| 摘要 |
<p>A multi-speed, direct current motor (120) incorporates a high speed (24) brush disposed between the low speed (22) and the common ground (26) brushes and having a non-arcuate end face (25) which , unlike the conventional arcuate brush end face (23, 27), is not subject to speed-drift erosion. The non-arcuate end face (25) is configured of two offset surfaces (55, 65 and 57, 67) which intersect to provide a line of contact (43) between the end face (25) of the high speed brush (24) and the commutator (40) which is displaced from the center line of the high speed brush (24) in a direction counter to the direction of rotation of the motor, that is toward the leading edge (21) of the brush (24). The intersecting surfaces (55, 65 and 57, 67) may comprise either flat planar surfaces or contoured surfaces.</p> |
