Abstract: An elongated frame retains a pair of drums, sheaves, pulleys or the like, at the ends of the frame, one of which is preferably power driven; the movable surface includes a plurality of step elements which have a flat top surface, preferably covered with a resilient surfacing, such as foam rubber, carpeting, or the like, to form an endless flexible belt which may be a composite of an endless belting to which slats are secured. The slat elements span the width of the apparatus and, in cross section, preferably have T-shape. A series of back-up support rollers with lateral guide flanges are located beneath the upper run of the movable support surface, with at least one elastic cushion support between the rollers and the slats, for example formed of an endless rubber V-belt in contact with the lateral flanges of the support rollers to accept lateral forces arising in use.