The bearings, gears and seals of the pump are lubricated by the pump oil inside the motor
side cover and gear side cover. A series of oil seals stop the oil from reaching the rotor side
of the pump. Inside of the motor side cover and gear side cover is evacuated. You can check
the oil level by the oil level sight glass mounted on the motor side cover/gear side cover. The
motor side cover/gear side cover is equipped with a refilling screw plug and an oil drain
screw (see Fig.2).
1.2.3 Principle of operation
The motor shaft of the pump drives one of the rotors in the rotor housing through the
hydraulic drive inside the motor side cover. The synchronizing gears drive the second rotor
in the opposite direction inside the rotor housing. A small clearance is maintained between
the rotors and between the rotors and the inner wall of the rotor housing. This clearance
allows the pump to operate at high speed without mechanical wear and without the need for
lubrication inside the swept volume.
1.2.4 Hydraulic drive
The hydraulic drive consists of a fluid coupling which connects the motor shaft to the rotor.
The system configuration ensures that the rotor's rotational speed is reduced, when the gas
load is too high. When the gas load is reduced, the rotors accelerate to full speed. This allows
the pump to operate continuously over the vacuum range without the risk of motor overload
and without the need for bypass valves and associated pipelines.
The fluid coupling is extremely sensitive to the viscosity of the pump oil. The packaged
pump is equipped with special oil for the BAOSI vacuum pump.
