| 摘要 |
A machine for driving and extracting piling and the like having a horizontal support member and frame coupled so that the frame may move toward and away from the support member in a vertical direction, a pair of races located side by side in the frame and defining a corresponding pair of paths of travel spaced horizontally from each other and located in a common vertical plane, a relatively heavily weighted roller mounted for rotation within each race, each roller being rotatable about a horizontal axis perpendicular to the common vertical plane, means for rotating the weighted rollers in synchronism such that the horizontal components of the forces generated on the frame by the rollers cancel one another and the vertical components of the forces are in phase to thereby simulate the impact of a conventional reciprocating pile hammer.
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