Brake shoe residue, sand and lubricants are often introduced by operating or maintenance processes.

在车辆运行或维护过程中也会带来闸瓦的残渣，沙砾或者润滑油脂。

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The first couple-dozen laps saw brake points blown and sand traps dredged as years of potentiometer dependency was weaned away.

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After dismantling its brake drums, carburetor, motor head and oil pan to sand off the rust, he gave the refurbished car to his mother in exchange for lifts on his newspaper route.

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