Comparative Analysis of Electric Drive top drive drilling system and hydraulic driven top drive drilling system.

对比分析电驱动顶驱和液压驱动顶驱.

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The history of top drive drilling system from direct current drive to variable - frequency drive is introduced.

简述了国外钻机顶部驱动系统由直流顶驱逐步演变到变频顶驱的发展历史.

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