Abstract: A vacuum pump includes an evacuation chamber, a gear chamber, a partition separating the evacuation chamber from the gear chamber, a rotary pump shaft extending through the partition and having one end connected to a vane arranged for rotation in the evacuation chamber and having another, opposite end extending into the gear chamber, a shaft bearing surrounding the pump shaft and received in the partition, a labyrinth seal surrounding the pump shaft and received in the partition for sealing the evacuation chamber from the gear chamber, an oil sump defined in the gear chamber for accommodating oil therein, an evacuation device for generating a vacuum in the gear chamber and an oil loss preventing arrangement for avoiding an oil deficiency in the gear chamber due to the vacuum generated therein.