"positive displacement mud motor"

Забойный двигатель ПДМ (двигатель объемного типа) для наклонно-направленного и горизонтального бурения

A downhole motor (also known as a positive displacement motor, PDM, or mud motor) is a downhole drilling tool that converts the hydraulic power of drilling fluid into mechanical power to rotate the drill bit . Unlike conventional rotary drilling where the entire drillstring rotates from the surface, ...