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Mine roof supports
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Patent number 4,518,284
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Issue date May 21, 1985
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Gewerkschaft Eisenhutte Westfalia
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Kunibert Becker
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E21 - EARTH DRILLING MINING
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Slidable filling dam
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Patent number 4,406,565
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Issue date Sep 27, 1983
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Centrum Konstrukcyjnotechnologiczne Maszyn Gorniczych
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Wincenty Pretor
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E21 - EARTH DRILLING MINING
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Mine roof support assembly
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Patent number 4,217,067
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Issue date Aug 12, 1980
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Gewerkschaft Eisenhutte Westfalia
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Gunter Lagodka
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E21 - EARTH DRILLING MINING
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Mining method and apparatus
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Patent number 4,102,550
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Issue date Jul 25, 1978
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Peabody Coal Company
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John A. L. Campbell
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E21 - EARTH DRILLING MINING
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Hydraulic shield assembly
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Patent number 4,064,701
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Issue date Dec 27, 1977
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Herman Hemscheidt Maschinenfabrik
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Hans-Otto Friedrichs
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E21 - EARTH DRILLING MINING
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Mine roof supports
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Patent number 4,041,714
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Issue date Aug 16, 1977
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Gullick Dobson Limited
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Archelaius Dawson Allen
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E21 - EARTH DRILLING MINING
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3779023
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Patent number 3,779,023
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Issue date Dec 18, 1973
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E21 - EARTH DRILLING MINING
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3466875
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Patent number 3,466,875
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Issue date Sep 16, 1969
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E21 - EARTH DRILLING MINING
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3438209
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Patent number 3,438,209
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Issue date Apr 15, 1969
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E21 - EARTH DRILLING MINING
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3399927
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Patent number 3,399,927
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Issue date Sep 3, 1968
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E21 - EARTH DRILLING MINING
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3143862
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Patent number 3,143,862
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Issue date Aug 11, 1964
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E21 - EARTH DRILLING MINING