| 摘要 |
A downhole tool assembly 5000, comprising a first body 5051 and a second body 5052 arranged to rotate one relative to the other about a rotation axis 1000 and a drive arrangement 1001 between the first and the second body for rotating bodies relative to each other. The drive arrangement may comprise a planetary gearbox or a Harmonic drive 5053 comprising a wave generator 5054, a flexible gear 5055 and an outer circular gear 5056, wherein one of the inner gear, flexible gear and outer gear is adapted to function as a rotary input component and another is adapted to function as a rotary output component. The downhole tool assembly comprises at least one motor for rotating another component of the downhole tool assembly, e.g. a drill bit. A directional drilling tool is described having a first harmonic drive or planetary gearbox between swivel members and a second harmonic drive or planetary gearbox between bend members.
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