Full definition
An idler roller supporting the conveyor belt on its lower (return) strand as it travels back from the discharge (head) end to the loading (tail) end. Return idlers are typically: flat (single roller, belt runs on the smooth back side), larger diameter than carrying idlers (to reduce rotating resistance on the dirty belt side), and spaced at 2-3 m intervals (wider than carrying side because the belt carries no material load). Types: (1) Plain flat — standard steel or HDPE cylinder. (2) V-return — two angled rollers in a V configuration to center the belt. (3) Self-cleaning/spiral — helical rubber discs that shed material sticking to the belt back side. (4) Rubber-disc — spaced rubber rings that reduce contact area with dirty belt. Material carryback adhering to the belt underside is the main challenge: it builds up on return idlers, causing belt mistracking and idler seizure. Belt cleaners at the head drum minimize carryback reaching the return strand. Per CEMA and DIN 22112. Seal quality is critical — return idlers are exposed to material fines, water, and slurry.