36990-36920 bearing: complete specifications & equivalents
The 36990-36920 is a ISO 355 radial bearing sized 177.8 x 227.012 x 30.162 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 177.8 mm |
| Outer diameter D | 227.012 mm |
| Width B | 30.162 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 231 kN |
| Basic static load rating C0 | 425 kN |
| Fatigue load limit Pu | 40 kN |
| Reference speed (thermal) | 2000 rpm |
| Limiting speed (mechanical) | 2400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2950 g |
| Manufacturer designation | SKF 36990/36920 |
| 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 & 36900-series range
| Bore d | 7 in |
|---|---|
| Outer diameter D | 8.937 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 24.6 mm |
| Smallest bore in 36900-series | 177.8 mm |
| Largest outer diameter in 36900-series | 227.012 mm |
| Width range across 36900-series | 30.162–30.162 mm |
| Bore position in 36900-series (smallest first) | 1 of 1 |
| Bore above smallest 36900-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 36990-36920-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 177.8×227.012×30.162 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 36990-36920 | 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 36990-36920 model number is decoded
Cup-side note for 36920: the outer ring's rib profile and the 227.012 mm outside diameter are cup-specific within the 36900-series tables, so substituting a different cup against the same 36990 cone changes both the assembled 30.162 mm width and the axial free-play setting of the mounted pair.In SKF catalogue PUB BU/P1 17000, 36990 appears as SKF 36990/36920: an open, single-row tapered roller bearing in the 36900-series, supplied with a pressed-steel cage as standard.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 (36900-series) ties the pair to a specific boundary plan. Dimensions 177.8×227.012×30.162 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. With C 231 kN and C0 425 kN, the 36990 pair-sizing check is dominated by the axial share: keep the equivalent load P below the rating at the required L10, remembering one bearing alone cannot cover reversing thrust at 2,400 r/min. Specify pairs rather than single units wherever thrust reverses: the tapered contact of 36990 generates an induced axial load under radial force, and an unpaired bearing on a reversing shaft will run slack and fret its seat. Load system: the 231 kN basic dynamic rating C and 425 kN static rating C0 give a C0/C balance of 1.84, and dividing C by the 177.8 mm bore yields 1.30 kN per millimetre of journal — a density metric that compares across families; the 40 kN fatigue limit Pu is the floor beneath which the adjusted-life calculation drops below acceptable L10 hours for a 177.8 mm shaft carrying variable duty.
Typical equipment & failure modes
Common applications
- large industrial mixer shafts
- offshore winch and drawworks drums
- rolling-mill roll-neck bearings
- wind-turbine main 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
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- At 177.8 mm bore the cone mass is high enough that cocking during mounting damages the cage and rib; guide the ring square, confirm seat contact around the full circumference, and re-check setting after the first thermal cycle of the paired set.
- The 320 series at 177.8 mm bore (227.012×30.162 mm) is the low-friction, higher-speed section; it carries less thrust than a 302 of the same bore, so verify the axial load share before swapping.
- Do not mix brands or executions inside one 36990 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.
- At the 231 kN rating of 36990, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 2,400 r/min speed end and heavier preload only where moment stiffness dominates.
- Shaft and housing fillets must clear the bearing chamfer so the 30.162 mm-wide cup seats square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 231/425 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 36990 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 36990/36920 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
Is 36990 interchangeable with other brands?
Inch-series tapered roller bearings follow a long-standing industry boundary plan, so cones and cups of the same basic number are generally dimensionally interchangeable across manufacturers. However, internal geometry, cage design and load ratings differ by brand, so for paired or precision applications keep both halves of the set from one manufacturer — or re-verify ratings and setting when mixing.
What are the dimensions and catalogue data of 36990?
The SKF 36990/36920 is a single-row tapered roller bearing with 177.8 mm bore, 227.012 mm outer diameter and 30.162 mm width (7 × 8.937 × 1.187 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 231 kN, C0 425 kN, fatigue load limit Pu 40 kN, reference speed 2,000 r/min, limiting speed 2,400 r/min, mass about 2950 g. It is an open, separable bearing with a pressed-steel cage.
How does the 36990 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 36900-series code marks the dimensional series. The metric dimensions 177.8×227.012×30.162 mm are the converted equivalents of the original inch boundary dimensions.
What do the cone and cup numbers in 36990 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 (36900-series) groups sizes that share the same boundary-dimension plan.
Can a single 36990 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.
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.