Conveyor idlers are rolling components used for supporting transmission belting on powered trough conveying systems for moving bulk materials such as coal, iron ore, aggregates, grains and loose materials which are used in industry sectors such as mining, quarry, agricultural, food, pulp and paper, chemical, and allied industries. Idlers generally consist of an outer tube which rolls underneath the transmission belting as well as a centrally mounted shaft for supporting the bearings, bearing seals and end caps. The outer tube is typically manufactured from steel pipe or composite tube, the shaft is manufactured from a range of steel grades and the bearings/seal assembly is dependent on environmental and design factors.

Conveyor idlers are procured for either manufacturing new bulk handling conveyors or as replacement components for repairs and maintenance of existing systems, process plants or overland conveyors. Herein, we will refer to trough idlers for the ‘light to medium’ capacity and belt speed systems, since components for overland, high speed and harsh terrain necessitate exacting design and sourcing of heavy-duty rolls and seals which in most instances require special batch runs and extended lead times.

When determining the correct component selection for trough belt conveyors, generally the idler dimension and frame widths are based on important factors such as the bulk density, belt speed, tonnage, conveyor length, belt width, environmental factors and system duty.

Idler rollers and components are available in many types, some being:

• Flat steel idlers for trough roller sets and carry return rolls.
• Composite idlers for reduced weight, energy savings and harsh environments.
• Impact idlers, Impact beds and Catenary idler sections for load and transition areas.
• Offset, In line, Transitional and Retractable conveyor frames
• Custom conveyor components, Roller conveyor units and Energy efficient idlers.

Component Procurement and Inherent Risk:

In recent years conveyor idlers were sourced predominantly from Australian manufacturers from a select few industry stalwarts, while imported rivals were unheard of. These local manufacturers built a reputation of quality units that have been proven over time as a reliable trough roller and equipped with an abundance of technical data. Today, the local marketplace has changed, and to the detriment of local manufacturers we are witnessing a diminishing supply of Australian built idlers as a direct result of conglomerates flooding the market with ‘low value’ imported generics. Although initial savings are attractive twofold compared to local rolls, consumers should consider the inherent risk associated and expect reduced idler longevity and limited technical data that is mostly unsubstantiated. Rule of thumb…when trough conveyors operate in harsh environments, high duty cycles, capacity and speeds, then it is advisable to procure idlers from reputable sources.

Idler Availability:

Trough conveyor idlers and components can be sourced through various outlets which advertise a broad range of roll sizes and frame dimensions. Unfortunately most advertised models now attract long lead times with only a handful of common belt widths and capacities available. Due to localised manufacturers de-stocking and importation of a select few models, research suggests that only two particular tube diameter size categories are readily available, these being 114mm and 127mm idlers predominantly to suit trough angle of 35-degrees and the lesser demand for 20-degree frames. Unless orders are preempted, stocking levels will only support a series of belt widths ranging between 450mm and 1200mm, with all other sizes available at extended lead times.