the invention relates to an eccentric screw pump with a annular outer part and an inner part arranged therein , the interior of the outer part and the exterior of the inner part tapering in a complementary manner towards an axial end . in the axial direction , the inner part and the outer part are movably received in relation to each other and the inner part and / or the outer part are configured in such a manner that pressure applied to the pressure side of the eccentric screw pump generates a force that acts upon the inner part axially to the direction in which the inner part tapers and / or a force that acts upon the outer part in an opposite axial direction .