Invention Grant
- Patent Title: Indicating device for well drills
- Patent Title (中): 钻井指示装置
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Application No.: US30979539Application Date: 1939-12-18
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Publication No.: US2300823APublication Date: 1942-11-03
- Inventor: WHITMAN ALVIN D
- Applicant: WHITMAN ALVIN D
- Assignee: Alvin D Whitman
- Current Assignee: Alvin D Whitman
- Priority: US30979539 1939-12-18
- Main IPC: E21B25/02
- IPC: E21B25/02 ; E21B47/00 ; E21B47/12 ; G01V9/00
Information query
