Abstract: An air driven diaphragm pump includes two diaphragms affixed to a common shaft. The shaft extends through an air valve providing reciprocating pressurized air to the diaphragms through associated air chambers. A pump chamber with intake and exhaust valves is associated with one of the two diaphragms while a further air chamber replaces a pump chamber and is associated with the other of the diaphragms. A passage extends through the shaft and is in communication with the air chamber adjacent to the pump chamber and with the further air chamber converted from the pump chamber.

Abstract: A multi-stage rotary compressor to reduce a driving load and prevent a malfunction due to an abrupt pressure rising. In the compressor of the type including first and second compressing units mounted in a hermetic casing thereof to compress a gas, the gas being primarily compressed in the first compressing unit and secondarily compressed in the second compressing unit, the interior of the hermetic casing is divided into a plurality of spaces including first and second pressure chambers. The first pressure chamber surrounds the first compressing unit and is kept at a discharge pressure of the first compressing unit, and the second pressure chamber surrounds the second compressing unit and is kept at a discharge pressure of the second compressing unit.

Abstract: A pumping device includes a container having a cover structure. A piston is movably received in the container and is manually operable. The cover structure has an air inlet valve and a slide switch, which, when properly set, allow air to be sucked into or expelled out of the container by the manual operation of the piston to increase or decrease the internal pressure of the container for oil suction and oil drainage. The pumping device also includes another slide switch, whereby when both slide switches are properly set, the internal pressure of the container is increased or decreased due to the supply of pressurized air from an external source and oil can be sucked into and drained out of the container accordingly.