Importance

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Abstract

A reciprocating percussion instrument has a housing forming an axially centered chamber having a front end and formed thereat with a pair of adjacent ports, a tool projecting from the housing and exposed axially in the chamber, and a double-acting piston forming front and back compartments and axially reciprocatable between a rear end position and a front end position at least generally in axial engagement with the piston. The piston has a groove forming a fluid-connection path in the chamber between the ports only in the front end position of the piston. A conduit connects one of the ports to one of the sides of the pressure source. A controller includes a pilot line connected to the other of the ports and a distributor valve connected between high- and low-pressure sides of a hydraulic pressure source and the compartments to cyclically alternately pressurize and depressurize the compartments and thereby axially reciprocate the piston between its end positions at a frequency dependent on pressure in the pilot line. A pilot-feed system at least peridocially connects a one of the sides of the source to the pilot line for biasing the pressure of same away from that of the side of the source connected to the conduit.

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First Claim