1, from an intuitive point of view, the brush should chamfer decent, appropriate specifications, structural specifications, cross-section and length of the wire required, no loose, loss, damage, off side, off angle, clamp and other phenomena.

2, from the use of point of view, the good sign of brush to use mainly the following situations:

(1) long service life, and do not wear commutator or collector ring, not the commutator appeared scratches, uneven, ablation, drawing.

(2) has a good commutation and the current collecting performance, and the spark suppressed within the allowable range, and the energy loss is small.

(3) brushes run, but the heat, the noise, not broken, do not change color brush braid, no ablation.

(4) during operation, it is possible in the commutator or collector ring surface rapidly to form a uniform layer, moderate and stable oxide film.

3, the pair of brushes carried by the instrument detection. From a technical perspective, the brush shall conform to the national ministerial standards. The pair of brushes in accordance with the performance required by the "brushes technical performance table detected by the instrument. Such as the resistivity of the brush, Rockwell hardness, and a bulk density, and current density, the contact voltage drop, friction coefficient, wear 50 hours, to allow a circumferential speed, the unit pressure, even as the size of the metal content, and so on. Now my only muddled here. I do not know how these parameters are measured. The experts give pointers. And whether these parameters for the measurement data of general motors for power tools motor brush and how measured it?

4, on the same motor, should choose to use the same model, same manufacturer of brushes. The brush performance differences of different manufacturers, and even the brush performance produced by the same manufacturer at different times are also different. Thus, with regard to the same motor, you should try to choose the same model the same factory, production of brush is best at the same time, in order to prevent parallel brush current distribution imbalance due to differences in the brush performance, affecting normal motor operation.

5, for the individual choice of sub-braid brush commutation particularly difficult for large and medium-sized motor. The purpose is to increase the short-circuit current within the brush to improve the performance of commutation. Difficult motor for unidirectional rotation change to the option of using a combination of brush. That choose to use a good lubricating properties, film-forming ability, low resistance value graphite-based electrochemical graphite brush onto the side, slide out side choose to use the change to the good performance of high resistivity carbon black-based electrochemical graphite brushes. In this way, easy to form the oxide film, and play a great role in the improvement of commutation performance. Slide out side carbon fiber composite brushes can be used to highlight the use of the its interrupter ability characteristics, so that the motor‘s running to get the best results.