| 摘要 |
A launching device for launching a percussion borer at the start of a ground boring operation comprises a carrier for holding the borer with mounting means which permits the borer to move forwards relative to the carrier in a boring movement but resists backward movement, and a base plate which, in operation, is anchored to the ground and on which the carrier is adjustably mounted. The adjustment of the carrier on the base plate enables the borer to be accurately directed in the correct direction in which the boring is to be made and when the borer is set in operation, rearward impulses on the borer are transmitted through the carrier and the base plate to the ground by which they are counteracted.
|
