The Stockpile · Pile 03 — The Fix List
Carryback comes off in layers, and each layer takes a different blade in a different place. Here’s who does what — and how many positions you actually need.
No single blade gets a belt clean. Carryback — the material that sticks to the belt past discharge — comes off in layers: a heavy bulk layer, a thin pressed film under it, and a damp residue under that. Each layer takes a different blade, a different pressure, and a different spot on the conveyor, which is why belt cleaning grew into a system of positions: primary, secondary, tertiary. The positions are teammates, not upgrades — a secondary cleaner without a primary in front of it just drowns.
Where: on the face of the head pulley, just below the material trajectory, while centrifugal force is still helping throw material into the chute.
Blade: flexible elastomer (urethane), run at a positive rake — the blade peels rather than scrapes.
Job: the rough cut. A well-specified, well-tensioned primary takes the majority of the carryback — the heavy layer — and takes the abuse that comes with it: splice impacts, tramp material, the works.
Where: just past the head pulley, where the belt leaves the pulley face — against the pulley or backed by a hold-down roll so the belt cannot flutter away from the blade.
Blade: harder metals — tungsten carbide tips are the classic — run at a negative rake, scraping the thin film the primary left.
Job: precision. With the heavy layer gone, a secondary can run a finer edge at controlled pressure and take the system to the “doesn’t pile up under the conveyor anymore” level most plants are after.
Where: further along the return run, often with its own dribble chute or scavenger conveyor to carry what it removes back into the product flow.
Blade: whatever the residue demands — a third scraper, or a rotating brush cleaner, or a wash-box with spray and squeegee in plants with water available.
Job: the last few percent, for conveyors where the last few percent matters: enclosed galleries where any dribble accumulates, food and cement service, belts feeding sensitive equipment — and cleated or chevron belts, where brushes aren’t optional but the only tool that can follow the profile.
| Primary | Secondary | Tertiary | |
|---|---|---|---|
| Mounts | Head pulley face, below trajectory | Just past the pulley, belt supported | Down the return run, own dribble chute |
| Blade | Urethane, positive rake | Carbide-tipped or urethane, negative rake | Scraper, brush, or wash system |
| Removes | The heavy layer — the majority | The pressed film | Damp fines and the last traces |
| Personality | Tough, takes the abuse | Precise, needs protection | Specialist, needs a reason |
| Typical duty | Every serious conveyor | Most conveyors, all wet/sticky ones | Enclosed, sanitary, cleated, or critical belts |
Before adding a position, make the ones you have work: correct blade grade, correct tension, square to the belt, on a re-tension schedule. A neglected primary plus a new secondary equals two neglected cleaners. Our belt cleaners section has the troubleshooting table; we also run scheduled re-blade and re-tension routes so it stays fixed.
Rules of thumb, honestly stated as rules of thumb: a good primary takes the clear majority of the load, and a well-tensioned primary + secondary pair gets most plants to effectively clean — the level where piles stop forming under the return run. Exact numbers depend on material, moisture, belt condition and tension, which is why we measure by what accumulates, not by brochure percentages.
You can, and the secondary will briefly impress you and then wear out fast — a fine carbide edge doing bulk removal is the wrong tool at the wrong pressure. The primary exists to protect the secondary. Install them as a pair.
Run at correct tension and negative rake on a vulcanized belt, no — they clean for months without measurable cover wear. The damage stories come from over-tensioning and from carbide meeting proud mechanical fasteners. On mechanical splices, spec splice-friendly blades.
A little water ahead of the cleaners softens sticky films and can lift a system's performance noticeably — where freeze, product spec and housekeeping allow it. Wash-box tertiary systems formalize this. It is an option we spec case by case, not a default.
Tension checked monthly at minimum (weekly on hard duty), blades rotated or replaced on wear, and the whole system re-squared whenever the belt or splice changes. This is exactly the kind of route our crews run on schedule so it actually happens.
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