Abstract: A two-stage vacuum pump apparatus has a first stage of vacuum pump constituted by a screw-type vacuum pump and a second stage vacuum pump constituted by an oil-sealed rotary vacuum pump operative to maintain the back pressure of the first stage vacuum pump at a level ranging from 1 to 100 Torr., whereby a high level of vacuum can be attained in a system to be evacuated without any risk of contamination of the evacuated system by oil. Also disclosed is a method of operating the two-stage vacuum pump apparatus.

Abstract: A two-shaft vacuum pump which draws gas in at an inlet and compresses it at a first outlet for discharge, thereby producing a vacuum at the inlet, has a second, pressure-responsive outlet from the area where the gas is compressed for discharge from the first outlet. The second outlet thereby relieves excess, compression gas pressure which could overload the pump motor, for example, at the start of operation when high-density gas is drawn in for compression.

Abstract: A tandem pump arrangement is disclosed comprising a first pump having two meshing gears of different pitch diameter adapted to produce pumping action by their meshing engagement upon drive to the one gear having the larger pitch diameter and the drive thereby of the other gear having the smaller pitch diameter at a higher speed. A second pump has an input connected to be driven by the gear with the smaller pitch diameter with the result that the second pump is driven through the first pump at increased speed with an overdrive ratio determined by the ratio of the pitch diameters of the gears.

Abstract: A rotary engine is comprised of at least one rotor assembly including a drum rotor and a cylinder rotor in internal contact with the drum rotor. The drum rotor bounds, with the cylinder rotor, and a crescent shaped working chamber and an annular working chamber, with the inner surface of the housing. The annular working chamber includes a first segmented annulus portion, a second segmented annulus portion of greater width than the first portion, and a transition portion of gradually increasing width connecting one end of first and second segmented annulus portions. A portion of the inner surface of the housing is inwardly projected between another end of first and second segmented annulus portions to come into contact with the periphery of the drum rotor.

Abstract: A vane-type rotary pump and a vane-type rotary compressor are integrated into a single unit and are driven by a common shaft. The compressor assembly is positioned at the rear of the pump assembly to minimize the number of mechanical seals required to seal the pump assembly along the shaft. The combined pump and compressor unit is provided with a regulating mechanism for reducing the compressor output during moderate or off modes of the refrigerant circuit.

Abstract: A mechanical pump includes a pumping chamber through which extends a pair of parallel shafts 3. Each shaft 3 carries in tandem rotors 4, 5 and 6 at least two of which are the intermeshing "claw" type. The rotors are arranged in complementary pairs and each pair occupies a separate location in the pumping chamber. Each "claw" type rotor 6 of a complementary pair in one location is mounted on its shaft 3 in reverse orientation to the "claw" type rotors 5 of the complementary pairs in the adjacent location.