Peripheral pump

A peripheral pump having a driven rotor (2), which rotates in a pump casing (1) and in which a ring (5) of blades (6) is formed in each of its end sides (3, 4) for the purpose of delivering a liquid from an inlet duct (18) to an outlet duct (19), and having annular ducts (8, 9) having semicircular cross sections, which are formed in the pump casing (1) on both sides in the region of the blades (6) and, together with blade chambers (10, 10a) between the blades (6), form delivery chambers (11, 12) which face one another, the rotor (2), in its radially inner region and in the region of its circumferential edge, facing toward the pump casing (1) at a distance therefrom so as to delimit a sealing gap (14), and the blades (6), as seen in the direction of rotation, rising from the central region of the rotor toward the end sides (3, 4), wherein, in the region of two mutually facing blade chambers (10, 10a) of the blades (6) a communicating passage (13) is formed for the liquid to flow over, the inlet duct (18) being connected to one delivery chamber (11) and the outlet duct (19) being connected to the other delivery chamber (12), wherein the delivery chambers (11, 12) have a semicircular cross section in the region of the blade chambers (10, 10a), and wherein the communicating passage (13) has a contour defined by an overlap of the circular cross sections of the delivery chambers (11, 12).