The pumps are valve-controlled, self-priming radial piston pumps with fixed displacement. They consist essentially of the housing, eccentric shaft and 3, 5 or 10 pump elements, with suction valve, pressure valve and piston. The pistons are arranged radially to the eccentric shaft. The hollow piston with the suction valve is guided in a cylinder and pressed onto the eccentric by the spring. The radius of the piston running surface corresponds to the eccentric radius. The cylinder provides sealing against a hemispherical element.