Lathe Reverse

**m_c** · 28-04-2020

There are 3 variations of common induction single phase motors.

The fact you've only got one capacitor rules out the Capacitor Start / Capacitor Run option (provides the best of both options below)
You say you don't hear a click, which likely rules it out being a Capacitor Start motor (gives more starting torque, but adds the complexity of a centrifugal switch)
So it's likely you have a Capacitor Run motor (gives very little starting torque, but helps the motor run a bit smoother)

They ultimately all work in a similar way, with a second (usually weaker) winding, that uses a capacitor to create a delayed phase, otherwise the motor will simply vibrate between poles when you apply AC power.
The bigger the capacitor, the more power the second winding gets (more starting torque), but the more the windings will heat up due to the relationship between the power, the motors inductions causing the windings to essentially fight against each other (hence why a Cap Start motor relies on a switch to disconnect once running, otherwise the motor would overheat quite quickly).

You just need to move the capacitor's position so it creates the delayed phase in the correct direction, but I can never remember the connections.

**blackburn mark** · 28-04-2020

Originally Posted by m_c

There are 3 variations of common induction single phase motors.

Most of that is rocket science to me... I get the general, gist I think.

I am running on the deduction that IF cap on pin2 = Forward and the cap on Pin4 = Reverse then the bus bars cannot be jumpered twixt Pin2 and Pin4 for reverse because that would eliminate any need to swap the cap from Pin2 to Pin4 so I have been unknowingly / randomly jumpering pins via the tumbler switch until I hit (1<----->2) + (3 <------> 4) where it will run in either direction depending only on the capacitor placement.

Having said that, I was 99% sure I had cracked the problem earlier and I was wrong so I'm going with 98% this time