Abstract: A rolling mechanism encompassing various sets of Rollo-flex assemblies, as defined in the specification, within a customer supplied track, inside a retractable truck tarpaulin system and rolling and sliding doors. The invention improves on single roller and wheels presently used in retractable tarp system and rolling doors, particularly in moving vehicles by providing substantial savings over current systems, ensuring longer service life, providing a stronger and more stable covering system while protecting the wheels and rollers from the shock loads of road travel.