Need help with electric motor

[TractorTucker]

I bought an old drill press last week and it has a 3/4 horse electric motor on it. The motor hums but it will not run. I tried spinning it while it was on to see if it would start and it still would not. I pulled the motor apart but I don't know enough about electric motors to even start troubleshooting it. Any thoughts on what I can do to try and fix it?

 

[Janicholson]

Look at the ID plate. (it might be inside the electrical cover plate.) if it is 3 phase it will not run on single phase no matter what. If single phase it might have starting circuit (capacitor/s and/or governor for starting contacts) We can sure help it to spin if we have more details, like a photo of the plate. Jim

 

[TractorTucker]

 

[OldFarmTractor]

It can be wired 220 or 110. Make sure it is wired in correctly.

 

[Steve@Advance]

Wow! That is an oldie!

I saw one like that years ago. Never really studied the theory on it, but was designed for instant reverse and jogging without using a capacitor or centrifugal switch.

The brushes were part of the starting circuit.

I got it working cleaning everything up, had mud dobbers in it.

 

[TractormanNC]

That is an OLD OLD motor called repulsion start induction run. Designed for high starting torque with low starting current for use in rural areas where the power was weak out away from cities and power substations. Best thing you can do is throw it in the scrap pile and go buy a modern capacitor start motor. There were four of those on the farm when I took it over, none now.

 

[Janicholson]

If the laminations in the field (inside of the cylinder) were polished shiny and clean, and the brushes and commutator bars were clean and the bars polished and recleaned, and the brushes were long enough to have fair pressure on the segments, it will probably run. It is certainly interesting as Steve points out. If it doesn't, or appears to be the reason the press was out of service, replace it with a three phase motor and a VFD converter to make the drill press operate. Jim

 

[TractorTucker]

How do the brushes work? There doesn't seem to be a spring or anything that keeps them pressed to the armature.

 

[buickanddeere]

You may have the polarity of the field windings subtractive instead of additive .
Swap the polarity
Of one of the 120V windings .

 

[Stephen Newell]

The problem I have when I take a motor apart is something happens and it's months before I have time to work on it again. By then it's like someone else took it apart. Don't know how it goes back together.

 

[Hdonly]

(quoted from post at 06:43:23 08/15/21) If the laminations in the field (inside of the cylinder) were polished shiny and clean, and the brushes and commutator bars were clean and the bars polished and recleaned, and the brushes were long enough to have fair pressure on the segments, it will probably run. It is certainly interesting as Steve points out. If it doesn't, or appears to be the reason the press was out of service, replace it with a three phase motor and a VFD converter to make the drill press operate. Jim

Tats what I did with my drill press. Total speed control. Forward/reverse. Best thing I ever did.
https://youtu.be/amWPpApY2nM

 

[JMOR]

(quoted from post at 19:37:52 08/15/21)

(quoted from post at 06:43:23 08/15/21) If the laminations in the field (inside of the cylinder) were polished shiny and clean, and the brushes and commutator bars were clean and the bars polished and recleaned, and the brushes were long enough to have fair pressure on the segments, it will probably run. It is certainly interesting as Steve points out. If it doesn't, or appears to be the reason the press was out of service, replace it with a three phase motor and a VFD converter to make the drill press operate. Jim

Tats what I did with my drill press. Total speed control. Forward/reverse. Best thing I ever did.
https://youtu.be/amWPpApY2nM

ther than old, there is nothing wrong with repulsion start/induction run.. I have one on 1927 air compressor & replaced brushes around 1960 and it still pumps air today.

 

[Super H Mike]

When my old repulsion motor did that it was because the brushes were worn enough that there wasn't enough pressure pushing them into the commutator. My local electric shop had some similar ones and I filed them to fit.

 

[JMOR]

(quoted from post at 10:24:01 08/16/21) When my old repulsion motor did that it was because the brushes were worn enough that there wasn't enough pressure pushing them into the commutator. My local electric shop had some similar ones and I filed them to fit.

id same thing & before I got around to it, I stuck a stick in to push brush holder against commutator until up to speed. My Dad showed me & brother how to use the stick. When old enough, I installed the new brushes.

 

[Janicholson]

The brush frame is controlled By a spring loaded linkage that is driven by a start governor. Below a certain rpm, as the turned off motor slows down from running, the governor toggles the brush frame into the commutator. The next time the motor is powered up the brushes drive starting AC into the start windings applying solid starting torque to the armature. When the governor reaches its trip RPM, the brushes are pulled away (rapidly) and a shorting ring connects the commutator bars making a induction rotor out of a repulsion rotor, allowing the electricity to run normally from there on up. Jim
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