# Small 12v motor advice please



## Woodsmith (Jun 5, 2008)

I have a small motor that I want to use for a little 12v EV kart project for my Dad.

It came off an old electric bicycle, I believe, and is branded as a SIBA 2 Speed Motor.

















The label reads:
Type TM: 4132 Rotation: ----->
Series: 1774 Voltage 12v

It has two bolt terminals and a flying lead.

I opened it up and mapped the wiring inside and it is like this:








Terminal A is insulated from the frame.
Terminal B is grounded to the frame.
Terminal C is a flying lead.

The brushes are at 90deg to each other.

If I connect a battery to A and B the motor spins very fast. If I then connect C to B the motor runs very much slower.

Is this right?

How might I reverse the direction as it currently spins the wrong way? The brush box that is connected to B is also grounded to the CE cap on the mounting rivets whereas the other brush box is insulated.

I want to use it to drive a mower axle that has a reverse gear but at much lower ratio then forwards so I don't want to drive it the wrong way if possible.









Thank you.


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## major (Apr 4, 2008)

Hi wood,



Woodsmith said:


> If I connect a battery to A and B the motor spins very fast. If I then connect C to B the motor runs very much slower.
> 
> Is this right?


I think so 


> How might I reverse the direction as it currently spins the wrong way?


Somehow relocate the brushes or the field 90º from their present location. Twist the CEH (bracket with brush holders attached to it) if possible. If that isn't easy due to the build, you could move the field coils over to adjacent poles shifting them 90º.

Another method would be to reverse the current flow thru the field coils by switching the wires coming from the coils. Take the blue wire from the coil at 9 o'clock going to the brush and move it to terminal A. Replace it to the brush with the blue wire originally on A. And reverse the red wires going to A and C.

Follow that 

major


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## Woodsmith (Jun 5, 2008)

That's great, thank you major. I will try swapping the field coil connections as it is easier then turning the CE.

I might save on the controller by having a three position switch, off, slow and fast, as a throttle. I figure the motor is only a few hundred watts at best and Dad will be safe with that to play with.


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