Impellers 1 and 2 rotate about fixed axes A and B and have symmetrically arranged pin-shaped teeth d and mushroom-shaped teeth e. When impellers 1 and 2 rotate, fluid is continuously delivered in the direction of arrows a and b. The suction and discharge chambers are separated by imparting special profiles to teeth d and e. The impellers are driven by two meshing identical gears keyed to the shafts of impellers 1 and 2.
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