A conveyor bearing is not load-limited, it is lubricant-limited: at 30 rpm the grease never forms a film, and dust is already inside. Conveyors & Bulk Handling duty is slow speed, abrasive dust and frame misalignment; the material is what decides whether the bearing survives it.
| Industry duty | slow rotation under steady belt pull, with abrasive dust at the load point |
|---|---|
| Typical media | abrasive dust, fines, washdown water |
| Housing temperature | −20 to +90 °C |
| Material and grade | through-hardened chrome steel — 100Cr6 / 52100 |
| Hardness | 59–65 HRC |
| Temperature ceiling | 120 °C (200 °C stabilised) |
| Corrosion / chemical | none — rusts without protection |
| Relative cost | 1.0× of a standard 52100 bearing |
Bulk handling is slow, dusty and continuous. Slow rotation means boundary lubrication, so the base oil in the grease is doing all the work; dust means the seal is the real bearing. A 52100 insert unit in a cast housing is cheap, self-aligning, and replaceable in minutes, which is why it dominates the industry despite the harsh duty.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Head pulley | Ball bearing unit | 52100 insert, cast iron housing, triple-lip seal | Self-aligning seat and a seal that keeps fines out. |
| Tail pulley | Ball bearing unit | 52100 insert, take-up housing | Take-up travel keeps belt tension without loading the bearing axially. |
| Snub / bend pulley | Deep groove ball | 52100, C3, 2RS | Small radial load, sealed for life. |
| Screw conveyor end | Self-aligning roller | 52100, 222xx, C3 | Misalignment from a welded trough plus shock from the flights. |
| Material | Fit here | Choose it when |
|---|---|---|
| 100Cr6 / 52100 | Best fit | Standard bulk handling where a cheap, replaceable unit is the design intent. |
| 440C | Workable alternative | Washdown food conveyors and fertiliser plant where the housing sees water. |
| Bronze | Workable alternative | Very slow, heavily loaded pulley shafts where a bush outlasts a rolling bearing. |
Because at that speed the rolling contact never builds a full film. The grease must supply the lubricant, and once it oxidises or dries, metal contact begins.
In dirty plant, yes, if someone actually greases it on schedule. A missed schedule is worse than a sealed unit.
Water ingress followed by dust. The resulting paste grinds the raceway and the seal lip in weeks.
Hardness, temperature, corrosion and equivalents for 52100 chrome steel.
Read →Typical duty, recommended types and suffixes for conveyors.
Read →Washdown food conveyors — food-grade conveyors cleaned with water and caustic every shift.
Read →Chemical & fertiliser — fertiliser, salt and chemical conveyors where chlorides are constant.
Read →Send the position, bore size, quantity and the medium it sees. We reply with the material certificate, clearance class, lubricant and price within 30 minutes on working days.