A pump, particularly a vane pump or roller cell pump, whereby the vane pump or roller cell pump is provided with a two-stroke contour ring, with a rotor, inside of which vanes or rollers are mounted in a manner that enables them to be radially displaced, with at least one side side plate, which seals the rotating group, with a casing and with a casing cover, whereby the rotor is driven by a shaft and the shaft is mounted inside the casing and, optionally, inside the cover.