Abstract: A rotary pump comprising a stator body having a bore and a rotor assembly mounted eccentrically in the bore to form a cavity between the stator body and the rotor assembly. The rotor assembly has two blades slidably positioned in diametrically opposed slots in the rotor assembly. In use of the pump the two blades are substantially in contact with an inner wall of the stator body. The stator body has an inlet and an outlet to allow, in use of the pump, fluid being pumped to enter into and be expelled from the cavity by means of the rotating vanes. The rotor assembly is of integral construction with each slot defined therein having an arcuate base and each blade has an end portion substantially conforming to the arcuate slot base.

Abstract: The present invention provides a sealing arrangement for effecting a seal with a rotatable shaft having with respect to its longitudinal axis a generally cylindrical shape but with a portion thereof of conical shape, which comprises a shaft seal positioned so that its sealing lip engages the shaft and so that any liquid escaping from a first (liquid) side of the seal to a second (air) side of the seal enters an annular cavity formed on one side by the conical portion of the shaft whose cross-sectional diameter decreases in a direction away from the sealing lip on the second side.

Abstract: A mechanical pump having a pumping chamber within which is positioned a pair of intermeshing rotors, preferably of the claw type, with each rotor mounted for rotation on respective shafts and the first rotor being associated with an inlet to the pumping chamber and the second rotor being associated with an outlet from the pumping chamber, wherein the second rotor has a cavity in its surface immediately adjacent the outlet.

Abstract: A vacuum pump comprising a pumping chamber having an inlet and an outlet through which gas from an enclosure connectible to the inlet can be pumped, in which means are provided to allow the selective introduction through the chamber of a flow of recirculating purge gas to effect pumping of the chamber, the means preferably being such that the recirculating purge gas is produced in a gas circuit including the inlet and the outlet and also including a filter.

Abstract: In an oil free mechanical pump of the type in which two shafts support at least one pair of intermeshing rotors for rotation in opposite angular directions, a flexible drive means in the form of the belt or chain is provided for engaging pulleys or sprockets on the shafts.

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.

Abstract: A high-speed rotary vacuum pump has a compression chamber which is spaced from the walls of a housing by at least one body of acoustic insulation material which acts to absorb noise, to position the chamber with respect to the housing, and to form a fluid-tight seal between the chamber and the housing in the region where the rotary drive shaft of the pump projects from the compression chamber. The drive shaft and the gas inlet and outlet ducts are also acoustically insulated.