Full definition
Return idlers are crucial components in the design and operation of conveyor systems, specifically serving to support the return strand of the conveyor belt as it travels back from the discharge end to the loading end. These idlers are essential for maintaining the belt's alignment and reducing wear on the belt's underside. A well-designed return idler system can significantly enhance the efficiency and longevity of a conveyor system. Typically, return idlers are larger in diameter compared to carrying idlers, which helps reduce the rotating resistance encountered by the belt on the dirty side. This is particularly important as the return section of the belt is not carrying any material load, allowing for wider spacing of 2-3 meters between the idlers, which can help minimize the resistance and potential for misalignment due to material buildup.
There are several types of return idlers tailored for specific applications. The plain flat return idler is the standard design, often made from steel or HDPE, which provides a smooth surface for the belt to run against. V-return idlers utilize two angled rollers to keep the belt centered, mitigating the risk of lateral shifting, which is common in wide belts. Self-cleaning or spiral return idlers feature helical rubber discs that effectively shed any material adhering to the belt's underside, while rubber-disc idlers use spaced rubber rings to further minimize the contact area with the belt, thus reducing the potential for material build-up.
The primary challenge associated with return idlers is material carryback, which occurs when material adheres to the belt's underside. This carryback can accumulate on the return idlers, leading to belt mistracking and potential idler seizure. Effective belt cleaners at the head drum are crucial in minimizing the amount of carryback that reaches the return strand, thereby ensuring a smoother operation. Additionally, the seal quality of return idlers is critical, as they are often exposed to material fines, water, and slurry, which can compromise their functionality and lifespan. Compliance with standards such as CEMA and DIN 22112 is essential for ensuring the reliability and performance of return idlers in various applications.