发明名称 ELEVATOR/SPIDER WITH COUNTERBALANCE
摘要 <p>An elevator/spider having a series of slips in a tapered bowl and a yoke for pivotally setting slips a torsion spring is mounted on the body of the elevator/ spider. A wire rope connects the torsional spring to the yoke, so that the weight of the slips is counterbalanced by the force of the torsional spring.</p>
申请公布号 CA1218644(A) 申请公布日期 1987.03.03
申请号 CA19840466482 申请日期 1984.10.29
申请人 HUGHES TOOL COMPANY 发明人 BERG, GUNNAR H.
分类号 E21B19/07;E21B19/10;(IPC1-7):E21B19/10 主分类号 E21B19/07
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