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Conveyor Return Idler Roller
Precision sealed steel return idler rollers supporting the unloaded belt run on WMM collection and feeder conveyors.
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At a glance
| Shell OD | 89 mm or 108 mm |
|---|---|
| Shell wall thickness | 4–5 mm, cold-drawn steel |
| Shaft diameter | 20 mm or 25 mm (size-dependent) |
| Bearing type | 6205-2RS or 6206-2RS, C3 clearance, sealed for life |
| Shell material | Cold-drawn steel, enamel paint finish |
| Face length | 670–1,350 mm (to suit belt width with 10 mm per-side overhang) |
| Belt widths covered | 600–1,200 mm |
| Max radial load capacity | 2.5–4.5 kN (size-dependent) |
Overview
Return idler rollers are mounted along the underside of every conveyor in the AVL-WMM feed system, supporting the empty belt as it travels from the head pulley back to the tail pulley. Although the return run carries no material load, the rollers must support the belt weight continuously and resist contamination from wet aggregate fines carried back on the belt underside. On a 20 m collection conveyor, return idlers are typically spaced at 2.5–3.0 m intervals, giving six to eight rollers per conveyor run.
Return idlers are a consumable item that is often overlooked until failure, at which point a seized or fragmented roller drags against the belt underside, cuts the bottom cover, and can derail the belt — a costly unplanned shutdown that interrupts production and may require belt replacement.
Function
Return idlers maintain belt flatness and prevent sag on the return run. They must spin freely with minimal drag to avoid differential belt wear; a rule of thumb is that return idler rolling resistance should not exceed 1.5% of net belt tension. Seized return idlers increase drive motor load and reduce the tension available for the loaded carrying side. In WMM plants where aggregate carryback is not fully removed by the head scraper, idlers accumulate eccentric material build-up, causing belt bounce and tracking deviations that propagate to the weigher span.
Construction & quality
Shell: seamless cold-drawn steel tube, 89 mm or 108 mm OD, wall thickness 4–5 mm, painted for corrosion protection. Shaft: solid C45 steel ground to h6 tolerance for precision bearing inner race fit. Bearings: deep-groove ball bearings (6205-2RS or 6206-2RS), Grade C3 clearance, contact-sealed (2RS) with an additional non-contact labyrinth slinger on the inboard face. End caps: pressed steel or glass-filled nylon, snap-retained with positive lock. Shaft ends: flats or circlip grooves to CEMA standard for drop-in frame mounting. Bearings are greased for life; no field re-greasing provision is required.
When to replace
- Audible roughness, grinding, or intermittent squealing at one roller on the return run
- Visible flat spot or eccentric material build-up causing rhythmic belt bounce
- Roller failing to rotate freely under a hand spin test when stationary
- Corrosion perforating the shell surface visible through the paint coating
- End cap dislodged, exposing bearing to water and aggregate contamination
Compatibility & fitment
Face lengths available for all belt widths from 600 to 1,200 mm across the AVL-WMM conveyor range; shaft-end detail — flat, groove, or hexagonal — is matched to the plant's return-idler frame standard.
Why buy from Avelta
Avelta return idlers are manufactured to CEMA Class C or equivalent dimensional standards, with bearing grades selected specifically for the wet and dusty return-run environment of WMM aggregate plants.
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