Mud Motor Bearing and Drive Shaft Assembly:

The drive shaft is one of the mud motors components which is a rigidly-constructed hollow steel component. It is supported within the bearing housing by radial and axial thrust bearings . The bearing assembly transmits drilling thrust and rotational power to the drill bit. Most of the mud flows straight through the center of the drive shaft to the bit.
The bit sub is attached to the drive shaft. When pumping through the motor, the drive shaft will turn the bit sub and the bit.