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-
-
-
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3851481
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Patent number 3,851,481
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Issue date Dec 3, 1974
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E21 - EARTH DRILLING MINING
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3812680
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Patent number 3,812,680
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Issue date May 28, 1974
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E21 - EARTH DRILLING MINING
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3547493
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Patent number 3,547,493
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Issue date Dec 15, 1970
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E21 - EARTH DRILLING MINING
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3295330
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Patent number 3,295,330
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Issue date Jan 3, 1967
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E02 - HYDRAULIC ENGINEERING FOUNDATIONS SOIL SHIFTING
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1800819
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Patent number 1,800,819
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Issue date Apr 14, 1931
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E21 - EARTH DRILLING MINING
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1702646
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Patent number 1,702,646
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Issue date Feb 19, 1929
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E21 - EARTH DRILLING MINING
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1644476
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Patent number 1,644,476
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Issue date Oct 4, 1927
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E21 - EARTH DRILLING MINING
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1583075
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Patent number 1,583,075
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Issue date May 4, 1926
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E21 - EARTH DRILLING MINING
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1388698
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Patent number 1,388,698
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Issue date Aug 23, 1921
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E21 - EARTH DRILLING MINING
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1382668
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Patent number 1,382,668
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Issue date Jun 28, 1921
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E21 - EARTH DRILLING MINING