Liner hanger is a special tool to hang and cement liners. A liner hanger is made up of principle body, running tool and other tools etc for special purpose. Liner hangers are classified as two kinds of mechanical type which completes to hang liner by operating drill string and hydraulic type which completes to hang liner by hydraulic pressure. There are small step type, hydraulic type, guide track type, J-groove type as well as cuniform block type etc used in oil field, and among them, small step type, hydraulic and guide track type liner hanger are widely used.
