| 摘要 |
A brush wear indicator for a dynamoelectric machine including a brush holder for slidably mounting a brush, a self-winding, brush-biasing spring having one of its ends mounted in fixed relationship on the brush holder, in combination with a circuit board having a dielectric member on which a plurality of electrical contacts are mounted in spaced relationship to be electrically engaged by the spring when it is fully extended to accept a new brush in the brush holder. As the brush wears, the spring moves downward to continue exerting a biasing force on the brush, and sequentially moves out of engagement with the contacts on the circuit board responsive to predetermined degrees of brush wear occurring. Such movement of the spring causes the contacts to be sequentially disengaged from the spring, thereby causing associated signal means, such as glow lamps, to be de-energized thus indicating the occurrence of the predetermined degrees of brush wear.
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