33109 bearing: complete specifications & equivalents
The 33109 is a ISO 355 radial bearing sized 45 x 80 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 | 45 mm |
| Outer diameter D | 80 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 | 104 kN |
| Basic static load rating C0 | 114 kN |
| Fatigue load limit Pu | 12.9 kN |
| Reference speed (thermal) | 6700 rpm |
| Limiting speed (mechanical) | 8000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 550 g |
| Manufacturer designation | SKF 33109 |
| 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 | 1.772 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.024 in |
| ISO bore code | 09 |
| 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) | 2 of 12 |
| Bore above smallest 33100-series size | 5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33109 | 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 33109 model number is decoded
The SKF 33109 is a 45×80×26 mm single-row tapered roller bearing — the light wide section entry in the 33100 series, with an asymmetric raceway cut for thrust capacity and separable mounting.Reading the designation: the leading 3 marks a single-row tapered roller bearing, the 31 is the ISO 355 diameter/width series (light wide section), and the last two digits encode the 45 mm bore; the 80 mm OD and 26 mm width follow the ISO 355 general plan. In SKF suffix language a bare 33109 is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. The 17.5 mm radial section height ((80−45)/2) and 550 g catalogue mass frame a 45 mm bore bearing rated at 104 kN C — roughly 2.31 kN of dynamic capacity per millimetre of bore before application factors. For a 45 mm shaft the usual cone seat is k5 with an H7 housing when the inner ring rotates; arrange two 33109 bearings as a set for two-direction location and set clearance from the load diagram, never from assembly feel.
Typical equipment & failure modes
Common applications
- differential and pinion drives
- pump and compressor shafts
- machine-tool spindles
- belt-driven fan and blower 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
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- brinelling from pressing the cone or cup home through the rollers
Selection pitfalls — read before you substitute
- On this 45 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 33109 pair heats, loses setting control and smears the roller-rib contact.
- The 331 series at 45 mm bore (80×26 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.
- When the outer ring rotates, reverse the fit logic and provide cup location; the tapered contact of 33109 pushes the rings apart under load, so a non-located cup walks its seat even when the shaft is fixed.
- The tapered contact angle creates an induced axial load under pure radial force; include it in the 33109 rating calculation (and account for it in both bearings of a pair) or the unloaded bearing skids its rollers.
- Never press both rings through the wrong element during fitting: force for an interference shaft seat goes through the cone only, or brinell marks on the 80 mm cup race release as noise within the first running hours.
- The 104/114 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 33109 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 33109 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 33109?
The SKF 33109 is a single-row tapered roller bearing with 45 mm bore, 80 mm outer diameter and 26 mm width (1.772 × 3.15 × 1.024 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 104 kN, C0 114 kN, fatigue load limit Pu 12.9 kN, reference speed 6,700 r/min, limiting speed 8,000 r/min, mass about 550 g. It is an open, separable bearing with a pressed-steel cage.
How does the 33109 bore code work?
The last two digits of 33109 are bore code 09, so 09 × 5 = 45 mm bore. The 80 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 33109 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 33109 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 33109 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 33109 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.