Blackmer’s S Series Screw Pumps are self-priming double ended positive displacement pumps that are offered with or without external timing gears and bearings. Our twin and triple screw designs provide complete axial balancing of the rotating screws and with our timing technologies eliminate metal-to-metal contact within the pump. Blackmer’s carefully crafted screw technology rotates within a cylindrical cavity, transferring fluid and materials along the screw’s spindle.