appareil de forage à entraînement par le haut

CONT: L'exploitant veille à ce que [...] dans le cas d'un appareil de forage à entraînement par le haut, les deux vannes, inférieure et supérieure, soient manœuvrables à la main [...]

CONT: Introduced by Varco in 1982, the Top Drive Drilling System (TDS) revolutionized oil and gas drilling, replacing the traditional rotary table approach on virtually all offshore rigs with dramatic gains in drilling productivity and safety.
OBS: top drive: A device similar to a power swivel that is used in place of the rotary table to turn the drill stem. It also includes power tongs. Modern top drives combine the elevator, the tongs, the swivel, and the hook. Even though the rotary table assembly is not used to rotate the drill stem and bit, the top-drive system retains it to provide a place to set the slips to suspend the drill stem when drilling stops.