Motor-driven progressive cavity pumps include a motor. They use a helix-shaped rotor and an elastomer stator to dose or transfer liquids in a system. The rotor turns within and against the walls of the stator to create sealed pockets full of liquid, moving the contents through the pump. Progressive cavity pumps have a constant flow rate and operate without pulsation dampeners. They're suited for handling viscous liquids and put minimal shear pressure on fluids.