Quimby Screw Pumps use closely matched screws
which mesh to form pockets of fluid. Each shaft has a left-hand screw and a right-hand
screw, for hydraulic pressure balance. On the left is a side view. The animation
on the right is a top (or bottom) view. The inlet is at each end and the outlet
is in the middle. The two shafts are geared together and revolve at the same rate,
up to about 1750 RPM.
Quimby Screws often pump oil, which lubricates the meshing
gears. They have no valves or small parts to wear out or break, and the stuffing
boxes are in the low pressure part of the pump where they are less prone to wear.
A Quimby Screw can pump 4,000 gallons per minute at 1,000 P.S.I.
