| 摘要 |
1,075,520. Percussion drills. GARDNERDENVER CO. Dec. 15, 1964 [Jan. 16, 1964], No. 50932/64. Heading B4C. [Also in Division F1] In a pneumatic tool having a silencer 27 mounted on a casing 13 and communicating with exhaust port 12, the silencer has an unobstructed main passage having peripheral openings which define auxiliary flow paths from the main flow path. Exhaust air flows via port 12, passages 11 and chamber 20 and through three main flow passages in partition 18 to silencer 27 which consists of spaced nylon plates 27. Auxiliary flow paths are formed by the spaces between plates and air flows therethrough into smaller passages between the main passages. The emerging air impinges on deflector 36 and passes to atmosphere through notches 24 in the sidewall of the casing. Silencing is also provided by a resonance chamber 19 and a porous material 36, e.g. felt. In another embodiment the exhaust port emerges directly into a resonance chamber from which separate openings lead to the silencer.
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