Mud Motor consists of a power section and a bearing section.

The bearing section is assembled with the following to impart a bend to a motor:
• Adjustable bent housing assembly — for DRU motors. The adjustable bent housing assembly allows rig floor bend adjustment.
• Bent sub — for DOT motors. The motor bend is adjusted by changing the bent sub. For a straight motor, a straight sub is used instead of a bent sub.

The hydraulic downhole motor is a volumetric (hydrostatic) machine. Torque output and rotary speed depend on the number of rotor and stator lobes (lobe configuration). The more lobes, the lower the speed and the higher the torque. Speed, torque output, power, differential pressure are proportional to the flow rate of the drilling fluid. The longer the motor with respectively more stages, the higher the horse power and torque output of the motor.