| 摘要 |
PROBLEM TO BE SOLVED: To provide a brush which enables improvement of its sliding performance. SOLUTION: Four corners 51-54 of a brush 10 are made to protrude the most toward a commutator 3. Two diagonals from the corners 51 and 52 of the brush 10 to two diagonal corners 53 and 54 are formed on the sliding surface 20 of the brush 10 as two ridge lines 61 and 62. In other words, two inclined surfaces 34 and 35 and pairs of inclined surfaces 23 and 24, of which the sliding surface 20 of the brush 10 is composed, are inclined relative to the commutator 3. As a result, in the initial stage, the four corners 51-54 are made to slide on segments 12, and following the wear of the brush 10, the areas of the parts of the sliding surface 20 of the brush 10 which are made to slide on the segments 12 are gradually enlarged along the two ridge lines 61 and 62. That is, following the wear of the brush 10, the whole sliding surface 20 is gradually made to slide on the segments 12. The sliding performance of the brush 10, therefore, is improved.
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