Alternative motor?

wa5cab said:
..., the centrifugal switch is probably stuck open.
Click to expand...

Yes, that's the likely case. I've pushed a chopstick between the slots to reseat such a switch, but usually
it's better to pull the bell housing off (after dismounting the motor...), and burnish the contacts.

If there were a capacitor, it would have been noted on the dataplate; no mention of uF, so the start
mechanism has a centrifugal switch and the 'hum but no spin' symptom usually means
dirty contacts (sawdust?).
 
Well, I am befuddled....As suggested I turned on the motor and spun the pulley by hand. Sure enough, it starts to spin up, but very quickly the switch clicked and it coasted to a lower rpm then clicked again spins up, switch clicks, coast down and so on, but never reaches full speed. I pulled the bell end off and inspected everything. It's very clean inside, no signs of arcing anywhere. The centrifugal switch moved freely. Points were ok, but I cleaned them up a bit. I put some lube on the centrifigal switch. Put it together and symptoms remain the same.

IMG_1266.JPG

IMG_1267.JPG
 
Is there one or two caps, sometimes the start and run caps are in one case sometimes they are separate, does the cap have 4 leads or only two. The runswitch could also be changing to a different set of windings, as well as cap.
You say it runs up, then click and slows down , then click, and speeds up again, then click and slows down. Sound like the start windings and cap are ok but the run windings/cap are not. the switch appears to be switching.
 
Yes it sounds like an open run winding or connection to it. It starts with help on the start winding, switches off the start > slows down until the switch closes again and repeat.

David
 
David S said:
Yes it sounds like an open run winding or connection to it. It starts with help on the start winding, switches off the start > slows down until the switch closes again and repeat.

David
Click to expand...

And you are the winner! I decided to give it up and take it to the motor shop tomorrow for a fix or replace decision. As I pulled the wiring apart to remove the cord I saw it- a yellow wire was laying loose, not attached to anything. Further inspection revealed it have arced or burnt or something to cause it to come loose from the post it was originally attached to. The post was toast as well. So, I installed a new screw/post and refastened the yellow wire and all is well again in my shop! Many thanks to you all. Your advice and input caused me to think it through and with some dumb luck, solve the riddle. All is well!!
 
David, you are the winner! I looked closely at each wire and discovered this yellow one loose and not attached to anything. The post it had been attached to was burnt and the wire had broken off from the ring attaching it to the post. A new screw/post and wire end and all is well. The advice here made it possible to save the motor and continue the use of the lathe, at no expense! Many thanks Gentlemen!!

IMG_1268.JPG
 
Glad that it all worked out. Others were homing in on the same conclusion.

David
 
OK. Glad that you found the problem. New motors aren't cheap.
 
You must log in or register to reply here.
Back
Top