| 摘要 |
<p>Appts. has two members each able to rotate about their own longitudinal axis. The axes cross at an angle. The members are connected by a universal joint (26,31,32). A wt. (57) holds the one axis in place when both members rotate. A directional drilling appts. as above is also claimed in which the first member is a shaft (27) with a drill bit (11) on one end, the second member is tubular housing (21) rotated by a drill string and the wt. holds the first axis so the bit faces in one direction when the housing rotates.</p> |
