oilless compressor, or another one of those old compressors into the system. As long as you are still using the same tank capacity, it'll fill up about twice as fast. It'd be a dual pumps on a single tank set up... (AKA duplex) each powered by their own motor.

Kinda like this big freaking Saylor-Beall... only on a smaller scale...

Since your compressor is meant to run all the time, I'd just plug it in and let it fill up and keep itself full.

Don't modify it... just run it.

We all now know its true original use, which is run all freaking day long...

Just let it run all day long with short breaks, and you don't really have too worry much about those pesky air line leaks now, do you?

On a separate note, I bet all of us could use a Saylor-Beall like that one pictured... 5hp, 80 gallon tank, and 34.6 delivered CFM at 175 psi...

 

[ijroorda]

I timed it tonight; from 0-100psi took approximately 10:30. I bled it down to where it kicks back on at 75psi and it took about 2:35 to pump back up to 100psi.

Here's a picture of it:

I didn't get a picture of the tank plate; it was against the wall and I couldn't really pull it out - there's an immobilized truck in the way currently.

I'm going to change out the pressure switch to a 125psi model and see how it does, since the unloader is leaking a little bit anyway. Other than that, I probably won't mess with it much for now. If I can regulate it to 90psi and run an impact without having to wait on it too much, I'll be happy. It's definitely nice and quiet, which is a plus since I live in town with neighbors on all sides.

Thanks for all the info and advice.

 

[1984Datsun]

That thing looks cool!! I like the flywheel on the pump... just round holes in it... classy...

Those times aren't too bad. My old compressor was much, much worse.

 

[malibu101]

Yep. Looks like many I've seen.
You're gonna make that sucker work real hard to go to 125. It will but it's not made for that pressure. They normally have a no more than an 80 cutout.
The pnuematic HVAC controls that it originally ran has maximum feed pressure regulated to 20. trying to use any type of air tool with this will be taxing on both you and the compressor.
I'm not trying to be downer but I know what these are. They are real good at their intended job but I fear you have too high expectations for what this can put out. It will power an impact but after removing one wheel you'll probably notice the loss of air pressure.

 

[ijroorda]

I'll bring this thread back from the dead to give an update. I decided to go ahead and risk shortening the compressor's life by putting a 125psi pressure switch on it; it's still working for me almost two years later. It's still slow and I wouldn't try to run a die grinder or DA with it, but it more or less keeps up with my wrenching pace running an impact gun or air ratchet. I'm not a heavy user of air tools, so hopefully it will last until I have a real shop and can get a real air compressor to put in it. Either way, this one doesn't owe me much for the $100 or so that I've got in it.

 

[Jakwagun]

Found your thread on a Google search. I cannot seem to identify the pump I just acquired, but it seems it's the same one as in your picture on this thread.
Hoping you might be able to let me know if you found out what yours was and if you knew of any parts/manuals links or locations.
Thanks!

 

[jerrdanjohn]

I have two of them compressors. They are Quincy but not sure of the model they are 2-1/2 bore and 2-1/2 stroke. I used one to build into an engine for a board track racer and am building the other into a hit and miss engine.
Here's a link to the youtube video of the one I made into a engine.

Not sure how good they are for actual compressors, but they make great engines.

 

[kams1973]

I have two of them compressors. They are Quincy but not sure of the model they are 2-1/2 bore and 2-1/2 stroke. I used one to build into an engine for a board track racer and am building the other into a hit and miss engine.
Here's a link to the youtube video of the one I made into a engine.

Not sure how good they are for actual compressors, but they make great engines.

Awesome video. You need to start a thread detailing how you did that.

 

[ijroorda]

I finally retired this compressor from service in my garage. The tank had developed a pinhole leak, so it was time to quit. Never did kill the pump running it to 125psi the last 5 years.

I was planning to replace it with an older Dayton Speedaire compressor (27gal or so) that I traded a table saw for, but it turned out that tank leaked too. My friend picked up a 30gal compressor at an auction because he needed the motor; he gave me the tank, I swapped the Dayton pump and motor onto it, and I'm back in business for the cost of a few fittings.

So, now I need to figure out what to do with the old Quincy pump. It's kind of a cool unit; I'd hate to just scrap it, but I don't really need to keep it around either. Maybe jerrdanjohn needs another engine project...