Abstract: A finger actuated pump dispenser employs a first upper hollow vertical cylinder with a first diameter and open upper and lower ends and a second lower hollow vertical cylinder with a second and smaller diameter and a closed lower end with a central opening. The lower end of the first cylinder is joined to an open upper end of the second cylinder. The inner wall of the second cylinder has a horizontal annular recess. A first vertical hollow piston has openings in top and bottom ends and extendings slidably above and within first cylinder. The first piston has an enlargement intermediate its ends peripherally engaging and defining a first unbroken seal with the inner surface of the first cylinder. A second vertical piston has a central vertical bore extending therethrough and is disposed slidably within the second cylinder. The second piston peripherally engages and defines a second seal with the inner surface of the second cylinder.

Abstract: A finger actuated pump dispenser employs a first upper hollow vertical cylinder with a first diameter and open upper and lower ends and a second lower hollow vertical cylinder with a second and smaller diameter and a closed lower end with a central opening. The lower end of the first cylinder is joined to an open upper end of the second cylinder. The inner wall of the second cylinder has a horizontal annular recess. A first vertical hollow piston has openings in top and bottom ends and extends slidably above and within the cylinders. The first piston has an enlargement intermediate upper and lower ends peripherally engaging and defining a first unbroken seal with the inner surface of the first cylinder. The first piston has a lower section extending downward from the enlargement to its lower end, the lower section having an outer diameter slightly less than the diameter of the second cylinder.

Abstract: A lower end of a first hollow cylinder is connected to an upper end of a second hollow cylinder. A first outer hollow stem has an intermediately disposed first external enlargement disposed within the first cylinder. A hollow vertical main piston is vertically slidable within the first cylinder. A second inner stem extends upwardly through the main piston and through a bore in the first stem. A space between an upper section of the second stem and the first stem defines a vertical fluid discharge path. An upper end of an integral lower vertical section of the second stem engages the lower end of the main piston so that a horizontal channel extends between the lower section and the lower end of the main piston and connects the region between the lower section and the inner wall of the first cylinder to the fluid discharge path. A fluid discharge port is formed between the upper ends of the first section and the inner stem.

Abstract: The lower end of a first hollow vertical cylinder is connected to the upper end of a second vertical hollow cylinder of smaller diameter. A first outer hollow stem open at its ends has an intermediately disposed first external enlargement disposed below the top open end of the first cylinder. A hollow vertical main piston is vertically slidable within the first cylinder. A second inner stem has an upper vertical section which extends upwardly through the main piston and through a bore in the first stem. A vertical fluid discharge path is formed between the upper section and the first stem. An integral lower vertical section of the second stem engages the lower end of the main piston. A fluid discharge port is formed between the first section and the stem. A vertical inner piston is slidable in the second cylinder. A first spring normally biases the stems together, closing the discharge port. A second spring causes the discharge port to open during a selected point on the downstroke.

Abstract: A finger operated pump dispenser employing interconnected upper and lower cylinders, first and second pistons disposed in the upper and lower cylinders, a hollow sleeve, and a stem which extends upwardly through the first piston into the sleeve. The first cylinder, the stem and the two pistons define a pump chamber which is filled with fluid. When the dispenser is actuated, fluid is displaced from the chamber into the second cylinder and a port is opened. The port can be made to open at the moment that all of the fluid is displaced into the second cylinder. Once the port is opened, the fluid is discharged and further piston movement enables fluid to be pulled upward out of the container secured to the dispenser via an opening formed between the second piston, stem and inner wall of the second cylinder refilling the chamber. The motions of pistons, stem and sleeve are so controlled that accurate dosage is produced independently of the method of actuation.