A versatile device is provided for securely gripping the outer surface of a cylindrical object and pulling it against a resistant force comprising a sleeve that fits around the cylindrical object and engages its outer surface with gripping jaws when a pulling force is applied. The extractor enables efficient and economical extraction of soil access tubes without tube damage. The device can be operated either with large power equipment or with a manual jack.
申请公布号
US5072981(A)
申请公布日期
1991.12.17
申请号
US19900603505
申请日期
1990.10.26
申请人
THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY OF AGRICULTURE;COLORADO STATE UNIVERSITY RESEARCH FOUNDATION