turbo-foreuse

CONT: La turbo-foreuse est une turbine à étages multiples entraînant directement les trépans à molettes [...] Elle est actionnée par la circulation de la boue, dont le débit et la pression sont adaptés à cet usage. Les tiges sont alors immobiles ou tournent lentement pour supporter la réaction du couple moteur.

CONT: There are two types of turbodrill or down-hole mud motor: the turbine, of which there are about six successful types, and the Dynadrill, a Moyno pump operating in reverse, consisting of a spiral shaft contained within a rubber sleeve. ... The down-hole turbine is basically similar to a gas turbine having a multi-stage stator and rotor.
CONT: When a turbodrill is used, rotary motion is imparted only at the bit; therefore, it is not necessary to rotate the drill stem. Although straight holes can be drilled with the tool, it is used often in directional drilling.