Direction of AC motor not reversing (single phase)

Thread Starter

Canobi

Joined Mar 4, 2015
29
Hi guys


I recently started putting a home machine shop together and had to take a crash course in ac motors after the ones on the lathe and mill packed up (both machines are old and I'm in the middle of referbishing them). The mill uses an intersting type of motor which has a mechanical soft start and some kind of centrifugal switch. The problem is that the replacement motor spins in the wrong direction and I can't get it to go the other way, no matter what I do with the internal connections.

I took a pic of the terminals and labelled them for clarity before I started swapping things around, if anyon has knowlege of such motors, I'd be most appreciative for any assistance in getting it to spin the other way.

 

MaxHeadRoom

Joined Jul 18, 2013
22,886
When you say 'Mechanical soft start' do you mean internal or external to the motor?
How do you know it has a centrifugal SW? Normally these are on the motor shaft and not visible, also a external capacitor is used if this is a cap start induction motor.
Can you show a pic of the motor data plate.
Max.
 

Thread Starter

Canobi

Joined Mar 4, 2015
29
I believe it is internal (most probably to do with a primary/starting coil if I have things right).

It's fair to say I'm not 100% on whether the motor in question has a centifugal switch or not, I was going by the old one it was supposed to replace which is the practically the same type. That one had a very distinctive noise when the switch closed (sounded like some kind of spinning ratchet mechanism) but this new one is one of the quietest motors I've ever come across when running so its hard to tell.

The motor doesn't have or need a cap, neither of them has one, just wire a plug to it and away you go.

Here are some pics as requested:




 

MaxHeadRoom

Joined Jul 18, 2013
22,886
That is an oldie!
It sounds like a repulsion-induction motor, in some cases the brushes lift after it gets up to speed.
I will check my old re-winding book of the same vintage.!
Is that an opening in the end bell that you can take a peek?
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
22,886
I confirmed that one method the repulsion-induction method uses is a centrifugal method to lift the brushes off of the com when run speed is reached.
Most of this type require the brush holders to be moved to a different angle.
IOW there is a FWD/REV position on the brush holder. If this is the type of motor.
Max.
 

Thread Starter

Canobi

Joined Mar 4, 2015
29
There is a big hole but you can't see much inside through that one, a smaller one adjacent was better, though I needed to find a torch small enough to get light in there to take pics. That being said, there's not that much to see:


 

Thread Starter

Canobi

Joined Mar 4, 2015
29
I agree, it's a bit dirty inside, I'll brave it and see about a clean up and repaint in the near, I'm still no me the wiser on getting to spin the other way, though it may become apparent when I take it apart.
 
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