Question about lathe stalling

That missing part is what shorts out the commutator to allow the motor to run as an induction motor once its up to speed. It looks like yours doesn't lift the brushes when it reaches operating speed. So it can continue to run as a repulsive motor as the commutator never gets shorted.

Greg
 
The picture of the nameplate is a little washed out from light. Does that tag say type "CU"? It's also odd that the tag tells what leads to change for rotation, but not for using either 110 or 220 volts??? There are a lot of different configurations for these old Westinghouse motors. My ARS repulsive motor did not have a shorting mechanism. Maybe that's the difference between a type AR and ARS??? Not sure, but interesting none the less.

So far, I have not been able to locate any info on a type "CU" Westinghouse motor, but I am interested in these older devices and will continue to look when I have time.

In the end, if you do end up replacing the motor, you may want to change your pulley size if you want to keep the speeds the same since this is a 1140 RPM motor. I had to replace the motor on my South Bend a few months back and found a great deal on a 1-1/2 HP at Surplus Center. Shipping seems high but the price was dirt cheap and it is a very nice motor. So, overall, the price was very good for what I got.

Good luck,
Ted
 
The tag does say CU, sorry about the light. I was thinking about the pulley size too but the one that's one the motor is very small, maybe only 2 1/2". I imagine I can go down a little but not much.

I dug through my stash and found 3 motors. One is 3400rpm so it's out.

The second is below. It's 120/240 but no plate to show how to wire it for each. The switch on the side only switches one wire and there's only two wires coming out of the box so I guessed it was wired for 120 so I hooked it up and it came right on. I'd rather 240 so I could use the existing wiring in the lathe but no clue how to wire the motor for that. It's also not a reversible motor but I think I could live without that. I can't think of a single time I ran my smaller lathe backwards. Good to know I have a good motor for something else when the need arises.

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The third motor I have is also a repulsive/inductive motor. I had no idea I had it. Anyway, it's also 120/240 and again only 2 wires coming out so I guessed 120 and wired it up. It came on and I could hear the switch when it came up to speed. Pretty cool. There's only 4 wires coming into the box. Wish I knew more about motor windings and stuff like that. Regardless, this one spins the wrong way so can't use it on the lathe but I have a power hacksaw that the motor just went out on so maybe it'll live there. Would be nice to verify it's actually wired for 120 before I use it long term though. Anyone know a good way to do that?

Looks like I'm in the market for a motor :(.


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Interesting stuff, Did some more reading and your right Ted some don't short the commutator. They're a repulsion inductive motor, the repulsion windings stay energized but produce very little torque at synchronous speed, there is a second winding on the armature that makes it a squirrel cage motor producing the majority of the torque at speed.
The repulsive start / induction run that Im more familiar with short the only winding on the rotor.
As far as reversing a repulsive start motor I understand its done by moving the brushes around the commutator.

Greg
 
Interesting, the motor from the lathe had a tapped hole at every 90º so the plate that holds the brushes could be indexed. The plate only had one hole to bolt through. Looks like it could be indexed possibly to change direction.

The century motor (the one that's spinning the wrong way for me) has a bolt on the exterior of the motor that connects to the plate that holds the brushes and it's at the far end of a slot that goes about 1/6 the way around the motor. Maybe this slot is for adjusting the placement for reverse direction. It's still on the bench so maybe I'll loosen the bolt and play with it a little.
 
Interesting stuff, Did some more reading and your right Ted some don't short the commutator. They're a repulsion inductive motor, the repulsion windings stay energized but produce very little torque at synchronous speed, there is a second winding on the armature that makes it a squirrel cage motor producing the majority of the torque at speed.
The repulsive start / induction run that Im more familiar with short the only winding on the rotor.
As far as reversing a repulsive start motor I understand its done by moving the brushes around the commutator.

Greg

My ARS motor reverses as you describe. The ring that the four brush holders mounts to has index marks on it and to reverse direction you loosen a locking screw and rotate the ring to the other index mark.

Ted
 
The Scot motor looks like it could be reversed if you did a little detective work on the windings- does it have a capacitor?
Anyhow it looks like you have several options there
Mark S.
 
I have a 2 maybe 3 hp repulsive start motor on my shaper, (no tags so Im guessing) the brushes on it can be moved to reverse it.
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I was given a smaller one, will have to look closer now maybe its repulsive/induction. I think it was on a gas pump, it has a sealed switch on the end with a lever to turn it on. I wanted to use it on an old Delta Milwaukee metal cutting bandsaw I restored but it turns the wrong way and the brush mounts are cast into the end cap so I couldn't get it to reverse.

Greg
 
Here's some pictures.

Isn't one of those four carbon brushes rather... short?
Could it be that there is just a bad contact from the worn-down brush? Or, maybe it's stuck
(the spring doesn't make it slide freely, maybe grit in the sleeve).

A modern motor, though, would be a bit more efficient than that old 'un. I'd look into used
motors before going on a search for replacement carbon brushes.
 
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