The oil-free piston vacuum pumps of the range KV are realized where utmost operating safety is required, as for example in 24/7-application in industry enterprises, for retention of hydraulic oils on service at construction machinery. The oil-free piston-vacuum pumps offer as a 2-phase pump a vacuum of up to 30 mbar. The characteristic of the oil-free piston-vacuum pumps are the integrated, overdimensioned bearings. Owing to this, the best possible lifetime and reliability of the vacuum pumps is achieved. The suction capacity of oil-free piston-vacuum pumps of the range KV remains almost unchanged even after many thousand operating hours because of the exactly aligned components.