Title:
Drilling device
United States Patent 3162253
Inventors:
Curtis, John C.
Publication Date:
12/22/1964
Export Citation:
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Assignee:
JOY MFG CO
Primary Class:
173/147
Other Classes:
74/89.12, 137/355.16, 173/195
International Classes:
E21B7/02; E21B15/04; E21B19/22; E21B7/02; E21B15/00; E21B19/00
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US Patent References:
2958514Mine drilling machine
2845251Mobile rock drill rig
2788194Drill steel centralizer for coal drill
2730332Motor operated drill
Foreign References:
GB220790A