Patent ID: 7191849

Claim:
A pneumatic tool comprising: a shell comprising a chamber defined therein, a first passage communicated with the chamber and a second passage communicated with the chamber, with the second passage including an exit; a rotor installed in the chamber for rotation when driven by pressurized air flowing into the chamber through the first passage; a shaft extending to the exterior of the shell from the rotor; a trigger installed on the shell; a control device in the first passage and connected with the trigger for controlling the first passage; a muffler in the second passage; a cover extending over the exit of the second passage; and a restraint in the second passage so that the muffler is restrained between the restraint and the cover, with the second passage between the restraint and the exit being of constant cross-sectional size, with the muffler comprising a plurality of layers between the cover and the restraint, with each of the plurality of layers between the cover and the restraint consisting of an equal number of a plurality of balls.