DPDT switch to reverse rotation motor 120vac, has brushes and field coil

Thread Starter

sdowney717

Joined Jul 18, 2012
648
What I understand is need to flip the brush or field coil wires?
Was thinking an on-off-on type DPDT switch to do that.
I want to make it turn one way with switch, then reverse rotation with switch.
Motor draws a couple of amps. It is like a universal motor.
Any thoughts?
 

AlbertHall

Joined Jun 4, 2014
8,523
Electrically, a DPDT switch on either stator or rotor will do the job.
However, if the motor is running and you flip that switch, suddenly reversing the motor, bad things may happen. If you are sure to always switch the motor off and wait until it has stopped before switching on in the reverse direction that would work.
 

Thread Starter

sdowney717

Joined Jul 18, 2012
648
Pic of the basic layout.
20180716_153618.jpg It has a rubber impeller, so it shuts down real fast when turning off.
Anyone have a switch schematic I can look at?

My plan is to use it to pump oil from engines, and I was thinking, if it reversed, it could fill engines too.
I have a 4 valve manifold I created. Ths will suck from 4 different sources. The ends of the hoses will attach to engine drain plugs. Plus a couple free hoses for the trans and the generator.
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
19,182
Are you sure it is a Universal motor?
I have a drawing but I'm not at the right computer at the moment, if no-one posts it I can send it later.
Max.
 

ian field

Joined Oct 27, 2012
6,539
Electrically, a DPDT switch on either stator or rotor will do the job.
However, if the motor is running and you flip that switch, suddenly reversing the motor, bad things may happen. If you are sure to always switch the motor off and wait until it has stopped before switching on in the reverse direction that would work.
You can get a centre open changeover switch - it doesn't make wrecking the motor impossible, but the indent encourages the operator to pause.

PS: more of an issue with slide and rotary switches - but make sure its a break before make type.
 

MaxHeadRoom

Joined Jul 18, 2013
19,182
The DPDT ones I indicated can be had from any KB controller supplier, they are fitted to all of their motor reverser/control units.
They even have contacts for the dynamic braking resistor for DC motors.
Max.
 

ian field

Joined Oct 27, 2012
6,539
The DPDT ones I indicated can be had from any KB controller supplier, they are fitted to all of their motor reverser/control units.
They even have contacts for the dynamic braking resistor for DC motors.
Max.
Not sure if it helps - but a winch motor button pad someone took apart and needed me to figure out, had 2 independent poles. It was impossible to engage both directions at once. You might need more than 2 poles without DC.
 

Thread Starter

sdowney717

Joined Jul 18, 2012
648
Here is the diag, excuse the armature symbol for the field.
Max.
Thank you for that.
My idea is use an on-off-on switch with no separate on-off switch.
I assume it is like a universal motor, there are no permanent magnets.
How does an electric drill reverse switch work, same idea?

Found a pic for DC , AC be the same.

 
Last edited:

ebp

Joined Feb 8, 2018
2,332
http://www.newark.com/eaton/7992k10/switch-toggle-dpdt-15a-250v/dp/11M1832

This is an example of a toggle switch intended specifically for motor reversal. The manufacturer, Eaton, calls it a "hesitation switch." They are centre off and in order to go from one ON position to the other, you have to release the force on the toggle handle in the centre position before you can move it to further. For a system with a lot of inertia that kept the motor spinning for a long time after removal of power it wouldn't help a lot, but if the motor stops quite quickly it is effective. Not what you'd call cheap, but not hideously expensive.
 
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