# I ride the Air compressor short bus



## Joe Stolz (Apr 21, 2019)

Hello, I found an old laydown compressor. I've been wanting a slow rpm unit that will last for years. My issue is I have a knowledge void on compressors maintenance and repair. Here is what I have it runs on 220 or 110, I do not know what oils to use when to oil electric motor or how often. I need to learn how to make sure the cut-off switch is working and any other knowledge I should have to keep this in good working order* you for your help Joe*


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## stevon (Mar 5, 2019)

Joe,
Do you know the history of this compressor? was it run recently? [Disclaimer] I would not attempt this for anyone who does not have mechanical and or electrical experience! I would start by turning the compressor by hand to see if there is any binding, screeching or any obstruction to rotating the pump 360 degrees. next would check motor the terminal wires on the motor for shorts to ground. To check the winding's resistance see https://www.electricalengineeringtoolbox.com/2015/12/how-to-test-and-check-single-phase.html. If they check out next wire the motor for your desired voltage, I recommend setting the motor to 240 volt at the 12.4 amps. At 120 volts and 25 amps it is hard to find a plug and socket rated at 30 amps 120 volt plus 240 volts is more efficient anyways. Put a couple of drops of 3-IN-ONE SAE 20 motor oil in bearings, check to see if pump has correct level of SAE 30W non detergent oil. Next "tap" tank with something metal around the bottom of the tank to see if it sounds "tinny" and look for any obvious signs of corrosion coming through (holes) check to see if you can determine if there is water sloshing in the tank. Leave the bottom drain open to test compressor at first. DANGER if you have any doubts about the tank corrosion/integrity do not pressurize it! Have it professionally tested or just replace it. next wire power into pressure switch then run the compressor. you should hear air blasting out the bottom. Close drain valve and If you are 100% sure the tank is good you can pressurize it from a safe distance 10 feet or more (do not stand close or observe compressor being on top of it). Make sure you can manually shut of power remotely at any point eg. unplug/ turn off breaker away from compressor! Also a hose to bleed off air pressure remotely I would stand back and run compressor to 175 psi and let the pressure switch disconnect motor, more PSI than that I would bypass pressure switch and manually disconnect power, lower (back off) setting on pressure switch, bleed off 50 lbs, try again. Once test is done make sure check valve and safety over-pressure relief valve are in good working order. Replace the pump oil with SAE 30W non detergent oil
Warning! Do this at your own risk, with safety equipment such as goggles, headphones, etc. defer to an expert if at all possible. Good luck!
Stephen


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## Osviur (Sep 7, 2015)

Joe,

Just an observation about the resistance test. It seems that your antique Wagner motor is a kind something different to the modern motors found usually in the market.
This Wagner motor doesn't use a capacitor to start or a shaded pole. I t seems to be a repulsion start - induction run, If it is so, inside the motor you will find a wound rotor with a commutator, as those used in the DC motors, a set of brushes and a centrifugal mechanism to lift the brushes and close a collar around the commutator to short all the segments, converting the rotor in a kind of squirrel cage of a induction motor.
At the start, it uses the rotor as an DC armature, but fed with the inducted voltage in its wound rotor and shorted by the brushes. There is not an electrical connection with the external power. Near the full speed, the shorted commutator transforms the motor in an induction one.
The advantage: High starting torque (2X -3X) with just double starting current.
All this mechanism is very complex and delicate. I would recommend not to try to disassemble.
In accordance with the plate's diagram this motor is wired for 110 V. , two windings in parallel. 

Regards


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