Motor Polarity

[CGLowry]

I have a Williams GP-9 that I going to convert to TMCC using an Electric Railroad Cruise Commander.  Does anyone know the motor polarity (blue wire positive or negative) of the motors so I don't have to use the trial and error method?

[Joe Satnik]

Dear CGLowry,

Can't tell you right off hand, but the "dot" on the motor is its direction indicator.

(In the direction of its coupler, or away from its coupler.)

Note that 2 motor locos have their front and back motor dots wired the opposite of each other. 

If they didn't, they'd fight each other, since they are pointed in opposite directions. 

Unplug a motor connector from the reverser board, lay the chassis on its side, and feed power from a D, C, or AA battery to the unplugged motor. 

Observe which way the wheels turn.   

Top of wheel (nearest chassis) moving towards coupler is moving the truck in the direction of its coupler. 

Hope this helps. 

Sincerely,

Joe Satnik 

[CGLowry]

Thank you for responding.  I've haven't had an opportunity to try your suggestion, but using batteries to check the rotation of the motors is a great suggestion.  I'll let you know the outcome.