Title:
Drilling device
United States Patent 3162253
US Patent References:
Motor operated drill
- - 2730332

Drill steel centralizer for coal drill
- - 2788194

Mobile rock drill rig
- - 2845251

Mine drilling machine
- - 2958514


Inventors:
Curtis, John C.
Publication Date:
12/22/1964
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Assignee:
JOY MFG CO
Primary Class:
173/147
Other Classes:
173/195, 74/89.120, 137/355.160
International Classes:
E21B15/04; E21B19/22; E21B15/00; E21B19/00
Foreign References:
GB220790A