CPC E21B 23/0416 (2020.05) | 13 Claims |
1. A control unit comprising:
a spindle;
a tubular body rotatable relative to the spindle, the tubular body including a plurality of fins;
a torque transfer unit having a first member attached to the spindle and a second member attached to the tubular body, the first member having a first bearing surface and the second member having a second bearing surface, the first bearing surface and the second bearing surface contacting each other with a friction force; and
a torque generator configured to apply a torque to the spindle.
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