F
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F04
POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
F04C
ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
F04C18/00
Rotary-piston pumps specially adapted for elastic fluids
F04C18/02
of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
F04C18/0207
both members having co-operating elements in spiral form
F04C18/0215
where only one member is moving