US Patent 7238095 Pneumatic grinder with improved muffling structure

A pneumatic grinder with improved muffling structure primarily comprises a driving portion, a grinding wheel fixing portion provided at one end of the driving portion, a first housing connected to the other end of the driving portion by means of a combining portion, a second housing mounted onto the first housing, and a plurality of first and second exhaust openings arranged in staggered fashion respectively on the first and second housings. Said structure allows the pneumatic grinder to discharge waste air through foresaid two layers of exhaust openings in staggered fashion arranged in order to reduce noise during air exhaust.