M12649-610 bearing: complete specifications & equivalents
The M12649-610 is a ISO 355 radial bearing sized 21.43 x 50.005 x 17.526 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 21.43 mm |
| Outer diameter D | 50.005 mm |
| Width B | 17.526 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 45.4 kN |
| Basic static load rating C0 | 38 kN |
| Fatigue load limit Pu | 4.15 kN |
| Reference speed (thermal) | 12000 rpm |
| Limiting speed (mechanical) | 15000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 170 g |
| Manufacturer designation | SKF M 12649/610 |
| 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 & M12600-series range
| Bore d | 0.844 in |
|---|---|
| Outer diameter D | 1.969 in |
| Width B | 0.69 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 14.3 mm |
| Smallest bore in M12600-series | 21.43 mm |
| Largest outer diameter in M12600-series | 50.005 mm |
| Width range across M12600-series | 17.526–17.526 mm |
| Bore position in M12600-series (smallest first) | 1 of 1 |
| Bore above smallest M12600-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| M12649-M12610 | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
| M12649-610 | 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 M12649-610 model number is decoded
For a 21.43 mm shaft carrying combined load, SKF lists M12649 under catalogue execution SKF M 12649/610: one open single-row tapered roller bearing in the inch M12600-series.The code breaks down as cone/cup: the numbers before and after the slash identify the inner and outer ring sets, and the series prefix (M12600-series) ties the pair to a specific boundary plan. Dimensions 21.43×50.005×17.526 mm are the converted metric envelope. The SKF catalogue adds the ISO 355 dimension-series code after the bare number (e.g. ); it is the dimensional series, not a separate part number. At 12,000 r/min reference speed the 14.3 mm-section M12649 is governed thermally by preload and lubricant flow; grease or oil selection should be made against that value, with 15,000 r/min as the mechanical ceiling. A single M12649 locates the shaft in one axial direction only; mount it against a second bearing in O (back-to-back) or X (face-to-face) arrangement, and set the running clearance by the mounting procedure — not by feel. Load system: the 45.4 kN basic dynamic rating C and 38 kN static rating C0 give a C0/C balance of 0.84, and dividing C by the 21.43 mm bore yields 2.12 kN per millimetre of journal — a density metric that compares across families; the 4.15 kN fatigue limit Pu is the floor beneath which the adjusted-life calculation drops below acceptable L10 hours for a 21.43 mm shaft carrying variable duty. Inch tapered bearings are matched sets, not mix-and-match components: M12649 pairs the M 12649 cone with the 610 cup under the M12600-series boundary plan, and although the same cone shows up against other cups in the catalogue, each pairing yields a distinct assembled width and a distinct rating row.
Typical equipment & failure modes
Common applications
- power-tool gear heads
- small automotive wheel hubs and trailer axles
- light-duty gearbox input/output shafts
- power-tool gear heads
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
- false brinelling on idle paired sets exposed to machine vibration
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- rib-roller contact scoring from loss of the EP additive film
Selection pitfalls — read before you substitute
- At a 21.43 mm bore the thin cone and cup are easily distorted by an over-tight shaft nut; check seat runout (target Ra ≤ 0.8 µm) and torque the locknut progressively — a pinched M12649 shows up as gearbox vibration long before it fails.
- The M12600-series inch series at 21.43 mm bore (50.005×17.526 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.
- A single M12649 cannot locate the shaft axially in both directions; mounting it singly on a reversing-thrust shaft leaves one direction uncontrolled — always use an O or X matched pair for bidirectional location.
- At the 45.4 kN rating of M12649, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 15,000 r/min speed end and heavier preload only where moment stiffness dominates.
- Open M12649 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 45.4/38 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 M12649 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF M 12649/610 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of M12649?
The SKF M 12649/610 is a single-row tapered roller bearing with 21.43 mm bore, 50.005 mm outer diameter and 17.526 mm width (0.844 × 1.969 × 0.69 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 45.4 kN, C0 38 kN, fatigue load limit Pu 4.15 kN, reference speed 12,000 r/min, limiting speed 15,000 r/min, mass about 170 g. It is an open, separable bearing with a pressed-steel cage.
How does the M12649 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 M12600-series code marks the dimensional series. The metric dimensions 21.43×50.005×17.526 mm are the converted equivalents of the original inch boundary dimensions.
What do the cone and cup numbers in M12649 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 (M12600-series) groups sizes that share the same boundary-dimension plan.
Can a single M12649 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 M12649 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 M12649 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. 8.2 inch single-row TRB on 2026-09-28. Read our editorial & correction policy.