33108 bearing: complete specifications & equivalents
The 33108 is a ISO 355 radial bearing sized 40 x 75 x 26 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 75 mm |
| Width B | 26 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 97.5 kN |
| Basic static load rating C0 | 104 kN |
| Fatigue load limit Pu | 11.4 kN |
| Reference speed (thermal) | 7000 rpm |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 500 g |
| Manufacturer designation | SKF 33108 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 33100-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 1.024 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in 33100-series | 40 mm |
| Largest outer diameter in 33100-series | 180 mm |
| Width range across 33100-series | 26–56 mm |
| Bore position in 33100-series (smallest first) | 1 of 12 |
| Bore above smallest 33100-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33108 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 355 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 33108 model number is decoded
33108 is a single-row tapered roller bearing in the ISO 33100 dimension series: a separable cone-and-cup design for combined radial and one-direction axial load, listed by SKF in SKF catalogue PUB BU/P1 17000.The code breaks down as type prefix 3 (tapered roller), series 31 (the light wide section), and bore code 08 = 40 mm; dimensions 40×75×26 mm therefore match the ISO 355 envelope. In SKF suffix language a bare 33108 is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. Selection arithmetic: the C0/C ratio is about 1.07 (static 104 kN against dynamic 97.5 kN), typical of a tapered roller sized for axial capacity, and the 11.4 kN fatigue load limit Pu is the equivalent-load floor used in the life calculation. Because the contact line is tapered, one 33108 reacts thrust in a single direction; bidirectional shafts need an O or X pair, and a rotating cone on a 40 mm shaft typically takes a k5 seat with an H7 housing bore.
Typical equipment & failure modes
Common applications
- automotive and light-truck wheel hubs
- industrial gearbox shafts and reducers
- differential and pinion drives
- pump and compressor shafts
Known failure patterns
- cup or cone misalignment when the separable rings are not seated square during mounting
- loose cup rotation in the housing when the specified press fit is not achieved
- false brinelling on idle paired sets exposed to machine vibration
- roller large-end smearing against the cone rib after EP lubricant film failure
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- On this 40 mm bore, interference and temperature rise consume clearance inside a preloaded pair; calculate the residual clearance after mounting and at operating temperature — an over-tight 33108 pair heats, loses setting control and smears the roller-rib contact.
- The 331 series at 40 mm bore (75×26 mm) pairs a small OD with a wide section — a compact way to add capacity where radial space is tight; abutment and spacer widths differ from the 330/302 families, so it is not a drop-in swap.
- At the 97.5 kN rating of 33108, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 9,000 r/min speed end and heavier preload only where moment stiffness dominates.
- O (back-to-back) pairs are stiffer against moments, X (face-to-face) pairs tolerate misalignment and thermal growth better; choosing the arrangement from the 2D drawing rather than the actual shaft thermal expansion is a common 33108 mounting error.
- The 33108 shares its ISO 355 envelope with other tapered bearings of the same code but is not a drop-in replacement for a ball bearing: it cannot run effectively under pure radial load without a minimum axial load, and a deep-groove bearing cannot replace its combined-load duty.
- The 97.5/104 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
- SKF lists several executions of 33108 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 33108 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 33108?
The SKF 33108 is a single-row tapered roller bearing with 40 mm bore, 75 mm outer diameter and 26 mm width (1.575 × 2.953 × 1.024 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 97.5 kN, C0 104 kN, fatigue load limit Pu 11.4 kN, reference speed 7,000 r/min, limiting speed 9,000 r/min, mass about 500 g. It is an open, separable bearing with a pressed-steel cage.
How does the 33108 bore code work?
The last two digits of 33108 are bore code 08, so 08 × 5 = 40 mm bore. The 75 mm OD and 26 mm width come from the ISO 355 dimension-series plan, shared with other tapered bearings of the same code.
What do the 33108 series and basic execution designations mean?
The leading 3 marks a single-row tapered roller bearing; the second digit 31 is the ISO 355 series (light wide section). The SKF catalogue lists the ISO 355 dimension-series code after the bare number. A steeper-contact-angle variant (B suffix) is a different order number and is not interchangeable with the basic execution.
Can a single 33108 take axial load in both directions?
No — one single-row tapered roller bearing reacts thrust in one direction only, and under radial load its contact angle induces an axial force. Use two bearings as a matched pair: O (back-to-back) for a rigid, moment-resisting arrangement, X (face-to-face) where thermal expansion must be tolerated, or tandem where one-direction thrust is shared.
How does 33108 compare with a ball bearing of the same bore?
A tapered roller bearing has line contact and a steep contact angle: much higher combined axial-plus-radial capacity and shock resistance than a ball bearing of the same bore, at the cost of speed, one-direction thrust, mandatory pairing for reversing loads and a minimum axial load requirement. A ball bearing cannot be dropped into a combined-load 33108 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB on 2026-09-26. Read our editorial & correction policy.