Patent ID: 6883620

Claim:
A device for supplying hydraulic power to a percussive rotary drilling apparatus including a tool, a rotational drive device for rotating the tool, and an impact device for reciprocating the tool independently of the rotation, the device supplying hydraulic power via a hydraulic liquid under pressure, the device comprising: a flow splitter that pressurizes and separates a flow of the hydraulic liquid into at least a first portion and a second portion; a plurality of distributors that control the supply of the pressurized hydraulic liquid from the flow splitter; a plurality of pipes that supply the pressurized hydraulic liquid between the distributors, and the drive device and the impact device, the plurality of pipes including: an impact device supply pipe that supplies the first portion of the pressurized hydraulic liquid to the impact device; a return pipe that returns the second portion of the pressurized hydraulic liquid from the rotational drive device to the impact device supply pipe; an external pipe connecting the return pipe and the impact device supply pipe so that the second portion of the pressurized hydraulic liquid flowing through the return pipe may be added to the first portion of the pressurized hydraulic liquid flowing through the impact device supply pipe, wherein the external pipe is located externally of the percussive rotary drilling apparatus.