Escalator having step treads that interengage in the return run

The invention relates to an escalator (1), which is constructed in a space-saving manner and can be operated with little wear. The escalator (1) has a plurality of step treads (3) and a guide rail arrangement (55) for guiding the step treads (3), in particular during a return run. Each step tread (3) has a front toothing structure (33) on a forwardly directed end face (31) and a rear toothing structure (41) on a rearwardly directed region (39) of a seating face (25), the front and the rear toothing structures (33, 41) being formed so as to be complimentary to each other, such that the front and the rear toothing structures can interengage in the forward run. The escalator is characterized in that, by means of a specific configuration of the guide rail arrangement (55), at least also in the central region (11) of the return run, running at an angle, the toothing structures (33, 41) of adjacent step treads (3) are arranged to interengage. As a result, dimensions of the escalator can be reduced, and adjacent step treads (3) guide one another as a result of the interengagement, by which means wear phenomena are reduced. The interengagement of adjacent step treads (3) in the return run can be enabled, for example, by the step treads being deliberately tilted with respect to one another with the aid of the guide rail arrangement (55) as the step treads travel, in order then to approach one another horizontally.