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A muffler for use with machines such as pneumatic drills consists of an elastomeric housing divided into an admission chamber and a series of muffler chambers. Within the housing are an inlet conduit communicating with the admission chamber and each muffler chamber, an exhaust conduit communicating

A muffler for use with machines such as pneumatic drills consists of an elastomeric housing divided into an admission chamber and a series of muffler chambers. Within the housing are an inlet conduit communicating with the admission chamber and each muffler chamber, an exhaust conduit communicating with each muffler chamber as well as with a tail pipe outside the housing, and a Helmholtz resonator communicating with the admission chamber.

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A muffler for a pneumatic impact device operating at a frequency below about 60 Hertz comprising a housing adapted to receive and discharge exhaust gas from said impact device and made of an elastic, high damping, hydrophobic material, a gas entrance chamber in said housing communicating with a Helm

A muffler for a pneumatic impact device operating at a frequency below about 60 Hertz comprising a housing adapted to receive and discharge exhaust gas from said impact device and made of an elastic, high damping, hydrophobic material, a gas entrance chamber in said housing communicating with a Helmholtz resonator tuned to a frequency in the range of about 500 to 2,500 Hertz, a gas transport conduit exiting from said gas entrance chamber at an abrupt angle from the direction of gas entrance into said chamber, a plurality of first ports in the walls of said gas transport conduit, said first ports having a total cross-sectional area at least equal to the cross-sectional area of said gas transport conduit, a gas discharge conduit closed at its inner end and having a plurality of second ports in the walls thereof, a plurality of mutually isolated gas transport chambers each in communication with at least one of said first ports and at least one of said second ports, each of said gas transport chambers having a cross-sectional area substantially greater than the cross-sectional area of said first and second ports in communication therewith, the gas path in said transport chamber being at an abrupt angle from both the direction of flow in said gas transport conduit and in said gas discharge conduit.