Exit Pit

An opening located at the exit of the cutting head or casing.

Exit Seal

Same as a launch seal except for the retrieval of the machine at the reception shaft. Used in high groundwater and unstable soils to prevent loss of ground.

Expander

A tool which enlarges a bore during a pull-back operation by compression of the surrounding ground rather than by excavation. Sometimes used during a thrust boring process as well as during directional drilling/guided boring pull-back.

Extension Track

An additional section of track used in front of the master track.