Belt Conveyor Idlers

Belt Conveyor Idlers

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Belt Conveyor Idlers

Belt conveyor idlers are crucial components that support both the carrying and return sections of a conveyor belt. Precisely crafted and securely installed idlers are essential for the effective operation of the belt conveyor system. The key functions of these idlers include providing adequate support and protection for the conveyor belt as well as supporting the loads being transported.

For handling bulk materials, belt conveyor idlers are specifically engineered with rollers of various diameters, each designed with antifriction bearings and seals on shafts. The frictional resistance of the idler rolls plays a significant role in influencing the tension of the belt, which in turn affects the amount of power required for operation. The frictional resistance is largely determined by the roll diameter, bearing design, and seal specifications, which are critical factors in idler performance.

Choosing the correct diameter of the roll, along with the appropriate size of bearings and shafts, depends on various aspects including the nature of the service, the load being transported, the speed of the belt, and the specific operating conditions. The designs of roller mounts on antifriction bearings reflect this selection process and can vary according to the application.

Fig 1 Different designs of roller mountings on antifriction bearings

Idlers are predominantly manufactured using steel tubes, which are consistently machined to ensure uniformity across the outer diameter as well as at both ends of the inner diameter. These tubes are fitted with antifriction bearings that rotate over a fixed steel spindle, ensuring smooth operation. The spindle ends are precisely machined to standard dimensions, aiding in quick installation within idler structures. Heavy-duty idlers made from robust steel tubes are utilized in high-stress areas such as material loading sections, while cast iron is preferred for corrosive applications, such as those involving coke handling.

Each belt conveyor idler manufacturer employs distinct antifriction bearing and seal arrangements to enhance durability and performance. The seals are fundamental in protecting the bearings from contaminants such as dirt and moisture while retaining the lubricant needed for smooth operation. Such thoughtful engineering reflects the expertise and innovation within the idler manufacturing industry, ensuring that idlers remain reliable over time.

Idler classifications

The idlers used in belt conveyors are broadly categorized into two main types: (i) straight carrying idlers and return idlers, which support the active side of flat belt conveyors and the return belt in both flat and troughed belt configurations; and (ii) troughing idler sets comprising two, three, or five rollers arranged to form a trough shape to support the belt in troughed systems. Carrying idlers accommodate the loaded section of the conveyor belt, whereas return idlers support the empty section.

The length of either straight or troughed idler sets is determined by the belt width and the desired clearance between the roller edges and the belt's edge. These idler configurations play an integral role in maintaining the integrity and efficiency of the conveying process.

Fig 2 Some types of conveyor belt idlers

Carrying idlers generally come in two configurations. One is designed for troughed belts and usually features three rolls with the outer rolls inclined upward while the center roll remains horizontal. The other configuration is meant for flat belts, consisting of a single horizontal roll mounted between brackets fixed to the conveyor frame.

For return idlers, the design typically consists of horizontal rolls positioned between brackets attached to the underside of the support structure that carries the carrying idlers. Two-roll ‘Vee’ return idlers are also employed to enhance belt training and increase load ratings.