picked up a small compressor today

[jake00]

found it on CL

the motor is a 1hp baldor, the pump is a gardner denver.

it works, but once the pressure drops, it tries to start but cant, I dont think it has a check valve. (that would cause this right?)

other than that, I'm planning on this replacing my 5.5hp (yea right) oiless crapsman....

 

[goodfellow]

I've looked at many compressors over the years, but have never seen that design or quite that configuration. It's stationary, so are there any other markings on it? Judging by the piping, it could be a "homebrew" design.

 

[Ray-CA]

I had one very similar to that one. It was able to be switched between 110/220 but the directions were missing so I kept it on 110. It worked great for years until I got a larger unit. I think I gave it to one of my buddies that was going through a divorce and his wife had all his stuff stored until the divorce was settled. He still has it and it's going strong.

Ray

 

[Matti]

it works, but once the pressure drops, it tries to start but cant, I don't think it has a check valve. (that would cause this right?)

pressure switch? There should be a check valve threaded into the inlet port of the tank.

 

[Uncle Buck]

found it on CL

the motor is a 1hp baldor, the pump is a gardner denver.

it works, but once the pressure drops, it tries to start but cant, I dont think it has a check valve. (that would cause this right?)

other than that, I'm planning on this replacing my 5.5hp (yea right) oiless crapsman....

Don't get hasty unloading that ol noisy direct drive just yet. I suspect this old timer will not push as much air as that Crafty you hate. This is a cool looking setup I would not mind owning myself, but just make sure it will deliver to your expectations. You don't want to find out after the fact you made a mistake! (I think it is a home made set up due to the additional matierial used as a mounting platform. Good luck

 

[Torque1st]

I agree it looks like a homebrew. It may have "worked" at first but the start cap lost some capacity. It needs a check valve and a head unloader to work reliably.

 

[bb1970]

Don't get hasty unloading that ol noisy direct drive just yet. I suspect this old timer will not push as much air as that Crafty you hate. This is a cool looking setup I would not mind owning myself, but just make sure it will deliver to your expectations. You don't want to find out after the fact you made a mistake! (I think it is a home made set up due to the additional matierial used as a mounting platform. Good luck

I agree. I got a deal on a little homemade compressor. Just for the house garage. Worked ok for a little while. Then would hardly pump at all. It was a Bostitch oilless on a 10 gal. tank. Cool set up but age and abuse finally caught up.

 

[jake00]

where's the best place to get an unloader and check valve?

I don't do much with air, the occasional impact gun usage , some tire filling, some brad nailing

 

[Torque1st]

It may already have an unloader built into the pressure switch assy. A check valve can be purchased at many air compressor supply houses. The check valve often has a connection port for the unloader. The pictures are too small to see much.

 

[jake00]

I'll snap some more

 

[Torque1st]

I am not familiar with that particular pressure switch. Someone here may be familiar with it. It looks more like an industrial control rather than a pressure control for an air compressor. Air compressor pressure switches usually have the built in unloader function.

 

[jake00]

Here's what I think I want to do

plumb in a few coils of copper into a check valve, but I want to put it into the tank right where the gauges are. I'll move the guages/air hookup over to where the pressure switch is. I also have to change out the pressure switch cause, what I have is some sort of industrial differential, with no unloader on it. Then I plumb the check valve to the unloader right?

 

[jake00]

Any idea what the brass piece is on top of the grey guage?

 

[Uncle Buck]

Just keep in mind, the critical figure is not the max PSI output, but rather Cubic Foot Per Minute delivery CFM at around 100 PSI or greater. Also never forget to factor in the pressure drop from the pump to the tool through the lines and hose.

 

[Uncle Buck]

Any idea what the brass piece is on top of the grey guage?

No claims as expert here, but I think that is the adjustment for the air cut off at the upper limit on the control (Oh yea, been wrong too many times in the past, but I think I have this one right)

 

[jake00]

CFM at around 100 PSI or greater. .

is there a formula to figure that out? I know the bore, sttroke, and rpms

 

[327-365hp]

I bought a new pressure switch for my twin stack at Graingers.

 

[Uncle Buck]

is there a formula to figure that out? I know the bore, sttroke, and rpms

No doubt there is, I am sure the pulley diameters are also an important factor as well. I will admit though that I do not know what that formula is, or how to establish the CFM delivery. I hope some bright guy that knows a lot shows up to lend a hand soon, I am about tapped out.

 

[Torque1st]

Any idea what the brass piece is on top of the grey guage?

Probably the safety valve for pressure relief. Does it have little holes in the side?

Pick up a compressor pressure control at a compressor supply house. Grainger, McMaster Carr, Tractor Supply, etc. They are sized for the motor HP and supply voltage. You can probably get a check valve at the same place.

If you are handy with math you can calculate your approximate SCFM by knowing the compressor bore and stroke along with the motor speed and the pulley diameters. When you have all of that figured out take about 75% of that figure to allow for volumetric efficiency. The result will be a rough approximation of the compressor output if it is in good condition. Your compressor will have a vary small output but it will fill tires and run an occasional air tool briefly.

Also test the tank before you pressurize it the first time. You can do it yourself if you are handy and trust yourself or you can have it tested. See the thread here:
http://www.garagejournal.com/forum/showthread.php?t=33526

 

[tatra]

show a pic of the guts of the pressure switch........reminds of the type used on locomotives but thats the sparky's dept........rrmech?......any thoughts?

 

[back2class]

Capacitor. My guess is the start capacitor is shot.

 

[Mezzanine]

Capacitor. My guess is the start capacitor is shot.

I agree. Check valve wouldnt keep the motor from starting up... Either the motor is undersized for the pump, or the "starter" or capacitor is shot. My compressor did the same thing- I pulled the cover and discovered that the wiring on the capacitor was loose. Fixed that, and it started right up.

 

[Torque1st]

I agree. Check valve wouldnt keep the motor from starting up... Either the motor is undersized for the pump, or the "starter" or capacitor is shot. My compressor did the same thing- I pulled the cover and discovered that the wiring on the capacitor was loose. Fixed that, and it started right up.

I beg to differ, a bad or missing check valve WILL prevent the motor from starting even with a properly sized motor. When full back pressure is on the compressor the motor may hum and let the smoke out which is bad. I have had this problem on an old compressor with a leaking check valve.

I have also had bad start capacitors. The OP stated that the motor WILL start with NO pressure in the tank. A bad or disconnected start capacitor would prevent the motor from starting even the first time much less under pressure.

It is possible that a capacitor that has lost some capacitance due to age etc could cause the motor to start with NO pressure but fail to start WITH pressure. However a properly designed and set up compressor WILL have a check valve.

 

[Mezzanine]

Torque, Point taken, you could be right... I agree with you that a compressor will/should have a check valve... I suppose a check that failed open could cause difficulties for the motor on start-up; wouldn't the tank slowly leak down through the compressor though? I suppose that would depend on the condition of the compressor, of course. If the check failed closed, then I think the motor would start, but pressure would build rapidly, forcing the check open, or stalling the motor.

When I had the problem I described with loose wiring, it would start when the tank was empty, but not once there was any significant pressure.

Hmm... Could be a combination of problems?

 

[Torque1st]

With a bad check the tank will slowly leak down past the compressor rings. You can hear a hiss and sometimes see oil bubbles around the oil dipstick.

When I rebuilt my check valve on the unit I have presently I had the wrong seal material in it at first. The heated air caused the check valve to stick closed on restart. It damn near stalled the motor out before it "popped" open.

The motor on most compressors is sized to just have enough power to turn the compressor over while pumping at max pressure/load. A properly sized motor will start a compressor under no load but will not start a compressor under load. Hence the need for an unloader valve on most compressors.

The OP's unit has no check valve nor does it have a pressure release. It needs a bit of work to make it run. The parts are readily available. The motor on the OP's unit may be oversized enough that it would barely restart. The person that had it may have never had it running for a restart either.

BTW, I build my own compressor systems. I don't buy them. I can't stand to buy something that has been designed by an accountant and that I would have to rework right out if the crate to make it right. I look at the systems for sale at many of the tool stores and home box stores and just laugh at the shortcuts the accountants have made to cut costs. I have rehabbed a few like the OP's unit just for fun and something to do and given them away. I have the parts to make another system sitting in boxes at the moment.