low pressure accumulation on this relatively simple system the belt is pressed against the rollers with spring-loaded pressure devices. if the carried goods are accumulated , e.g. by means of a mechanical accumulation device, the rollers in question are blocked while the belt continues to run. the belt surface touching the carrying rollers must be formed so that it can slip with minimum resistance on the blocked rollers, but at the same time continue to drive the other carrying rollers reliably. on the driving pulley surface , the belt must have a high coefficient of friction (preferably nitrile rubber)