04991667 is referenced by 52 patents and cites 7 patents.

Hydraulic drilling method and apparatus in which the drilling fluid itself is utilized to control the direction in which a hole is bored in the earth. The drilling fluid is discharged through a plurality of forwardly facing nozzles which are inclined at different angles about the axis of the drill head, and the drilling fluid is selectively applied to the nozzles by a rotatable valve member to control the direction in which the hole is cut.

Title
Hydraulic drilling apparatus and method
Application Number
7/439659
Publication Number
4991667
Application Date
November 17, 1989
Publication Date
February 12, 1991
Inventor
Ben W O Dickinson III
2125 Broderick St., San Francisco, 94115
CA, US
Michael J Pesavento
2125 Broderick St., Berkeley
CA, US
Paul S Turin
2125 Broderick St., Berkeley
CA, US
Robert D Wilkes Jr
2125 Broderick St., Berkeley
CA, US
Agent
Flehr Hohbach Test Albritton & Herbert
Assignee
Robert Wayne Dickinson
CA, US
Ben Wade Oakes Dickinson III
CA, US
IPC
E21B 7/18
E21B 7/08
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