Patent ID: 7303363

Claim:
A drill, comprising: a tubular outer housing having a longitudinal axis; a tubular inner housing mounted in the outer housing for reciprocal axial movement relative to the outer housing along the axis between retracted and extended positions; an annular feed chamber between an outer diameter portion of the inner housing and an inner diameter portion of the outer housings; a pneumatic motor assembly having a chuck adapted to receive a drill bit for rotation therewith, the motor assembly being carried in the inner housing for axial movement therewith; an annular feed piston mounted on the outer diameter portion of the inner housing for movement therewith and located in the annular feed chamber in sliding reciprocal engagement with the inner diameter portion of the outer housing; a feed passage for supplying air pressure to the feed chamber on one side of the feed piston to move the inner housing from the retracted to the extended position; and a sealed annular fluid restrictor chamber located between the outer diameter portion of the inner housing and the inner diameter portion of the outer housing and containing a hydraulic fluid, the restrictor chamber having an orifice through which the hydraulic fluid flows in response to the movement of the feed piston toward the extended position for controlling a rate of movement of the inner housing relative to the outer housing from the retracted to the extended position.