Rotation and circulation is done at the top of the drill string.  A top drive is a hydraulic or electric motor suspended in the derrick or mast of a drilling rig.  The drilling rig top drive works by rotating the drill string without the use of a kelly and rotary table.  Top drives provide better safety and efficiency while reducing manual labor, and reduce the frequency of stuck pipe.  The top drive drilling system is operated from a control console on the rig floor. Our drilling rigs have top drives in the following capacities, listed from largest to smallest:

• 1200 hp w/
  750 ton capacity AC motor
• 1000 hp w/
  500 ton capacity AC motor
• 800hp w/
  500 ton capacity AC motor
• 1000hp w/
  350 ton capacity AC motor
• 600hp w/
  275 ton capacity AC motor
• 400hp w/
  175 ton capacity AC motor