Tapered roller bearings types
Tapered roller bearings are manufactured in bore diameters from 15 mm / 0.591 in to over 1 500 mm / 59.06 in, and their internal geometry is based on cones whose generatrices converge at a common point on the bearing axis. This configuration allows pure rolling motion without sliding in the contact zone, and enables absorption of combined radial and axial loads. The rolling elements are truncated conical rollers, stabilized by a rib on the inner ring that prevents their expulsion (“pumpkin seed effect”). The outer race (cup) and the inner assembly (cone) are separable, facilitating mounting and adjustment of internal clearance or preload.
Types and designations according to ISO 355
Section titled “Types and designations according to ISO 355”ISO 355 defines 126 dimensional series for metric tapered roller bearings, represented by an alphanumeric code indicating the contact angle, width, and outside diameter.
- Contact angle series: 2 (10° to 17°), 3 (17° to 24°), 4 (24° to 30°), 5 (≥ 30° with high thrust).
- Width series: 0 (narrow), 1 (normal), 2 (wide).
- Diameter series: 0 (light), 2 (medium), 3 (heavy). Bearings are grouped into families according to load capacity and speed limit. The following table shows the most common dimensional series with their inch equivalent.
| ISO 355 designation | Traditional series | Code example | Typical contact angle |
|---|---|---|---|
| 2FB | Light standard angle series (e.g., 302) | 30206 | 12° – 16° |
| 3FB | Medium standard angle series (e.g., 322) | 32210 | 14° – 18° |
| 3FC | Medium steep angle series (e.g., 303) | 30308 | 28° – 32° |
| 4FE | Heavy medium angle series (e.g., 323) | 32312 | 20° – 24° |
| 5GD | High thrust series (e.g., 313) | 31316 | 28° – 35° |
Standardized dimensions
Section titled “Standardized dimensions”The main dimensions of metric tapered roller bearings are standardized according to ISO 355. A 302 series bearing with a bore diameter of 30 mm / 1.181 in has an outside diameter of 62 mm / 2.441 in and a total width of 17,25 mm / 0.679 in. The following table lists representative dimensions for 302 series bearings (d = bore, D = outside diameter, T = total width).
| Designation (ISO example) | d (mm/in) | D (mm/in) | T (mm/in) |
|---|---|---|---|
| 30204 (2FB) | 20 mm / 0.787 in | 47 mm / 1.850 in | 15,25 mm / 0.600 in |
| 30205 (2FB) | 25 mm / 0.984 in | 52 mm / 2.047 in | 16,25 mm / 0.640 in |
| 30206 (2FB) | 30 mm / 1.181 in | 62 mm / 2.441 in | 17,25 mm / 0.679 in |
| 30207 | 35 mm / 1.378 in | 72 mm / 2.835 in | 18,25 mm / 0.719 in |
| 30208 | 40 mm / 1.575 in | 80 mm / 3.150 in | 19,75 mm / 0.778 in |
| 30210 | 50 mm / 1.969 in | 90 mm / 3.543 in | 21,75 mm / 0.856 in |
| 30212 | 60 mm / 2.362 in | 110 mm / 4.331 in | 23,75 mm / 0.935 in |
| 30215 | 75 mm / 2.953 in | 130 mm / 5.118 in | 27,25 mm / 1.073 in |
Load capacities
Section titled “Load capacities”A 32210 series tapered roller bearing (50 mm / 1.969 in bore) offers a basic dynamic load rating of 104 kN / 23 380 lbf and a static load rating of 118 kN / 26 530 lbf. Values depend on size and contact angle series; series such as 313 support higher axial load than 302 series. Equivalent loads are calculated by combining the radial and axial components using the Y factor (axial load factor). The following table shows indicative ratings for common sizes.
| Designation | Bore diameter (mm/in) | Dynamic C (kN/lbf) | Static C0 (kN/lbf) |
|---|---|---|---|
| 30206 | 30 mm / 1.181 in | 44,0 kN / 9 890 lbf | 48,5 kN / 10 900 lbf |
| 30208 | 40 mm / 1.575 in | 62,0 kN / 13 940 lbf | 71,0 kN / 15 960 lbf |
| 32210 | 50 mm / 1.969 in | 104 kN / 23 380 lbf | 118 kN / 26 530 lbf |
| 32212 | 60 mm / 2.362 in | 145 kN / 32 600 lbf | 170 kN / 38 220 lbf |
| 31310 | 50 mm / 1.969 in | 122 kN / 27 430 lbf | 140 kN / 31 470 lbf |
| 32312 | 60 mm / 2.362 in | 215 kN / 48 330 lbf | 260 kN / 58 450 lbf |
Selection criteria
Section titled “Selection criteria”The L10 rating life of a tapered roller bearing typically ranges from 5 000 h to 100 000 h depending on the application, and is calculated using the classic fatigue formula L10 = (C/P)^(10/3). Selection begins by estimating the dynamic equivalent load P, which combines radial and axial forces using the Y factor. For applications with predominant axial load, steep angle series (313, 303) are preferred, while for purely radial or light combined loads, 302 or 322 series are used. The ratio of axial to radial load determines the required contact angle: angles of 10° to 17° for Fa/Fr < 0.5 and angles ≥ 24° for ratios above 0.8. Additionally, the thermal speed limit and the need for preload to eliminate clearance and increase stiffness must be verified.
Mounting and adjustment
Section titled “Mounting and adjustment”The inner ring and cup of a tapered roller bearing are mounted separately; the axial clearance is established by displacing the inner ring relative to the cup by 0.01 mm / 0.0004 in to 0.15 mm / 0.006 in depending on size. In paired configurations (back-to-back or face-to-face mounting) the clearance must be adjusted by means of a nut or shims until zero radial clearance or a defined preload is achieved. The seats on shafts and housings require appropriate ISO tolerances: for rotating shafts an interference fit (k5 to m6) is recommended, and for fixed supports a clearance fit (H7 to J7). Induction heating (80 °C / 176 °F to 100 °C / 212 °F) facilitates mounting without damaging the raceways.
Application selection table
Section titled “Application selection table”| Application | Predominant load | Recommended series (ISO 355) | Typical diameter range (mm/in) | Notes |
|---|---|---|---|---|
| Automotive wheel hub | Radial + moderate axial | 2FB (302) | 25 mm – 80 mm / 1 in – 3.15 in | Paired mounting with controlled axial adjustment |
| Industrial transmission | High radial | 3FB (322) | 40 mm – 120 mm / 1.57 in – 4.72 in | Good load/speed ratio |
| Rear axle / differential | Combined with thrust | 4FE (323) | 50 mm – 150 mm / 1.97 in – 5.91 in | Supports high shock load |
| Planetary gearbox | Bidirectional thrust | 5GD (313) | 60 mm – 200 mm / 2.36 in – 7.87 in | High contact angle |
| Rolling mill | Severe radial and thrust | 3FC (303) or 4FE (323) | 80 mm – 500 mm / 3.15 in – 19.69 in | Used in multi-row configurations |
| Wind turbine | Variable thrust | 2FB or 3FB (302/322) | 100 mm – 600 mm / 3.94 in – 23.62 in | Requires long-life lubrication and controlled preload |
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the expected service life of a tapered roller bearing in a gearbox?
Section titled “What is the expected service life of a tapered roller bearing in a gearbox?”A tapered roller bearing operating at full load in an industrial gearbox can achieve a L10h life of 20 000 h if the C/P ratio is approximately 4. With reduced loads it can exceed 60 000 h.
What dynamic load capacity does a tapered roller bearing with a 40 mm bore have?
Section titled “What dynamic load capacity does a tapered roller bearing with a 40 mm bore have?”A 30208 bearing (40 mm / 1.575 in) has a dynamic capacity of 62 kN / 13 940 lbf, sufficient for support roller applications and intermediate shafts with moderate loads.
How is the equivalent axial load calculated in a tapered roller bearing?
Section titled “How is the equivalent axial load calculated in a tapered roller bearing?”The equivalent axial load is determined by the formula Pa = 0.4 Fr + Y Fa, where Y is the axial load factor specific to the bearing; for a 30206, Y ≈ 1.6.
What is the maximum operating temperature of a standard tapered roller bearing?
Section titled “What is the maximum operating temperature of a standard tapered roller bearing?”Thermally stabilized tapered roller bearings (S1) operate up to 150 °C / 302 °F. Exceeding 120 °C / 248 °F requires special steels and high-temperature lubrication.
What axial clearance is recommended in a face-to-face paired mounting?
Section titled “What axial clearance is recommended in a face-to-face paired mounting?”In a back-to-back mounting of 302 series bearings with a diameter of 50 mm / 1.969 in, an axial clearance of 0.03 mm / 0.0012 in to 0.05 mm / 0.0020 in is set to compensate for thermal expansion.
How much static load can a tapered roller bearing withstand without damage?
Section titled “How much static load can a tapered roller bearing withstand without damage?”A 32312 bearing withstands a static load of up to 260 kN / 58 450 lbf; exceeding it can cause plastic deformation of the raceways greater than 0.0001 of the roller diameter.
References
Section titled “References”- engineeringtoolbox.com: https://www.engineeringtoolbox.com/metric-threads-d_777.html
- mcmaster.com: https://www.mcmaster.com/products/tapered-rollers/