A pump mechanism having multiple cylinders, whose axes are situated around a crankshaft to enclose predetermined angles, and whose pistons are each functionally connected to a connecting rod mounted on a crank on the crankshaft, each connecting rod being mounted on its own crank and the cranks having a predetermined angular offset to one another. This angular offset of the cranks is selected in accordance with the angle which the cylinder axes enclose in such a way that the phase shifts between each two pistons of the cylinders actuated in sequence during a rotation of the crankshaft are equally large.