Abstract: A gear pump is described for pumping extremely low volumes of fluid at extremely low rates of flow. The pump includes a housing with a cavity therein and a pair of gears rotatable within said cavity. One of the gears is shafted and the other is shaftless, and the gears are made of resilient material with the diameter of the periphery of the tips of the gear teeth exceeding the diameter of the cavity in which they rotate. The face width of the gears also exceeds the depth of the cavity in which they rotate.
Abstract: This invention resides in a closed system, with permanently fixed end plates, which permits the pump-motor of the present invention to operate either as a combined pump-motor, or as a pump only, or solely as a motor. Rotators of this invention have parallel axes normal to the end plates which they intersect at fixed coordinates. That makes possible direct drive to or from a rotator shaft extension or the enclosing cylindrical rotator.In the device of this invention, the end-plates are non-rotary, but the cylindrical shell or housing always rotates. The plurality of rotators within the cylinder define a plurality of fluid pressure zones. Some of the rotators have a relatively smooth surface; the others have relatively gear-like surfaces. When the unit operates as a pump, a shaft extension of one of the rotators protrudes through one of the end plates and is coupled with an input power source such as the crank or pedals of a bicycle.