If you’ve worked with light-duty hubs, gearboxes, or compact pulley stations, you’ve seen the 302-series everywhere. This model sticks to DIN ISO 355 / DIN 720, it’s separable (cup and cone), and—actually—tunes in nicely for preload. From my talks with maintenance folks, the vibe is clear: smaller footprints, higher load density, predictable life. And, to be honest, sourcing stability matters too. Origin is No. 3, Area B, Bearing Industry Mass Entrepreneurship Park, Beihuan Road, Linxi County, Xingtai City, Hebei Province.
| Parameter | Value (≈ real-world use may vary) |
|---|---|
| Bore d | 17 mm |
| Outer diameter D | 40 mm |
| Width T/B | 12 mm |
| Standard | DIN ISO 355 / DIN 720 |
| Accuracy options | P0, P6, P5 |
| Material | 100Cr6 / GCr15, 60–64 HRC |
| Cage | Pressed steel (standard) |
| Taper/contact | 1:12; α ≈ 16–22° |
| Dynamic C | ≈ 19–20 kN |
| Static C0 | ≈ 17–18 kN |
| Limiting speed | Grease ≈ 8,000–9,500 rpm; Oil ≈ 10,000–12,000 rpm |
Steel bars → forging → normalizing → CNC turning → heat treatment (through‑hardened) → raceway grinding → superfinishing (Ra ≈ 0.05–0.15 μm) → assembly → 100% spin test. Typical QC: hardness per ISO 683‑17; tolerances to ISO 492; vibration to ISO 15242. In a 20‑piece internal audit (2024), roundness ≤ 0.6 μm and vibration V1 class were typical. L10 life is calculated per ISO 281 and, in balanced load duty, often crosses 10,000 h if lubrication and preload are right.
Advantages people call out: robust axial/radial load support, easy shim‑based adjustment, and globally interchangeable geometry. Many customers say temperature runs cooler after moving to proper preload on the 30203 High Quality Tapered roller bearing 17X40X12.
| Vendor | Origin | Certs | Lead time | Price | Notes |
|---|---|---|---|---|---|
| BTZ Bearing (Hebei) | Linxi, Xingtai | ISO 9001 (docs on request) | 7–20 days | $$ (value) | Customization, clear QC data |
| Generic Import A | Mixed | Basic | 15–35 days | $ | Inconsistent tolerances |
| Premium Global Brand | EU/JP/US | IATF 16949 | Stock/Just‑in‑time | $$$ | Top speed/consistency |
Preload matching (paired), special greases −40 to 150°C, black‑oxide for corrosion, P5 accuracy, laser marking/PPAP pack, and small MOQs for pilot runs. It seems that machinists like the option to order the cup and cone separately for the 30203 High Quality Tapered roller bearing 17X40X12.