| 摘要 |
A drill bit assembly has a housing having a central passageway including a pressure chamber and a vacuum chamber. The pressure chamber is connectable with a pressure source and the vacuum chamber is connectable with a vacuum source. The pressure chamber and vacuum chamber are in fluid communication with each other. A bearing assembly has an outer race rigidly mounted within the pressure chamber and an inner race for frictionally engaging the drill bit. A bracket mounts the housing with the drill bit extending through the central passageway. A seal is formed between the pressure chamber and the vacuum chamber as fluid, such as air, from the pressure source flows into the pressure chamber to the vacuum chamber for exhausting to the vacuum source.
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