Conveyor Idlers & Belt Tracking | A&K Machine & Fabrication

Why A&K for Idlers

The Foundation of Every Belt Conveyor

Idlers do the unglamorous, high-mileage work of every belt conveyor: supporting the belt, supporting the load, keeping the system tracking straight, and absorbing impact at load points. When they wear or fail, the belt drifts, the edges fray, the carry-back accelerates — and you're shutting the line down sooner than you planned.

A&K machines complete idler assemblies and replacement rollers to your conveyor's exact spec. We work from your sample, your OEM number, your gearbox or frame dimensions, or your CAD drawings. Standard and non-standard configurations both run through the same shop.

All CEMA 502 troughing angles: 20°, 35°, 45° (3-roll), plus 5-roll picking sets

CEMA Classes B, C, D, E, F — bearing and shaft sized to your tonnage

Standard roll diameters: 4", 5", 6", 7" — special diameters cut on request

Sealed cartridge or greaseable taper-roller bearing options

Triple-labyrinth or taconite seals for dust- and water-heavy service

Carbon steel, hot-dip galvanized, or 304/316 stainless shells

Reverse-engineered drop-in replacements when the OEM is gone

Bulk-rate pricing on production runs; no minimum on one-offs

Black-coated finned conveyor roller with brass contact bands — custom-machined idler by A&K Machine & Fabrication, Jacksonville FL

Idler Types

Every Position on the Belt

From the head pulley to the tail pulley, every section of a conveyor needs the right idler for its role. A&K machines all of them.

Carrying Idlers

Support the loaded belt on the carrying run. Flat single-roll, two-roll V, three-roll troughed (20°/35°/45° per CEMA 502), and five-roll picking sets for wide belts. Roll diameters 4"–7"; sealed cartridge or greaseable taper-roller bearings.

Return Idlers

Support the empty belt on the return run. Flat single-roll, two-roll V-return (10°), and self-cleaning rubber-disc / spiral return configurations — pick rubber-disc or spiral when carry-back is hammering your return strand and grinding into the roll face.

Belt Training Idlers

Self-aligning trainers for carrying and return strands. Pivot-frame designs with steering rollers sense belt drift and angle the trough to correct it before edge damage or spillage. Essential on long-center conveyors where small misalignments compound over hundreds of feet.

Impact Idlers

Rubber-cushioned rolls positioned under load points to absorb the energy of material drop. Standard rubber-disc impact rolls or solid impact bars handle the bulk of installs; protects the belt from punctures and reduces vibration through the structure. Spaced 6"–12" centerline under high-impact transfer chutes.

Transition Idlers

Gradient-angle idlers (typically half the trough angle, then full) for the zones near head and tail pulleys where a troughed belt has to flatten out. CEMA recommends a minimum transition distance of ~2× belt width on standard troughs to keep edge tension within limits.

Heavy-Duty & Specialty

CEMA Class E / F rolls for high-tonnage aggregate, finned rolls for wet/sticky material, ceramic-faced rolls for highly abrasive applications, and stainless rolls for washdown and chemical service. Built-to-print solutions when standard catalog parts won't survive your environment.

Row of finished bronze conveyor rollers with grooved profiles in a shipping case — A&K Machine & Fabrication, Jacksonville FL

Materials & Bearing Specs

Built for Your Environment

Idler service life is mostly about matching the material and bearing to the environment. The wrong combination wears out in weeks; the right one runs for years. CEMA standard 502 sets out six load classes — A through F — and we spec the bearing, shaft, and seal to land you with the L10 life you actually need.

CEMA Class B / C: Light-to-medium duty (18"–48" belts, lower tonnage). Standard sealed cartridge bearings, 60,000-hour L10 design target.
CEMA Class D / E: Heavy duty for aggregate, mining, and high-tonnage bulk (30"–72" belts). Larger shaft, deep-groove or taper-roller bearings.
CEMA Class F: Extra-heavy duty (60"+ belts, severe impact zones). Heaviest shaft and bearing; 30,000–60,000-hour L10 in worst-case material.
Sealed cartridge bearings: Pre-lubed sealed-for-life. Pick when access for greasing is impractical and the environment is moderate.
Greaseable taper-roller: Re-lubricable, higher load capacity. Required for Class E / F service and recommended where contamination is constant.
Triple-labyrinth seals: Standard for outdoor and indoor dust service. Multiple non-contact labyrinth rings shed water and fines without parasitic drag.
Taconite seals: Purgeable grease-packed seal package for mining and aggregate plants — sand, dust, washdown, water sprays. Re-grease at scheduled intervals.
Shell materials: Carbon steel (default), hot-dip galvanized (wet/outdoor), 304/316 stainless (food, chemical, washdown), HDPE/UHMW (lightweight, chemical, food-grade).

Spacing & Tracking

Get the Spacing Right, Tracking Follows

Most "belt tracking problems" actually start at the idler spacing — too far apart and the belt sags between sets, scrubs the edges, and drifts. Too tight and you're paying for steel that isn't earning its keep. CEMA gives clean rules of thumb:

Carrying idler spacing: 3 ft to 5 ft on standard troughed belts. Tighter under load points (typically half spacing). Drives allowable belt sag — a 2% sag limit is the industry default for bulk handling.
Return idler spacing: 10 ft is typical for the return strand — the belt's empty, so it can span further. Increase to 5–6 ft if the return belt is fouled by carry-back.
Impact idler spacing: 6"–12" centerline directly under transfer chutes and load skirts. Continues for 3–5 ft past the load point.
Transition zone: Minimum 2× belt width between the last full-trough set and the head/tail pulley centerline. Use half-trough transition rolls to bridge the angle change.
Training idler placement: One on the carrying side every 100–150 ft and at the tail end of the carrying run; one on the return side mid-span. More on long-center conveyors.

Belt drifting? Walk it like this before you call in a tracking-roll swap:

Check that the conveyor frame is square and level — most "tracking" problems are structural

Make sure no idler set is cocked — a single rolled-back idler will steer the belt

Inspect the head and tail pulley crowns — wear flat = tracking dies

Verify the load is centered on the belt — off-center loading pulls the belt to the heavy side

Check return-side carry-back buildup on idlers — caked fines unbalance the roll

Confirm the belt splice is square (perpendicular to belt edge to ±1/8")

Verify take-up tension; a slack belt won't track no matter how good the idlers are

If you've cleared all of those and the belt still drifts, that's when training idlers earn their keep. We supply pivot-frame trainers (Hyde-style, Flexco-pattern, or built to your OEM print) for both carrying and return.

Quote-Ready Spec

What to Send Us for a Drop-In Replacement

If you can give us the spec below, we can usually quote within a business day and machine a drop-in replacement within a week. If you're missing pieces, we work from a worn sample on a granite plate — we just need it shipped or dropped off.

Belt width (in inches): 18, 24, 30, 36, 42, 48, 60, 72…

Troughing angle: 20°, 35°, 45°, flat, V-return, 5-roll picking

Roll diameter (4", 5", 6", 7") and roll length (face length, not overall)

Shaft diameter and shaft end style (square, hex, round-with-flat, CEMA)

Frame-bolt pattern and centerline-to-centerline mounting dimension

Material: aggregate, coal, ore, wood chips, food, recyclables (drives shell & seal choice)

Environment: indoor dry, outdoor wet, washdown, dusty, washout, corrosive

Belt speed (ft/min) and approximate tons-per-hour throughput

Service interval — how often you can re-grease, or whether sealed is required

Production run of finished idler rolls with bearing seats and shaft ends — A&K Machine & Fabrication, Jacksonville FL

Our Process

From Worn Sample to New Idler on Your Dock

Spec & Quote

Send us a worn idler, the OEM tag, or the frame dimensions. We measure on a granite plate, identify wear modes, and come back with a fixed quote and a real lead time.

Material & Bearings

We recommend the material and bearing combination based on your environment — not just "what the OEM used." If wear has been heavier than expected, we upgrade the spec for the next cycle.

Machine & Assemble

CNC-turned shells, machined end caps, pressed-in bearings, balanced rolls. Every assembly is inspected against the print before it leaves the machine.

Ship or Install

Palletized for pickup or drop-shipped to your site. For customers in our service area, our on-site crew can swap them in during your scheduled outage.

Industries

Who We Supply Idlers To

Mining & Aggregates Agriculture Food & Beverage Wood, Pulp & Paper Recycling Distribution & Warehouse Airports Marine Power & Utilities Wastewater Pharmaceuticals Construction & Roads

Common Questions

Idler FAQ

Can A&K match an OEM idler that's been discontinued?

Yes — this is one of the most common reasons customers call us. Send the worn idler (or just a photo + the frame spacing), and we'll reverse-engineer a drop-in replacement. The bearing bore, shaft diameter, length, and frame-bolt pattern all come out matching the original.

What troughing angles can you make?

Per CEMA 502, 20°, 35°, and 45° are the standard three-roll troughing angles. We also build flat (0°), two-roll V-trough, and five-roll picking idler sets for wider belts and deep-trough service. The angle drives load-carrying capacity for a given belt width — a 45° trough on a 36" belt carries roughly 1.5× the volume of a 20° trough at the same speed. Send us belt width, bulk density, and tph and we'll recommend the right angle.

How do I know which CEMA Class to spec?

CEMA 502 divides idlers into Classes A through F by belt width, roll diameter, and shaft size. Rough rule: light packaging service is Class B, general industrial is C, mining/aggregate is D or E, and severe-duty (taconite, ore, primary crusher discharge) is F. The class governs bearing size, shaft diameter, and L10 life target (typically 60,000 hours for B–C, 30,000 for D–E severe). If you tell us belt width, material, and tph, we map it to the right class — and if your existing idlers are wearing fast, we'll bump you up a class on the replacement.

Sealed-for-life or greaseable bearings — which do I want?

Sealed cartridge bearings are factory-packed and never re-lubed. They're the right call when access for routine greasing is impractical (overhead conveyors, return strands buried in the structure) and the environment is moderate. Greaseable taper-roller bearings carry higher loads, run cooler under heavy service, and let you flush contamination out — required for Class E/F duty and recommended where dust or water is constant. Triple-labyrinth or taconite seals add another layer of contamination defense on either type.

My belt won't track — is it the idlers?

Probably not, at least not directly. Tracking problems usually trace to a structural issue (out-of-square frame, cocked idler), an off-center load (chute misalignment), a worn pulley crown, a non-square belt splice, or just under-tension. Walk those first — see our troubleshooting checklist above. If you've cleared all of those and the belt still drifts, training idlers are the right next move. We supply pivot-frame trainers on both carrying and return strands.

How do I tell if my idlers are worn out?

Three signs: roll surface grooved or out-of-round (run your hand along it — a smooth roll is healthy); audible bearing noise when the line is running; or hot housings to the touch. Any one of those means the idler is past service life and the belt is paying for it in extra wear.

What's the lead time on a standard replacement idler?

Most standard idlers ship within a few business days when material's in stock. We prioritize emergency breakdown work — call 904-388-7772 with your specs and we'll tell you straight whether we can hit your deadline before you commit.

Can A&K install idlers on-site, or only supply them?

Both. For customers in our service area, our on-site crew can swap idlers during your scheduled maintenance window — measured, installed, belt re-tracked, and tested before we leave.

Other Conveyor Components

Working Up & Down the Belt

Pulleys & Accessories

Head, tail, snub, and bend pulleys with crowned faces and your choice of lagging — bare steel, rubber, ceramic, or polyurethane.

Explore Pulleys

Pillow Blocks & Bearing Housings

2-bolt and 4-bolt pillow blocks, take-up units, and flange-mount housings for the bearing on every idler, pulley, and shaft.

Explore Bearings

All Conveyor Components

Back to the full conveyor parts overview — gearbox shafts, scrapers, sprockets, take-ups, auger flighting, and more.

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Start Your Project

Send us your details — drawings, dimensions, or just a description. We'll get back to you within 48 hours on most quotes. For faster response or lead time questions on jobs, just call.

Fast Response

We respond to most quote requests within 48 hours. For faster responses or lead time questions on specific jobs, call us directly at 904-388-7772.

We Ship Anywhere

Based in Jacksonville, FL — we ship finished parts and components throughout Florida, the Southeast, and beyond.

Prefer to Call?

Reach us at 904-388-7772, Mon–Fri 7:00 AM – 3:30 PM (closed Sat–Sun).

Roll the Belt. Track the Load. Stay Aligned.