ALLWEILER® and IMO® three-screw pumps are rotary, self-priming positive displacement pumps. The pumping element consists of three moving parts: the power rotor (main screw) and two symmetrically opposite idler rotors, both operating within a tightly fitting housing bore. Incoming process fluid is conveyed by the rotating power rotor through the cavity formed by the intermeshing idler rotor.

From suction to discharge, the fluid is transported through a series of chambers that are continuously shaped and reshaped until it reaches the casing outlet. Symmetrical pressure loading on the power rotor eliminates the need for radial bearings to absorb radial forces. The idler rotor creates a hydrodynamic film that provides radial support similar to a radial bearing. Axial loads on the power rotor and idler rotor are generated by pressure differences and are hydrostatically balanced. With this design arrangement, high pressure differentials can be managed.

Main use: For use in all industrial areas pumping lubricants that do not contain abrasive components and do not chemically attack the pump materials, such as the circulation of heavy and diesel oils, lubricating oils and hydraulic oils.