Compressor Motor Starts to kick out.

by Shane Stewart
(Mt. Zion, IL USA)

I have a Sanborn 60 Gal. 5 Hp. Single Stage Compressor. It is fed by a 220V Circuit on a 50 amp line. (Tied into my welder circuit) it has a thumb-pressure style reset switch on the motor.

I have also rebuilt the entire Compressor Head with new reed valves, seals, gaskets and such with the upmost respect to ensure everything was built cleanly and with respect to not getting any dirt in it.

I also put new rings on the Pistons and gave the cylinders a quick hone as you would when rebuilding a car engine.

My problem arrises whenI start it up as it will only build 50 psi before I can hear the compressor motor start to cycle between what appears to be a ramp up cycle and a run cycle (Compressor has 2 capacitors) and I have also had my buddy check out the capacitors as he runs a shop that rebuilds all of this stuff all the way to 4000 HP. monsters. as it starts to cycle back and forth finally it will kick out the thumb pressure switch. was I wrong to hone out the cylinders? or is my problem elsewhere?

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Bill says....

Does the problem occur if the welder is running or even when it's not?

I'm guessing that you may be getting some sort of voltage drop, the motors cycle to inrush from the capacitors, and if there's not enough power the in-line breaker pops as it's trying to pull too many amps.

Or, the motor could be failing. Can you get your buddy to do an amp test on the motor to see what it's drawing?

Bill