Full definition
A cylindrical roller that supports the conveyor belt and its material load on the upper (carrying) strand of the conveyor. Idlers are the most numerous component in a conveyor system and their performance directly affects belt life, energy consumption, and maintenance costs. Standard diameters: 63, 89, 102, 108, 127, 133, 152, 159, 178, 194, and 219 mm. Roller length: matched to belt width plus clearance. Shell material: ERW steel tube (standard), HDPE (lightweight, corrosion-resistant, quiet), composite, or stainless steel (food/chemical). Bearings: 6204-6310 deep groove ball bearings, sealed/shielded, grease-lubricated. CEMA idler classes: B (30,000-hour L10 bearing life), C (60,000), D (60,000+, heavier loads), E (60,000+, extreme). Spacing: 0.8-1.5 m on carrying strand, reduced to 0.3-0.5 m in the impact zone. Idler drag (rotating resistance) directly affects belt tension and energy consumption — low-friction bearings and seals save significant power on long conveyors. Per CEMA 502 and DIN 22112.