In article ,
Daniel Rudy wrote:

Cross Post: sci.electronics.repair, comp.robotics.misc

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Hello Groups,

I have recently acquired two heavy duty motors for robotics use. Below
is a link to the picture of one of them.

http://www.mpja.com/prodinfo.asp?number=14386+MD

I have both a left hand and a right hand motor. They are about a foot
long, half a foot wide, and weigh in at about 40 lbs each (No wonder it
cost $40 for shipping...UPS ground even.). The motor also has
serviceable brushes too. There are four wires for these motors, colors
red, black, white, and yellow. I'm going to assume that red and black
are power, but what are the white and yellow for? A built in
tachometer? The gearing is bolted on, but there doesn't appear to be
any way to dismantle the motor so I can see how it is wired internally.
Any thoughts or suggestions?

Two of the wires for the armature, two for the field.