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Publication of DE187527CpublicationCriticalpatent/DE187527C/de
Tiefbohrvorrichtung zum Drehbohren mit Elektromotorantrieb fuer das Bohrwerkzeug undSchmandfaenger in einem Gehaeuse, das durch ein stromfuehrendes Kabel in das Bohrloch hinabgesenkt und in der Arbeitslage gegen Drehung im Bohrloch gesichert ist