By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale

Can this motor be reversed?

All Topics | Latest Posts

Search for:  in Thread Title in  
SteveM09/08/2018 11:38:11
62 forum posts
16 photos

Hi all,
Sorry if an identical question has already been posted and answered - if it has I cannot find it, so please point me in the right direction.

I want to use this ex floor polisher motor for my concrete mixer, an old Benford. The motor would be perfect if only it could be made to turn in the right direction.

Before I am tempted to switch some connections on the start circuit that could kill me or the motor, can anyone tell me if the direction of rotation can be changed easily - or has it been fiendishly designed to make it difficult?
The black cable is live in.

There are some more pictures in an album which may help.

motor1.jpgmotor5.jpg

Edited By SteveM on 09/08/2018 11:39:31

FMES09/08/2018 12:25:48
avatar
478 forum posts
1 photos

If its a brushed motor, just swap the two brush leads around, if an induction (no brushes) undo the motor ends and turn the armature round.

Seeing this is from a vacuum cleaner (?), it will probably be way too fast for your mixer.

Regards

Clive Foster09/08/2018 12:30:41
1461 forum posts
34 photos

Yup.

Capacitor start, capacitor run motor so all you have to do is identify the start winding and reverse its connections. Which may take some effort as, being a proprietary motor it probably doesn't have the usual handy connection and winding layout diagram on the electrical input box lid.

Quick google shows plenty of diagrams, references and a youtube or two on the subject. Best to research for advice that suits your skills and your equipment.

Take a close look at cooling airflow arrangements. Appliance motors of this sort intended for indoor duty often need a good flow of clean air through the insides to keep them happy. Clean air and concrete mixers are generally fairly incompatible concepts. Good electric mixers tend to use sealed motors.

Clive.

SteveM09/08/2018 14:01:24
62 forum posts
16 photos

Thanks for the replies, and sorry, perhaps I should have added some more information in the original post.

It's a 4-pole induction motor so circa 1450 rpm. 1000w. Single phase. Sadly there is no handy wiring diagram anywhere, but at least the wires are different colours! I'm pretty sure the start capacitor is the black 100 μF and the run is the white 10 μF.
The motor will be housed in a filtered enclosure.
It's from a floor polishing machine, and when fitted with a 2 inch pulley will rotate the drum at 24rpm.

I know it will work beautifully because my last mixer was an identical Benford. It worked just fine with a similar setup for more than a decade and I would have it still but some passing vermin took a fancy to it while I was at work.

I was really hoping that somebody would have encountered the same wiring arrangement and the solution would be as simple as 'swap the black wire with the yellow'!

Edited By SteveM on 09/08/2018 14:11:30

John Rudd09/08/2018 15:00:12
1215 forum posts
57 photos

You are half way there.....

Follow the wires from the Start cap, this will take you to the Start winding, then just swap over...

Les Jones 109/08/2018 15:12:44
1999 forum posts
135 photos

Does the brown wire from the run capacitor (10 uF) connect to the same terminal on the start capacitor (100 uF) as the yellow wire ? Is the wire connected to the left hand push on connector yellow and green and is it connected to earth ? Where does the blach wire go to that disappears below the left hand push on connector ? Where do the earth, live and neutral on the incomming power cable connect ? I suspect that you will have to open the motor to get directly at the ends of the windings to reverse the motor.

Les.

Tim Stevens09/08/2018 15:37:03
avatar
917 forum posts

If you find the change impossible, think about the option of fitting the complete motor as it is, but reversed end to end. No doubt it will then stick out in the way (etc) but a bit of ingenuity might reveal a solution.

Tim

Clive Foster09/08/2018 16:17:44
1461 forum posts
34 photos

This is the classic single phase capacitor start, capacitor run motor wiring diagram :-

start & run.jpg

When 1/4" blade terminals are used for motor wiring the wires all the wires are frequently bought out to the electrical input box with the dual blade terminals on the run capacitor used as a sort of junction box. If you can print out that diagram and annotate colours it should become clear.

Clive

John Haine09/08/2018 16:39:59
2036 forum posts
113 photos

The critical question is whether one end of both the start and run windings are commoned together inside the motor or outside. You need to swap the connections to either the start or the run winding, so you need to find the appropriate connections. If the common is inside it might still be possible to get at it; but if you can't then the motor cannot be electrically reversed.

Phil Whitley09/08/2018 19:34:11
668 forum posts
101 photos

You reverse a single phase motor by reversing the polarity if the START winding, reversing the polarity of the run winding makes no difference. reversing the polarity means simply disconnection the winding, swapping over the connections end for end, and reconnect. On the above diagram this would mean disconnecting the start winding from its connections to the incoming supply and the run capacitor and swapping them over. A single phase motor will run in eother direction, once started in that direction, which is why you have to reverse the start winding.

John Haine09/08/2018 20:18:59
2036 forum posts
113 photos

I guess you'd agree that if I just reversed the mains connections to the whole motor, it wouldn't reverse? So if I reversed the connections to the run winding and also the mains connections, it would be exactly the same as if you reversed only the connections to the start winding. So you can swap over either but not both.

The key thing for the OP is to look at the motor, not the capacitors, and check that both ends of each winding are accessible.

Emgee09/08/2018 20:46:02
872 forum posts
182 photos

Plus 1 for Phil's advice ref changing the start winding ends to reverse, older motor start windng wire colours were yellow and blue but not all followed convention.

Emgee

SteveM09/08/2018 23:05:50
62 forum posts
16 photos

Posted by John Rudd on 09/08/2018 15:00:12:

You are half way there.....

Follow the wires from the Start cap, this will take you to the Start winding, then just swap over...

Many thanks John, that was just what I needed. The job was done and the rotation reversed. Made me ridiculously happy!

Just to explain fully in case anybody else has a similar motor, this is what I found when I removed the back end.

20180809_224310.jpeg

The yellow and blue wires from the start capacitor were traced to the posts subtly red arrowed in the picture.
All I did was swap these two cables, carefully reassemble and nervously power up. Nothing went bang and the motor direction was reversed. It's running beautifully.

Many thanks to all who chipped in with advice!

Cheers,
Steve

Michael Gilligan10/08/2018 10:28:05
avatar
11738 forum posts
517 photos

Posted by SteveM on 09/08/2018 23:05:50:

... Just to explain fully in case anybody else has a similar motor, this is what I found when I removed the back end.

20180809_224310.jpeg

The yellow and blue wires from the start capacitor were traced to the posts subtly red arrowed in the picture.

All I did was swap these two cables, carefully reassemble and nervously power up. Nothing went bang and the motor direction was reversed. It's running beautifully.

.

And thanks to you, Steve ... for providing exactly the sort of 'closure' that is so often lacking yes

MichaelG.

Phil Whitley10/08/2018 16:54:20
668 forum posts
101 photos
Posted by John Haine on 09/08/2018 20:18:59:

I guess you'd agree that if I just reversed the mains connections to the whole motor, it wouldn't reverse? So if I reversed the connections to the run winding and also the mains connections, it would be exactly the same as if you reversed only the connections to the start winding. So you can swap over either but not both.

The key thing for the OP is to look at the motor, not the capacitors, and check that both ends of each winding are accessible.

No John, reversing either or both mains and start winding will make no difference. the starting capacitor creates an artificial second phase which gives a directional pulse to the start winding. only reversing the polarity of the winding reverses the direction of the initial pulse. If you connect a single phase motor without the start winding, and spin the shaft manually it will run in the direction you spin it in, regardless of the line connections or run winding polarity.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Eccentric Engineering
Ausee.com.au
Expo Tools July 14
Meridienne Sept 5
Sarik
TRANSWAVE Converters
Shapiro
Warco
ChesterUK
SPG Tools October Seventeen
Allendale Electronics
emcomachinetools
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest