Electric Motor Reversal DPDT Switch

[Dollar Bill]

I have an old Craftsman 1/4 HP split phase induction motor (113-12100) that I float between several belt driven buffer/grinders and would like to change the rotation by using a DPDT switch with center off. As the motor is portable, the DPDT is more desirable than the much larger drum switch. The motor has a yellow wire and blue wire and a terminal board with poles labeled 1 and 4. The blue and yellow leads can be swapped between poles to change rotation. Is what I'm proposing even plausible and if so, a simple wiring sketch would be greatly appreciated? Thank you for any help you can provide.


Terminal Box and DPDT Switch (Terminals Are Not Marked)

 

[FrankLee]

I have an old Craftsman 1/4 HP split phase induction motor (112-12100) that I float between several belt driven buffer/grinders and would like to change the rotation by using a DPDT switch with center off. As the motor is portable, the DPDT is more desirable than the much larger drum switch. The motor has a yellow wire and blue wire and a terminal board with poles labeled 1 and 4. The blue and yellow leads can be swapped between poles to change rotation. Is what I'm proposing even plausible and if so, a simple wiring sketch would be greatly appreciated? Thank you for any help you can provide.

Terminal Box and DPDT Switch (Terminals Are Not Marked)

What is the model number on the motor?

This drum switch wiring diagram may help.

http://vintagemachinery.org/pubs/222/576.pdf

 

[lilredex]

Think this is what you are looking for......

 

[Dollar Bill]

Think this is what you are looking for......

Thanks man! That looks right but wanted to check before I started wiring it up. I'm comfortable wiring up DC motors but AC motors are very confusing to me due to all the different designs - Induction, split phase, single phase, capacitor start, permanent split capacitor, syncronous, universal etc....

I came across one post with a similar scenario as mine and there one responder indicated with a DPDT switch the motor would not really be isolated from the line with the switch in the center (off) position - What is your take on the matter?

 

[cgrutt]

I know that wiring would work with DC, by reversing polarity. Not sure about AC though.

 

[lilredex]

Center off is just that, not connected to anything.

 

[Dollar Bill]

What is the model number on the motor?

This drum switch wiring diagram may help.

http://vintagemachinery.org/pubs/222/576.pdf

What is the model number on the motor?

This drum switch wiring diagram may help.

http://vintagemachinery.org/pubs/222/576.pdf

Craftsman stock number 113-12100

 

[Dollar Bill]

Center off is just that, not connected to anything.

That's what my little pea brain came up with but since I'd read several references saying it wouldn't made me doubt myself. Thanks again!

 

[FrankLee]

Craftsman stock number 112-12100

Oh, 113.12100

 

[Dollar Bill]

Oh, 113.12100

Ooops - Sorry I got fat fingers I fixed it.

 

[micromind]

With an AC motor, the center position of that switch is completely useless. It will change the polarity of the start winding which will indeed make it turn the other way but only after it has stopped (or very nearly stopped). Once it is running, the start winding is disengaged and the switch will have no effect on anything.

You'll need another switch to turn it on and off.

 

[gizardlizard]

You should be using a motor rated switch. Just because your load is rated for less than that switch, doesn’t mean you’re good to go. Look up motor rated switches.

 

[lilredex]

With an AC motor, the center position of that switch is completely useless. It will change the polarity of the start winding which will indeed make it turn the other way but only after it has stopped (or very nearly stopped). Once it is running, the start winding is disengaged and the switch will have no effect on anything.

You'll need another switch to turn it on and off.

You do that with that switch in the center, you only need to wait for the motor to come to a complete stop, as you have stated. Adding an additional switch offers nothing as far as the reversing action goes. My WW lathe has been set up this way for more than twenty years, with a 15 Amp. switch. The green/red switch is the main shut off and the toggle on the right governs the direction. The switch on the left is just a filler, as I remember.

 

[micromind]

The switch shown controls only the start winding, the run winding (actually, both start and run) will need to be controlled by a separate switch.

In your case, the red/green is the separate switch.

 

[csp]

With an AC motor, the center position of that switch is completely useless. It will change the polarity of the start winding which will indeed make it turn the other way but only after it has stopped (or very nearly stopped). Once it is running, the start winding is disengaged and the switch will have no effect on anything.

You'll need another switch to turn it on and off.

^^^This^^^

I had the same type of setup on an Atlas lathe. One switch was on/off and the other was the direction of rotation.

 

[Dollar Bill]

With an AC motor, the center position of that switch is completely useless. It will change the polarity of the start winding which will indeed make it turn the other way but only after it has stopped (or very nearly stopped). Once it is running, the start winding is disengaged and the switch will have no effect on anything.

You'll need another switch to turn it on and off.

Before you reply remember I'm old and feeble minded. Not fully understanding the need for a separate on/off switch. With no switches in the circuit, the hot and neutral conductors of a power cord are connected to the terminals marked 1 & 4 in the above photo. The motor is turned off by unplugging the power cord. Using Lilredex's switch wiring diagram, would not power be applied in the same manner as manually swapping the blue and yellow leads and be completely disconnected when the switch is opened in the center position?

 

[hobie18]

Used to understand electric motors.

The more I read, the less I know.

 

[micromind]

Before you reply remember I'm old and feeble minded. Not fully understanding the need for a separate on/off switch. With no switches in the circuit, the hot and neutral conductors of a power cord are connected to the terminals marked 1 & 4 in the above photo. The motor is turned off by unplugging the power cord. Using Lilredex's switch wiring diagram, would not power be applied in the same manner as manually swapping the blue and yellow leads and be completely disconnected when the switch is opened in the center position?

In your case, the cord and plug is the second switch.

If the motor is energized while the switch is in the center 'off' position, it won't start because the start winding is not energized.

The switch does not control the run winding, only the start. Both windings need to be controlled by a separate switch or in your case, by the cord and plug.

 

[Dollar Bill]

In your case, the cord and plug is the second switch.

If the motor is energized while the switch is in the center 'off' position, it won't start because the start winding is not energized.

The switch does not control the run winding, only the start. Both windings need to be controlled by a separate switch or in your case, by the cord and plug.

My intent/question is to use a single DPDT switch to both power the motor and select directional rotation. If I understand your point in this configuration, once started, the only way to turn it off is to unplug it?

 

[micromind]

My intent/question is to use a single DPDT switch to both power the motor and select directional rotation. If I understand your point in this configuration, once started, the only way to turn it off is to unplug it?

Yes, either unplug it or install a second switch to turn the entire motor on and off (same as unplugging it).