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Josef Welzel
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Wuppertal, DE
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last 30 patents
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Patent Grant
Method of electro-hydraulic control of longwall mine units
Patent number
4,964,675
Issue date
Oct 23, 1990
Herman Hemscheidt Maschinenfrabrik GmbH & Co.
Josef Welzel
E21 - EARTH DRILLING MINING
Information
Patent Grant
3-Port, 2-position directional control valve
Patent number
4,505,299
Issue date
Mar 19, 1985
Hermann Hemscheidt Maschinenfabrik GmbH & Co.
Josef Welzel
E21 - EARTH DRILLING MINING
Information
Patent Grant
Mine-roof support
Patent number
4,380,410
Issue date
Apr 19, 1983
Hermann Hemscheidt Maschinenfabrik GmbH & Co.
Hans Bull
E21 - EARTH DRILLING MINING
Information
Patent Grant
Roof-support distancing apparatus
Patent number
4,330,226
Issue date
May 18, 1982
Herman Hemscheidt Maschinenfabrik GmbH & Co.
Josef Welzel
E21 - EARTH DRILLING MINING