DC Motor question

[JRLesan]

Motor is a small automotive blower motor for the heater/defroster. I need to reverse it. It appears to be a series wound circuit but unlike ones I've encountered before. Positive (or negative) voltage in the field winding and out the other end to a brush. Both field windings wired the same instead of being connected end to end and then to a brush with the opposite brush being the return leg. I'm unsure how to proceed...

[deltaenterprizes]

Reverse polarity of the supply voltage!

[Recycled bullet]

If the fan uses two wires just switch the polarity. Also check if it's got the angled fan blades to push air around it might not function too well in reverse especially if it's not getting installed into a ducted cage and spinning a different direction than it is designed.

[JRLesan]

Well, there's TWO wrong answers.

[1006]

I think you would have to go in the motor and reverse either the field or the armature, but not both.

I say this because of an experience I had with a British sports car in which the battery had been installed backwards. Oddly enough, the engine still started with the starter, and I believe the windshield wipers still functioned. The radio did not function until I turn the battery around and then everything functioned.

As to how to accomplish your task: I don’t know.

[super6]

Reverse polarity of the supply voltage!

Well there you go!

[kerplode]

I think you would have to go in the motor and reverse either the field or the armature, but not both.


This is the correct answer...


As to how to accomplish your task: I don’t know.
Agreed. It can be a bit of surgery...

[deltaenterprizes]

Well, there's TWO wrong answers.

Please tell us the answer!
I started with DC electrical motors in around 1963 when I was given an Erector Set that included a DC motor with a clear plastic housings and found out that switching polarity changed the direction of rotation!
In 5th grade a couple years later I started doing DC electrical experiments for science projects.
In 7th grade in electrical shop we built an electrical motor for a project.
After high school I took a semester in Electrical construction and worked doing electrical work building electrical panels.
I then went to school for Electronic Technology and worked as an electrician until 2005.
I still do electrical repairs when needed.
I happen to have a spare blower motor from a 2012 Chevrolet Trailblazer.
I connected it to a battery charger and then reversed polarity and rotation reversed!

[rancher1913]

dont you just love when somebody asks for help then tells the people trying to help you they are wrong.

[Recycled bullet]

Well, there's TWO wrong answers.Did you install the battery backwards hahaha!

[JRLesan]

Series wound is the operative; reversing polarity will NOT reverse rotation. If I knew EXACTLY how to reverse field polarity in relation to armature polarity I would not have asked. BUT, thanks for the few 'smarty pants' responses and 1006's answer which is correct but does not explain exactly how.

[alfadan]

Sheesh

[uscra112]

Can you access the commutator and brushes? I would think you could pick the wire from the field to the brushes off the first brush, put it on the other brush, and carry the wire coming out the first brush. Thus reversing the armature. I think. Not an electrical engineer, me. Just an old dirty-fingernail mechanical type.

What this would do to the brush timing I wouldn't know.

[deltaenterprizes]

Series wound is the operative; reversing polarity will NOT reverse rotation. If I knew EXACTLY how to reverse field polarity in relation to armature polarity I would not have asked. BUT, thanks for the few 'smarty pants' responses and 1006's answer which is correct but does not explain exactly how.mm

So what you have is a universal motor not a typical DC motor?

[JonB_in_Glencoe]

you need to change the polarity on the Armature.

https://qph.cf2.quoracdn.net/main-qimg-5bfcd886dd231586370958f9b0b74bd8-lq

[JRLesan]

I'm not sure what I have. The field windings, of which there are two, are wired in series with one brush each but are NOT wired in series with one another. Voltage input is to each field. The fields are wound in opposite directions which is what one would expect. My experience, which is admittedly limited, is with BOTH field windings in series with one another and then to ONE brush with input to one winding and one brush. I suspect, but do not know, that switching the brush leads between the two field windings would reverse direction but disassembling the little motor was tedious and I'd prefer not to have to do that a second time...

[JRLesan]

Thank you, Delta. I do have a universal motor and a little research confirms how to reverse it.

[deltaenterprizes]

Thank you, Delta. I do have a universal motor and a little research confirms how to reverse it.

Glad to help!