"RDS1287915601" . "mvsen" . . "Recorded" . "TOP DRIVE DRILLING SYSTEM" . "RDS" . "2009.12.02" . "TOP DRIVE DRILLING SYSTEM" . "A 'well drilling system' and an 'artefact' in which the motor which turns the drill string is connected to the upper end of the string and moves downwardly with the drill string during the drilling operation." . "mvsen" .