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Mobile mine-roof support
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Patent number 4,737,051
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Issue date Apr 12, 1988
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Hermann Hemscheidt Maschinenfabrik GmbH & Co.
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Hans Bull
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E21 - EARTH DRILLING MINING
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Sliding supporting gallery
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Patent number 4,348,138
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Issue date Sep 7, 1982
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Charbonnages de France
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Guy Blampain
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E21 - EARTH DRILLING MINING
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Advancing support
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Patent number 4,129,990
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Issue date Dec 19, 1978
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Charbonnages de France
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Alfred Valantin
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E21 - EARTH DRILLING MINING
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Roof support
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Patent number 4,114,385
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Issue date Sep 19, 1978
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Charbonnages de France
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Alfred Alphonse Marie Valantin
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E21 - EARTH DRILLING MINING
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Roof supports
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Patent number 4,109,473
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Issue date Aug 29, 1978
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Charbonnages de France
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Alfred A. Valantin
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E21 - EARTH DRILLING MINING
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Movable roof support mechanism
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Patent number 4,026,118
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Issue date May 31, 1977
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The United States of America as represented by the Secretary of the Interior
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Frank Vernon McCay
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E21 - EARTH DRILLING MINING
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2899800
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Patent number 2,899,800
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Issue date Aug 18, 1959
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E21 - EARTH DRILLING MINING
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2826898
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Patent number 2,826,898
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Issue date Mar 18, 1958
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E21 - EARTH DRILLING MINING
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2752757
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Patent number 2,752,757
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Issue date Jul 3, 1956
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E21 - EARTH DRILLING MINING
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2714505
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Patent number 2,714,505
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Issue date Aug 2, 1955
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E21 - EARTH DRILLING MINING