33108-DF bearing: complete specifications & equivalents
The 33108-DF is a ISO 355 radial bearing sized 40 x 75 x 52 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 | 52 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 167 kN |
| Basic static load rating C0 | 208 kN |
| Fatigue load limit Pu | 22.8 kN |
| Reference speed (thermal) | 6000 rpm |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1050 g |
| Manufacturer designation | SKF 33108/DF |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants |
| Last verified | 2026-09-29 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants) · extracted 2026-09-29
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants); 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 & matched-df-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 2.047 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in matched-df-series | 25 mm |
| Largest outer diameter in matched-df-series | 540 mm |
| Width range across matched-df-series | 34.5–280 mm |
| Bore position in matched-df-series (smallest first) | 4 of 35 |
| Bore above smallest matched-df-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33108 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
| 33108-NTN | NTN | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
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-DF model number is decoded
Operating context for the 40 mm bore: a shaft of this diameter typically runs in the medium-bore band of industrial duty, and the 75 mm OD places the housing shoulder near 83 mm outer abutment. Spacer discipline: the spacer between the two bearings of 33108-DF is ground to the individual set — it carries a serial link to the pair, so never swap spacers between sets of the same designation. Lubrication for the pair should be sized against the combined 52 mm width and 1050 g mass: two roller sets sweep twice the contact area of a single bearing of the same bore.Ordering number SKF 33108/DF in SKF catalogue PUB BU/P1 17000 denotes two single-row tapered roller bearings supplied as a matched face-to-face (X) matched pair set for a 40 mm shaft — one order number, one factory setting.Reading the designation: 33108 is the ISO 355 single-row base bearing (40 mm bore), and the suffix /DF marks the matched-set execution — arrangement, spacer grinding and factory clearance class. The pair envelope is 40×75×52 mm; the width covers both bearings of the set. Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 33108-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 40 mm bore. With a pair mass of 1050 g across the 40×75×52 mm envelope, the set replaces what would otherwise be two separate bearings plus spacer grinding work — the factory setting is the engineering value being purchased.
Typical equipment & failure modes
Common applications
- machine-tool spindles
- belt-driven fan and blower shafts
- axle-boxes in material-handling equipment
- belt-driven fan and blower shafts
Known failure patterns
- roller large-end smearing against the cone rib after EP lubricant film failure
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- 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
- brinelling from pressing the cone or cup home through the rollers
Selection pitfalls — read before you substitute
- Setting is built into 33108-DF; the classic field error is re-adjusting a matched pair as if it were two loose single bearings, which destroys the /DF clearance class.
- Setting is built into 33108-DF; the classic field error is re-adjusting a matched pair as if it were two loose single bearings, which destroys the /DF clearance class.
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 33108-DF concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- The 167/208 kN ratings are SKF catalogue 17000 values for this 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.
- Quote the full SKF 33108/DF designation when purchasing — base-number-only orders are ambiguous across executions and variants.
Frequently asked questions
What are the dimensions and catalogue data of 33108-DF?
The SKF 33108/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 40 mm bore, 75 mm outer diameter and 52 mm overall width (1.575 × 2.953 × 2.047 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 167 kN, C0 208 kN, fatigue load limit Pu 22.8 kN, reference speed 6,000 r/min, limiting speed 9,000 r/min, mass about 1.05 kg.
What does the /DF suffix on 33108-DF mean?
The base 33108 is the ISO 355 single-row bearing; the /DF suffix marks the matched-set execution — the arrangement (face-to-face (X)), the ground spacer and the factory-set axial clearance class. A matched set cannot be assembled from loose single bearings; quote the full designation when ordering.
Are the C and C0 ratings of 33108-DF for one bearing or the pair?
They are for the complete matched pair: C 167 kN dynamic and C0 208 kN static already include load sharing between the two bearings. Do not halve them for single-bearing checks, and do not compare them directly with the single-row 33108 table values.
Can 33108-DF be adjusted like two loose tapered bearings?
No — the axial clearance is set at the factory by selective spacer grinding. Mounting work is limited to clean seats, correct fits (k5 on a rotating 40 mm shaft) and axial clamping through the cones; re-setting in the field destroys the matched clearance class.
When should a face-to-face (X) matched set be chosen?
Choose the face-to-face (X) set where the shaft grows thermally or alignment is imperfect — the converging load lines tolerate deflection. It is the default choice for wheel hubs and general gearbox shafts at the 40 mm bore.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants on 2026-09-29. Read our editorial & correction policy.