Abstract: In a displacement machine for compressible media having at least two rotors (14a-c) which are configured as profiled bodies and whose profiles engage with one another in the manner of gearwheels during rotation, the individual rotors are respectively driven by their own electric motors (9a-c) and are kept synchronous in rotational speed and angular position by electronic closed-loop and/or open-loop control units (1; 25a-c) in accordance with the transmission ratio of the displacer unit stage. The electronics can be employed for monitoring further operating data of the pump and also for matching the pump output by changing rotational speed. It can also be used as an overload protection. The rotational speeds and rotational attitudes of the rotors are controlled individually and independently of one another, the required attitude values being specified to the individual control units (25a-c) by means of a main control unit (1).

Abstract: A dual rotor Roots type vacuum pump has an improved rotor profile contour resulting in high area efficiency, high volumetric efficiency, reduced backstreaming and simplified economical manufacturing which yields a compact, cost effective pump.

Abstract: A double-shaft vacuum pump with pistons (3,4) rotating without contact in the pump chamber (8) and with synchronization gears (16, 17) located in a side chamber (15). In order to dispense with an oil supply in the side chamber the teeth of the synchronization gears (16, 17) are shaped in such a way that contact between the tooth flanks (26) is limited to the immediate vicinity of the pitch circle (29). If any lubrication is needed, it can be supplied by bearing grease suitable for vacuum applications. The side chamber cover (27) is preferably shaped as a "figure-8" to conform to the peripheries of the synchronization gears (16, 17), and a cooling system for the gears may be provided.

Abstract: A twin-shaft vacuum pump includes a pump chamber, a pair of rotary pistons disposed in the pump chamber, and plates which laterally delimit the pump chamber, and a housing ring which peripherally delimits the pump chamber. In order to increase the ability of the pump to withstand thermal stresses, the housing ring and the rotary pistons are made of different materials, with the coefficient of expansion of the piston material being lower than the coefficient of expansion of the housing material. Other improvements include cooling of the lateral end plates, cooling of the rotors, and the provision of sleeves which serve to fix the position of the rotors on the shafts and which are composed of a material whose coefficient of expansion is lower than that of the rotor material.

Abstract: A dual-shaft machine comprising a housing, two pistons rotatably mounted in the housing leaving a cold play spacing between one another and said housing, and a coating provided on either the housing or the pistons, or both, to reduce the cold play spacing to that required by the intended field of use of the machine.

Abstract: A twin-shaft vacuum pump having a pair of shafts, at least one pump chamber, a pair of rotors disposed in the or in each pump chamber and mounted on the shafts, and housing members defining the pump chamber or chambers, a synchronization mechanism composed of two gears disposed in a side chamber, a drive motor, and a transmission mechanism connecting the drive motor to one of the shafts. In order to simplify installation and servicing of the pump, the shafts are mounted vertically. The side chamber, synchronization mechanism, and transmission mechanism are disposed below the lower rotor pair.

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 lubricating system for supplying oil to the bearings of a shaft having a central oil pumping passage open at one end. An oil delivery tube reaches into the oil pumping passage. To achieve a positive transfer of the oil from the oil delivery tube to the inner wall of the oil pumping passage, means are associated with the upper end of the oil delivery tube for bringing the oil onto the inner wall of the oil pumping passage.