Every hub unit on the road started as a 52100 raceway, and the specification work is in the seals and the clearance rather than the steel. Automotive & Electric Vehicles duty is shock load, wide temperature swings and electrical erosion from the inverter; the material is what decides whether the bearing survives it.
| Industry duty | shock at the wheel end, 15,000 rpm in the e-drive, and inverter shaft voltages |
|---|---|
| Typical media | road spray, brake dust, gear oil, glycol |
| Housing temperature | −40 to +150 °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 |
Automotive bearings are bought in millions, so the grade is settled: through-hardened or case-carburised chrome steel, with an inclusion content controlled far more tightly than a general engineering 52100. The bearing is designed as a unit with its seal, its grease and its sensor ring, and the service life is set by the grease and the seal. On an EV the one new variable is the inverter voltage, which turns the bearing into part of a circuit.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Wheel hub, non-driven | Deep groove ball | 52100 hub unit, 2RS, sealed for life | Generations of hub units are built around 52100 races. |
| Wheel hub, driven | Tapered roller | 52100, matched pair, preset | Combined cornering and drive load; preset removes field adjustment. |
| Gearbox input | Cylindrical roller | 52100, NU/NJ, C3 | High radial load at 15,000 rpm; NU floats on the shaft. |
| E-drive rotor | Deep groove ball | 52100, C3, 2RS, or hybrid for voltage | Locates the rotor; shaft voltage is the EV-specific risk. |
| Material | Fit here | Choose it when |
|---|---|---|
| 100Cr6 / 52100 | Best fit | Volume positions where cost, capacity and a sealed-for-life design all point the same way. |
| Si3N4 | Workable alternative | E-drive positions with inverter-induced shaft voltage, or speed beyond the steel-ball limit. |
| 440C | Workable alternative | Brake-adjacent and road-spray positions where cosmetic rust becomes a warranty claim. |
52100 at 60 HRC is already at the practical limit for rolling contact. Harder grades are more brittle, and a hub sees kerb impact.
Water through the seal and grease degradation. The raceway usually shows rust or grease failure, not classical subsurface fatigue.
The hub is similar. The difference is at the motor and gearbox, where shaft voltage and higher speed change the material choice.
Hardness, temperature, corrosion and equivalents for 52100 chrome steel.
Read →Typical duty, recommended types and suffixes for automotive & ev.
Read →Brake & road-spray — brake-adjacent mechanisms, exposed chassis joints and sensor bearings.
Read →E-drive & high speed — e-drive rotor and gearbox positions where inverter voltage erodes the raceway.
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.