0335543-A1 is referenced by 20 patents and cites 11 patents.

Drilling apparatus comprises a hollow drill pipe (2) extending through a drill hole (4) to a mud motor (8). The motor (8) drives a compressor (12) through a shaft (14). An annular passageway (16) around the compressor (12) leads to a drill bit (18) having nozzles (20) providing an outlet from the passageway (16). A housing (22) of the compressor (12) provides a passageway (24) for leading fluid through the compressor (12) to emerge through nozzles (26) in the drill bit (18) at increased pressure to assist the drill bit (18).

Title
Drilling apparatus.
Application Number
EP19890302703 19890320
Publication Number
0335543 (A1)
Application Date
March 20, 1989
Publication Date
October 4, 1989
Inventor
Walker Colin
Assignee
Pilot Drilling Control
GB
IPC
F04C 05/00
E21B 21/00
E21B 07/18
E21B 04/02
F04C 05/00
E21B 21/00
E21B 07/18
E21B 04/00
F04C 05/00
E21B 21/00
E21B 07/18
E21B 04/02
E21B 04/00
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