Toggle switch to reverse rotation

[whitmore]

A DPDT toggle switch can change direction, but there's no guarantee the switch (or motor) will
tolerate it being disturbed when the motor power is ON. To switch power off every time the direction-change
contacts are disturbed, it's usual to use a four-section fwd-off-reverse type switch, with two
sections for LINE and N (115V) or Line1 and Line2 (230V).

Like this: four-section reverse switch

 

[gard]

A DPDT toggle switch can change direction, but there's no guarantee the switch (or motor) will
tolerate it being disturbed when the motor power is ON. To switch power off every time the direction-change
contacts are disturbed, it's usual to use a four-section fwd-off-reverse type switch, with two
sections for LINE and N (115V) or Line1 and Line2 (230V).

Like this: four-section reverse switch

That looks like the right way but I will bet it is a lot more expensive than the 4 way light switch from the local hardware store I added to a cap start drill press that rarely gets used in reverse.

 

[markba633csi]

There is a mistake in your sketch
Give me a sec
This should work: ....... be sure to provide a ground wire to the motor case- not shown

 

[wilton]

Using the pole-reversing switch assumes that another, inline, SPST on/off switch (in the positive/feed power wire) comes before the pole reverse switch to ensure the motor is not powered when it is switched from forwards to reverse and causes a momentary electrical stall and/or possible arc that can damage the windings.

At least, that is how it was explained to me by several electricians. It may just be a way to say "dont reverse polarity of a running motor, wait until it stops before switching direction" which should be common sense.

You dont shift into reverse at speed in a car (not that you could even if you tried!), so don't do it with electrical motors.

Did actually get the point when accidentally I flipped the switch from forwards to reverse on my mains power hammer drill once due to the way I was holding it. Not something I have ever repeated since!! The momentary arc from the comm and brushes as well as the jolt from the reversal whilst the armature was still spinning was warning enough never to do that again.

 

[wilton]

Using the pole-reversing switch assumes that another, inline, SPST on/off switch (in the positive/feed power wire) comes before the pole reverse switch to ensure the motor is not powered when it is switched from forwards to reverse and causes a momentary electrical stall and/or possible arc that can damage the windings.

At least, that is how it was explained to me by several electricians. It may just be a way to say "dont reverse polarity of a running motor, wait until it stops before switching direction" which should be common sense.

You dont shift into reverse at speed in a car (not that you could even if you tried!), so don't do it with electrical motors.

Did actually get the point when accidentally I flipped the switch from forwards to reverse on my mains power hammer drill once due to the way I was holding it. Not something I have ever repeated since!! The momentary arc from the comm and brushes as well as the jolt from the reversal whilst the armature was still spinning was warning enough never to do that again.

 

[wilton]

There is a mistake in your sketch
Give me a sec
This should work: ....... be sure to provide a ground wire to the motor case- not shown
View attachment 499378

Thanks Mark. That is very clear. Even I should be able to follow it. It does answer a major question I had. I will do a bench wiring now to try it. I was using the white/Neutral in the external switch for on-off but will change that to the black/hot. Once I get it working on the bench I will install it at the house. I do have a ground wire as well. I am using a metal handy box to house the reversing switch between the on/off switch and the motor. Should the ground be connected to it as well? Thanks again.

 

[wilton]

Thanks Mark. That is very clear. Even I should be able to follow it. It does answer a major question I had. I will do a bench wiring now to try it. I was using the white/Neutral in the external switch for on-off but will change that to the black/hot. Once I get it working on the bench I will install it at the house. I do have a ground wire as well. I am using a metal handy box to house the reversing switch between the on/off switch and the motor. Should the ground be connected to it as well? Thanks again.

Mark
I ran a bench test and it works great. Flip the toggle switch and the motor reverses as it should. Thanks very much.

 

[markba633csi]

Great! Yes ground the little box too.
Usually, it's preferable to open the hot lead to shut off the motor although either lead would work

 

[gard]

There is a mistake in your sketch
Give me a sec
This should work: ....... be sure to provide a ground wire to the motor case- not shown
View attachment 499378

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I am no expert but some of the cap start motors I have seen say to reverse rotation switch these two wires on those 2 connectors, no mention of connecting the wht/Neut to the DPDT switch. So in this case the wht/Neut goes straight into the motor. I have no idea if it is functionally the same as you have drawn.

 

[markba633csi]

It's functionally the same- a connection is a connection unless you are talking about very high frequencies or very long wire lengths then
it might matter where/how you connect it.

If the motor was large and drew a heavy current it might be better to run the neutral wire direct to the motor instead of detouring thru the reversing switch; I drew it that way for clarity since it's a relatively small motor, small current draw