2789-2729 bearing: complete specifications & equivalents
The 2789-2729 is a ISO 355 radial bearing sized 39.688 x 76.2 x 23.812 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 39.688 mm |
| Outer diameter D | 76.2 mm |
| Width B | 23.812 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 92.1 kN |
| Basic static load rating C0 | 93 kN |
| Fatigue load limit Pu | 10.4 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 480 g |
| Manufacturer designation | SKF 2789/2729 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB |
| Last verified | 2026-09-28 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB) · extracted 2026-09-28
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch 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 & 2700-series range
| Bore d | 1.563 in |
|---|---|
| Outer diameter D | 3 in |
| Width B | 0.937 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 18.3 mm |
| Smallest bore in 2700-series | 38.1 mm |
| Largest outer diameter in 2700-series | 76.2 mm |
| Width range across 2700-series | 23.812–23.812 mm |
| Bore position in 2700-series (smallest first) | 2 of 2 |
| Bore above smallest 2700-series size | 1.588000000000001 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 2789-2720 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 39.688×76.2×23.812 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 2789-2729 | Timken | full Dimensions and internal design equivalent — standard interchange. | Same inch-series cone/cup boundary envelope (d/D/T); load ratings and speed limits are brand-specific and may differ. |
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 2789-2729 model number is decoded
On the SKF nameplate, 2789 denotes a matched cone-and-cup pair: the designation is not a single number but a cone reference and cup reference joined by a slash, with the 2700-series marking the dimensional series. In SKF suffix language a bare 2789 is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. At 7,500 r/min reference speed the 18.3 mm-section 2789 is governed thermally by preload and lubricant flow; grease or oil selection should be made against that value, with 9,000 r/min as the mechanical ceiling. For a 39.688 mm shaft the usual cone seat is k5 with an H7 housing when the inner ring rotates; arrange two 2789 bearings as a set for two-direction location and set clearance from the load diagram, never from assembly feel. Operating context for the 39.688 mm bore: a shaft of this diameter in the medium-bore band typically runs between 31750 and 47626 r/min in real machinery, and the 76.2 mm outside diameter places the housing shoulder at 84 mm outer abutment; the 23.812 mm width and 480 g mass together set the shaft critical speed and the housing resonance check for this 27800-series envelope. Two catalogue entries share the 2789 cone but use different cups; this one, 2789, takes the 2729 cup and is ground for the resulting 76.2 mm OD / 23.812 mm width envelope. Selecting a sibling cup produces a different boundary plan and a different order number, so the full designation is required at purchase.For a 39.688 mm shaft carrying combined load, SKF lists 2789 under catalogue execution SKF 2789/2729: one open single-row tapered roller bearing in the inch 2700-series.
Typical equipment & failure modes
Common applications
- belt-driven fan and blower shafts
- axle-boxes in material-handling equipment
- automotive and light-truck wheel hubs
- automotive and light-truck wheel hubs
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
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- brinelling from pressing the cone or cup home through the rollers
Selection pitfalls — read before you substitute
- On this 39.688 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 2789 pair heats, loses setting control and smears the roller-rib contact.
- The 2700-series inch series at 39.688 mm bore (76.2×23.812 mm) follows the Timken cone/cup convention; substitutions must match both the cone and cup reference exactly — interchanging with another series or a metric 3xxxx bearing of the same bore changes OD, width and contact angle, so re-run the pair setting and shoulder-diameter checks before swapping.
- Setting is a design value, not an assembly feel: excessive preload in the 2789 pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
- Do not mix brands or executions inside one 2789 pair — matched sets are ground for a specific setting, and pairing a SKF basic unit with a different suffix variant will not share the setting evenly.
- Open 2789 units need application-supplied sealing and a defined EP lubricant supply; the roller-rib contact is the first to fail when the additive film breaks down.
- The 92.1/93 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 2789 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 2789/2729 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
How does the 2789 inch-series designation work?
Inch-series tapered roller bearings use a Timken-style cone/cup convention: the number before the slash identifies the cone (inner ring with roller and cage assembly), the number after the slash identifies the cup (outer ring), and the 2700-series code marks the dimensional series. The metric dimensions 39.688×76.2×23.812 mm are the converted equivalents of the original inch boundary dimensions.
What do the cone and cup numbers in 2789 mean?
The cone number (before the slash) identifies the inner ring, rollers and cage; the cup number (after the slash) identifies the outer ring. Both are quoted together because a single-row tapered roller bearing is a matched separable pair — the cone and cup are ground to work together and are not interchangeable with arbitrary other parts. The series prefix (2700-series) groups sizes that share the same boundary-dimension plan.
Can a single 2789 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 2789 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 2789 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
What shaft and housing fits suit 2789?
For a rotating shaft under normal load, seat the cone on a k5 shaft fit; the cup is usually a loose-to-transition fit in the housing so it can creep slightly and distribute wear. Chamfer and shoulder diameters must clear the bearing rings so the 23.812 mm-wide cup seats square; the mounting setting (end play or preload) is set by the axial position of the cup relative to the cone.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.2 inch single-row TRB on 2026-09-28. Read our editorial & correction policy.