Title:
Drilling head assembly
United States Patent 3400938


Inventors:
Bob, Williams
Application Number:
US58691266A
Publication Date:
09/10/1968
Filing Date:
09/16/1966
Assignee:
BOB WILLIAMS
Primary Class:
Other Classes:
166/84.3, 175/214, 277/346, 277/510, 277/549
International Classes:
E21B21/16; E21B33/08
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