在线免费观看一区二区三区,一区二区欧美视频,在线日韩欧美一区二区三区,亚洲经典一区二区三区,椎名空中文字幕一区二区,亚洲女同一区二区,一区二区在线视频免费观看

    Drill-stem rotation is ordinary means that the rotary table drives the kelly in petroleum, nature gas,geological exploration and drilling engineering. In some conditions,for example, the kelly is not in the rotary table, the drillpipe rotary tool in parts is necessary uesd to drive the kelly.

Technical parameters and specifications