| 摘要 |
A sectional drive system for transmitting rotational power to an output, which system includes multiple splined drive segments which are nested and interlocked as a drive string that is rotatable in a selected straight or curved path. The top one of the drive segments cooperates with a drive mechanism to effect rotation of the nested drive segments in concert, and the bottom one of the drive segments connects to a suitable output such as a drill bit. Multiple, tapered and truncated exterior splines on each of the drive segments mesh with complementary interior splines on the adjacent drive segment to enable slight angular positioning of the drive segments on each other and facilitate dampening of drive vibration and bending of the drive string in or out of the chosen path in any desired direction as the drive string transmits rotational power in a curved path of desired magnitude from the drive mechanism to the output. The drive segments are typically connected internally by means of a cable or shaft, or may be connected by floating "collars", to form the drive string. In a preferred embodiment, a drill bit having a removable center bit insert is mounted on the bottom one of the drive segments on the drive string, and is characterized by multiple interior splines which engage the companion exterior splines of the drive segment.
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