| 摘要 |
A stabilizer for attachment to a drill string in shaft drilling has an improved bearing. The stabilizer has an inner hub that is rigidly secured to the drill string above the bit. An outer hub encircles the inner hub. The outer hub has a centralizing device that extends laterally outward for frictionally engaging the walls of the shaft if the drill string wanders off-center. The bearing between the inner and outer hubs includes a plurality of rollers rotatably mounted to one of the hubs and in rolling contact with the other of the hubs to allow rotation of the hubs with respect to each other. In the preferred embodiment, the hub opposite the one containing the rollers has frusto-conical rings that are engaged in rolling contact by the rollers. |
