Downhole Rotational Lock Mechanism

A method for transmitting rotational torque to a downhole tool, comprising:

• providing a downhole rotational lock mechanism, including
• a tubular housing having a longitudinal bore with an internal wall;
• a driving gear disposed in the longitudinal bore of the tubular housing, said driving gear having a peripheral edge secured to the internal wall of the longitudinal bore of the tubular housing, said driving gear having an upper portion including a first plurality of gear teeth disposed around a central longitudinal bore through the driving gear;
• a driven gear movably disposed in the longitudinal bore of the tubular housing, said gear having a central longitudinal bore, said driven gear having a lower portion including a second plurality of gear teeth;
• and
• an output drive shaft disposed longitudinally in the longitudinal bore of the tubular housing and in the longitudinal bore of the driven gear;
• rotating the tubular housing and the driving gear at a first rotational speed in a first rotational direction;
• rotating the output shaft and the driven gear at a second rotational speed less than the first rotational speed and in the first rotational direction;
• engaging the driven gear with the driving gear;
• and
• transferring rotational torque from the driving gear to the driven gear.

A method for transmitting rotational torque to a downhole tool, comprising:

• providing a downhole rotational lock mechanism, including
• a tubular housing having a longitudinal bore with an internal wall;
• a driving gear disposed in the longitudinal bore of the tubular housing, said driving gear having a peripheral edge secured to the internal wall of the longitudinal bore of the tubular housing, said driving gear having an upper portion including a plurality of gear teeth disposed around a central longitudinal bore through the driving gear;
• a driven gear movably disposed in the longitudinal bore of the tubular housing, said gear having a central longitudinal bore, said driven gear having a lower portion including a plurality of gear teeth;
• and
• an output drive shaft disposed longitudinally in the longitudinal bore of the tubular housing and in the longitudinal bore of the driven gear;
• rotating the tubular housing and the driving gear at a first rotational speed in a first rotational direction;
• rotating the output shaft and the driven gear at a third rotational speed greater than the first rotational speed and in the first rotational direction;
• disengaging the driven gear from the driving gear;
• and
• discontinuing the transfer rotational torque from the driving gear to the driven gear.