Mud motor, also known as drilling motor, is a device used in geological drilling. Technically speaking, the mud motor is a screw type positive displacement pump, which transports fluid through the rotation of a screw transmission. When rotating, the "spiral" shape of the device can push liquids and solids at the same time. Mud motors are slightly different, because drilling fluid or compressed gas is used to generate eccentric motion in the mud motor, and this eccentric motion is converted into concentric motion, which causes the drill bit to rotate.