File talk:Carbon brushes.jpg

I am Product Manager in order to the carbon brushes and I can observe in the picture that the carbon brushes has been used before.

Also, I can observe several grooves over the surface of contact of the brush with the collector. It means that the grade of carbon is not the optimal for this motor. In this case the carbon brush has not had a good performance.

The grade of the carbon is the principle factor of the performance. There are several grades of carbon with the object to manufacture carbon brushes and further that fit to different needs of the existing motors: design, speed of the motor, voltage, power and vibrations of the machine...

Then, when a carbon brush has a good performance, the surface of contact looks gleaming and the effect seems as the mirror surface. This texture and appearance is known as 'patina'.

If you need more information, please let me know via e-mail:

escombretes@yahoo.es