Abstract: A filter apparatus for a percussion device to be powered by fluid pressure, which when the apparatus is in an assembled position, comprises a filter recess formed within a housing encasing the percussion device. An assembly fastener is disposed within the recess. A first filter is disposed about the assembly fastener. A filter support is disposed about the first filter. A second filter is mounted around the filter support. Both the first and the second filter have a filtering gauge size, and the filtering gauge of the first filter exceeds the filtering gauge of the second filter.

Abstract: A filter apparatus for a percussion device powered by fluid pressure includes a percussion device housing having a fluid inlet and a fluid outlet. A valve is displaced between an open and a closed position. A filter recess is formed within the housing. A filter is inserted within the filter recess for moving the valve from the closed to the open position, thereby permitting fluid pressure to be supplied from the inlet to the outlet.