29685-29620 bearing: complete specifications & equivalents
The 29685-29620 is a ISO 355 radial bearing sized 73.025 x 112.712 x 25.4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 73.025 mm |
| Outer diameter D | 112.712 mm |
| Width B | 25.4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 121 kN |
| Basic static load rating C0 | 156 kN |
| Fatigue load limit Pu | 17.6 kN |
| Reference speed (thermal) | 4500 rpm |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 890 g |
| Manufacturer designation | SKF 29685/29620 |
| 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 & 29600-series range
| Bore d | 2.875 in |
|---|---|
| Outer diameter D | 4.437 in |
| Width B | 1 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.8 mm |
| Smallest bore in 29600-series | 69.85 mm |
| Largest outer diameter in 29600-series | 112.712 mm |
| Width range across 29600-series | 25.4–25.4 mm |
| Bore position in 29600-series (smallest first) | 2 of 2 |
| Bore above smallest 29600-series size | 3.1750000000000114 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 29685-29620-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 73.025×112.712×25.4 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 29685-29620 | 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 29685-29620 model number is decoded
Ordering number SKF 29685/29620 in SKF catalogue PUB BU/P1 17000 denotes a single-row tapered roller bearing for a 73.025 mm shaft, inch series, with an open pressed-steel-cage execution and one-direction axial capacity.The 29600-series series assigns 73.025 mm bore, 112.712 mm OD and 25.4 mm width to 29685; the cone and cup references are not interchangeable with other inch-series pairs even when the bore matches, because the cup profile and rib geometry are series-specific. SKF lists the plain number as the basic execution; letter suffixes such as B denote a steeper contact angle and are different order numbers. Speed planning uses two different ceilings: 4,500 r/min thermal reference and 5,300 r/min mechanical limiting speed. A single 29685 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 121 kN basic dynamic rating C and 156 kN static rating C0 give a C0/C balance of 1.29, and dividing C by the 73.025 mm bore yields 1.66 kN per millimetre of journal — a density metric that compares across families; the 17.6 kN fatigue limit Pu is the floor beneath which the adjusted-life calculation drops below acceptable L10 hours for a 73.025 mm shaft carrying variable duty. Within the 29600-series tables, 29685 appears in several rows because SKF lists multiple cup options for the same cone. 29685 is the 29620 variant, with 112.712 mm OD and 25.4 mm width; neighbouring rows on the same cone differ only in the cup but are separate orderable bearings.
Typical equipment & failure modes
Common applications
- large process pump and compressor shafts
- rolling-mill auxiliary drives
- crane sheave and hoist gearboxes
- large process pump and compressor 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
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- 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
- Mount the 73.025 mm bore 29685 by induction heating of the cone (max 120 °C — the pressed-steel cage sets the ceiling, not the steel); driving it home through the cup or rollers brinells the tapered raceway.
- The 29600-series inch series at 73.025 mm bore (112.712×25.4 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.
- At the 121 kN rating of 29685, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 5,300 r/min speed end and heavier preload only where moment stiffness dominates.
- When the outer ring rotates, reverse the fit logic and provide cup location; the tapered contact of 29685 pushes the rings apart under load, so a non-located cup walks its seat even when the shaft is fixed.
- The 29685 shares its ISO 355 envelope with other tapered bearings of the same code but is not a drop-in replacement for a ball bearing: it cannot run effectively under pure radial load without a minimum axial load, and a deep-groove bearing cannot replace its combined-load duty.
- The 121/156 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 29685 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 29685/29620 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 29685?
The SKF 29685/29620 is a single-row tapered roller bearing with 73.025 mm bore, 112.712 mm outer diameter and 25.4 mm width (2.875 × 4.437 × 1 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 121 kN, C0 156 kN, fatigue load limit Pu 17.6 kN, reference speed 4,500 r/min, limiting speed 5,300 r/min, mass about 890 g. It is an open, separable bearing with a pressed-steel cage.
How does the 29685 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 29600-series code marks the dimensional series. The metric dimensions 73.025×112.712×25.4 mm are the converted equivalents of the original inch boundary dimensions.
What do the cone and cup numbers in 29685 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 (29600-series) groups sizes that share the same boundary-dimension plan.
Can a single 29685 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 29685 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 29685 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.