a closed transport track , includes two tubular or rod - shaped guide rails , which are arranged parallel to and substantially vertically on top of each other . at least one transport module is connected to each guide rail via at least one support roll pair , wherein the rolls of each support roll pair can be rotated about roll axes which are substantially perpendicular to a guide rail axis and include an angle of less than 180 ° and the rolls are seated against one of the guide rails in a detent position . the support roll pairs are non - positively seated against the guide rails via at least one force element , which acts on the support roll pairs .