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.

Abstract: The fluid-power converter of the present invention is a pump-motor having matched rollers and matched gears arranged to provide seals and displacement paths. The pump-motor includes a plurality of rotators in series-contact to define a plurality of fluid-pressure zones. At least one of the rotators has a smooth surface and at least another of the rotators has a gear-like surface. A smooth rotator and a gear-like rotator are in contact with each other to define therebetween a displacement path whereby fluid is transferred from one zone to another zone, and at least one pair of similar rotators are in contact with each other to provide therebetween (and between the pressure zones) a seal to insure fluid-flow in only one direction between the zones at a given moment. A pair of the converters, one operating as a pump and the other as a motor, provide the motive power with free-wheeling and coaster-brake features for small vehicles such as bicycles, wheelchairs, and golf carts.