Abstract: A pressure for a chamber is regulated by controlling either the exhaust pressure at the exhaust side of a first vacuum pump or the internal pressure at a compression stage of the first vacuum pump, where the first vacuum pump is directly communicating with the chamber. The pressure of the chamber can be regulated by combinations of the following: controlling the variable rotational frequency of a roots vacuum pump, a pre-vacuum pump, or a high compression pump; controlling a control valve between a pre-vacuum pump and the first vacuum pump; controlling a control valve for injecting gas into the exhaust side of the first vacuum pump or into the compression stage of the first vacuum pump; and controlling a control valve or control valves for bypassing the first vacuum pump or a compression stage or compression stages of the first vacuum pump.

Abstract: An oil supply device has a reservoir adapted to contain oil having a predetermined oil level; a drive shaft extending into the reservoir; a disc affixed to the shaft and being arranged to be submerged at least partially in the oil contained in the reservoir; and a trough affixed to the disc for rotation therewith as a unit. The trough extends arcuately and is radially inwardly open as viewed relative to the disc. Further, the trough is arranged to be submerged at least partially in the oil contained in the reservoir. There is also provided an oil conduit having a stationarily supported terminal portion accommodated in the reservoir and projecting into the trough. The oil conduit is provided with an open end situated in the trough and oriented opposite an operational rotary direction of the disc, whereby oil is driven into the terminal portion through the open end from the trough upon rotation of the drive shaft to supply oil under pressure in the oil conduit.

Abstract: A twin-shaft pump includes a working chamber; a first side plate and an opposite, second side plate bounding the working chamber; and two impellers accommodated in the working chamber and each having a first end face and an opposite, second end face. Each first end face is adjacent and oriented toward the first side plate and each second end face is adjacent and oriented towards the second end plate. There are further provided impeller bearings adjacent the first and second end faces of each impeller; and a pump drive situated adjacent the first end faces and being operatively connected to the impellers. A dish-shaped component is situated adjacent at least one of the end faces of at least one of the impellers. The dish-shaped component has an inner wall defining a dish-shaped cavity accommodating an impeller bearing which is in a supporting contact with the inner wall of the component.

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: In a vacuum pump having a housing presenting a suction side and a pressure side, a connecting line connected between the suction side and the pressure side and a weighted valve mounted in the connecting line and having a part which is movable to open the valve in order to place the suction and pressure sides in communication when a maximum permissible pressure difference between the suction and vacuum sides is exceeded, the valve is mounted so that the axis of movement of the valve part forms an angle of 45.degree. with the direction of the pumping action between the suction and pressure sides, whereby the weighted valve will function properly with the pump oriented to produce its pumping action in either the vertical or the horizontal direction.