RB wrote:

Compressor is an older Champion roll-around.
Tank is about 10-15 gallons, compressor is a vee-twin, old U.S.-made
I just put a new pressure switch on it, only to find the motor is bad.
That motor was not original. I believe the original motor was 115V, HP
unknown.
What should I look for in a replacement motor?
I prefer to stay with 115V.

I tried a 1 HP motor that was wired for 115V, and it was not enough -
stalled and tripped the circuit breaker.
How do I determine what HP it needs?

There are several factors to consider, the first of which is the maximum
rpm that the pump can run. The motor speed and the ratio of pulley sizes
will determine that. With a lower rpm motor the pulley ratio will have
to be changed so the motor is not overloaded. If you put a smaller
pulley on the 1 hp unit it might have turned the pump but at a lower
speed.

The ideal ratio is one that the motor is drawing the rated amps at the
full pressure setting of the pressure switch. With a larger motor,
there is more power to turn the pump faster and produce more air.



John