| 摘要 |
The screw base has a base body with cylindrical regions and a tunneling element, which is formed from multiple sand shovels (2) arranged around the circumference of the screw base. The sand shovels are provided with different diameters and inclinations. A drill bit is arranged in the cylindrical regions of the base. A retaining ring is attached at upper surface of the base body on outer side. A stabilization element is arranged below the retaining ring and has disks, whose external dimension is larger than external dimension of the base body. The shovels have sand shovel segments (2.1-2.7). |
