OT---electric motor

Jiles · Nov 1, 2012

I have a small 110v ---1 hp motor on a radial drill press. The motor is nearly new but when I started to use it, after setting for a long time, it would not start. I removed the belt and it still has trouble starting. There is no start capacitor. There is a centrificul devise that you can hear when the motor is shutting down. That seems to be working.
Strange thing is---sometimes it will start and run in either direction???

buickanddeere · Nov 1, 2012

If there is very little starting torque and the motor will radomly
start in either direction. That means there is zero current
flowing in the start winding.
Time to drag out the ohm meter and check continuity.

Anonymous-0 · Nov 1, 2012

Sawdust has probably got into the starter switch. Blow it out thoroughly with an air compressor.

Paul from MI · Nov 1, 2012

Most likely the centrifugal switch in the motor is not closing when the motor slows to a stop, or the "start" winding is open. Therefore the "start" winding is not energized when you turn the motor back on, and only the "run" winding is energized. So the motor may start and run in either direction or not start at all until you manually spin it. As B&D says, check the centrifugal switch with an ohmmeter. If it's OK, then your next stop is the motor shop.

John T · Nov 2, 2012

That single phase split phase (sounds like what you have) motor doesnt require a capacitor in the start winding to start, its just that a capacitor start split phase motor has improved start up torque versus one that doesnt. Since those motors are NOT self starting (would sit n hum n buzz if no start circuit is activated and dont know "which way to turn" lol), they require a seperate start winding that basically gets them spinning IN A PARTICULAR DIRECTION and then is taken out of the circuit when a centrifugal activated switch opens at X RPM. If that switch is defective or has resistive carboned up contacts it may cause the motor to not start and/or not start as well. If you can ohm out the switch it should have near zero resistance when closed but if its burned and carboned resistance greatly increases THE SWITCH IS LIKELY THE PROBLEM IT SOUNDS LIKE

John T

showcrop · Nov 2, 2012

As others have said it sounds like the start winding switch. We used to take motors with failed switches to the local motor repair shop where they would install a "SYNPAC". solid state start winding switch. These motors were on commercial dish washing machines and had to start hundreds of times a day, and break downs were a big problem.

Walt Davies · Nov 2, 2012

Years ago I worked at a very old small army base on the river
in CA. We had an air compressure from the 20 it was run by
this huge motor, about 4 ft high not sure of the horse power
but it was a lot as it had to run a huge air compressure. To
start it you took ahold of this very long lever and pushed it to
the back then throw the switch wait for motor to start turning
slowly then move lever forward. If all goes well an it doesn't
blow the main buss fuse it will slowly come up to speed.
Aren't these old machines wonderful.
Walt

OT---electric motor

Jiles

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buickanddeere

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Anonymous-0

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Paul from MI

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John T

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showcrop

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Walt Davies

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