The Sling Pump, with only one moving
part, is a modern application of an Archimedes Snail Pump. A helical intake coil
is wrapped around and around the inside surface of a cone. The coil is connected
to an output tube via a water-lubricated swivel coupling at the extreme upstream
side of the pump and is open at the downstream (fat) end. The downstream end of
the cone has slats to let water in but keep debris out. A rope or pair of ropes
holds it in place.
The pump floats partially submerged, being largely of plastic,
with aluminum propeller blades and bouyant styrofoam in the nose. With each revolution
of the cone, the coil picks up air during the top portion of the cycle and water
during the bottom portion. This causes a pulsed output, and also means the output
water is highly oxygenated. The Rife Hydraulic Engine Mfg. Co., Inc. claims some
models of their Sling Pumps (inset) can raise water over 80 feet high or move
it a mile horizonally, from a stream moving at just 1.5 feet per second. (Head
doesn't change with speed, only volume.) The unit weighs about 44 lbs. and uses
a 1/2" hose.