Need help getting motor to spin

[ARC-170]

I have an older motor to an Atlas Craftsman lathe. When I hook it up, it just hums (and the lights dim a bit), but I can get it to rotate in either direction with a little twist of the shaft. What am I doing wrong?

I can switch it off and on when the shaft is turning (either direction; it just needs to be moving) and it works fine.

Here's a picture of the hook-up. It goes from the motor wire to red wire nut, to switch via red wire , then switch to black power cord wire via another red wire. The other motor wire goes to the white power cord wire. The ground wire on the power cord is not connected.


Here's a picture of the motor plate. I'm not sure how old it is, but it's made in the USA:

 

[Jim F]

Start cap.

 

[Ulma Doctor]

faulty start cap, faulty wiring, or faulty centrifugal switch are all possibilities

 

[markba633csi]

Ulma is correct the start circuit is faulty. If this motor has a start capacitor then that would be the primary suspect, followed by the internal centrifugal switch.
However your motor might be a "split phase" type with no capacitor. In that case, the internal switch may be the culprit, either worn out or broken.
Worst case the start winding in the motor is bad, and there is little you can do unless there is some obvious visual bad connection at the lead-in wires.
-Mark
ps a small number of motors have a flat capacitor hidden in the base. These are not available new anymore. Most folks add a external round cap and run wires in. There is also a solid state solution. Mike did a posting about this on one of his motors

 

[ARC-170]

I got it! There are two screws sticking out in the connection box. These connect to some sort of centrifugal switch. Not sure if that's what it is, but I'm taking a guess based on what you have all told me so far.
The wires coming in from the motor (the old cloth-covered ones) need to be connected to these. I then wired it up like normal with the switch, etc.

Worm's eye view:
I lifted the end cap enough to shine a light and take a picture. The two wires you can see go from the centrifugal switch to the silver studs on top.


Bird's eye view:
Here are the two studs on top:


I'm glad it was just a connection issue and not something more serious.

The PO had this wired to a reverse switch that was mounted to the table the lathe was mounted on. I had to cut everything to get it off. The wires were crumbling and I unhooked everything so I had no reference. The MOLO wiring diagram didn't apply, either.

Thanks!

 

[markba633csi]

Glad you got it!
-M
We are the motor champions, my friend
And we'll keep on wiring, till the end