Steerable tunnel-drilling machine
United States Patent 3295892

Inventors:
Winberg, Douglas F.
John, Galgoczy
Publication Date:
01/03/1967
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Assignee:
ROBBINS & ASSOC JAMES S
Primary Class:
299/31
Other Classes:
299/56, 175/99, 175/94
International Classes:
E21D9/10
Foreign References:
GB852537A
GB889943A