The screw pump is a positive displacement
pump which comes with two or three screws. (A single screw version is called a
"progressing cavity" pump.) The Quimby Screw Pump is a type of screw pump.
The pump forms hollow cavities which contain the fluid and move it along the
screws. One screw is the drive screw and the other screw or screws is/are driven
by the drive screw.
The two-bladed pump shown here has had a plexiglass casing
put on so that the internal gearing can be seen. This pump was manufactured by
Leistritz.
(Photo by the author.)
