LM12749-LM12711 bearing: complete specifications & equivalents
The LM12749-LM12711 is a ANSI ABMA 19.2 radial bearing sized 21.986 x 45.974 x 15.494 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 21.986 mm |
| Outer diameter D | 45.974 mm |
| Width B | 15.494 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 33 kN |
| Basic static load rating C0 | 34 kN |
| Limiting speed (mechanical) | 8400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 123 g |
| Manufacturer designation | NTN 4T-LM12749/LM12711 |
| Standard | ANSI ABMA 19.2 |
| Catalog version | NTN 2203E 2026-09-25 |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN 2203E 2026-09-25) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN 2203E 2026-09-25); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 4t-inch-series range
| Bore d | 0.866 in |
|---|---|
| Outer diameter D | 1.81 in |
| Width B | 0.61 in |
| ISO bore code | 49 |
| Radial section height (D−d)/2 | 12 mm |
| Smallest bore in 4t-inch-series | 12.7 mm |
| Largest outer diameter in 4t-inch-series | 260 mm |
| Width range across 4t-inch-series | 10.998–77.788 mm |
| Bore position in 4t-inch-series (smallest first) | 12 of 148 |
| Bore above smallest 4t-inch-series size | 9.286000000000001 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| LM12749-710 | SKF | 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. |
| LM12749-711 | SKF | 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. |
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 LM12749-LM12711 model number is decoded
4T-LM12749/LM12711 is an NTN inch-series single-row tapered roller bearing: a separable cone-and-cup pair on the ABMA inch boundary plan, 21.986×45.974×15.494 mm (assembled width T), for a shaft of about 21.986 mm (0.866 in). Reading the designation: 4T-LM12749/LM12711 follows the ABMA inch convention — the number before the slash is the cone (inner ring with roller set and cage), the number after the slash is the cup (outer ring), and the light-medium LM family lettering ties the pair to its boundary plan. The 12.0 mm radial section over the 21.986 mm bore positions the contact line of the pair; abutment shoulders and spacers are dimensioned from that geometry, not from the bore alone. Cup-side note for LM12711: within the light-medium LM family tables the LM12749 cone is listed against several cup options, and it is the cup that fixes the 45.974 mm OD and the 15.494 mm assembled width — quote the full LM12749/LM12711 pair, never the cone alone. Contact-pattern check with marking blue: a pattern biased to one roller end means the 21.986 mm pair is misadjusted and the set will edge-load in service.
Typical equipment & failure modes
Common applications
- small machine-tool feed and spindle counter-supports
- light trailer and boat-trailer wheel hubs
- small agricultural implement wheels and auger drives
- lawn, garden and powersport axle positions
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- cage damage from a mounting blow transmitted through the roller complement
- rolling-contact fatigue spalling after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- At 21.986 mm (0.866 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-LM12749/LM12711 pair with a dial indicator on end play rather than by locknut feel.
- The light-medium LM family at 21.986 mm bore (45.974×15.494 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full LM12749/LM12711 reference at purchase.
- Quote the full LM12749/LM12711 pair at ordering: the LM12749 cone also ships against sibling cups, and a cup from another reference changes the 15.494 mm assembled width and the rating.
- Grease packs must leave free volume inside the 15.494 mm-wide set; over-greasing a pair churning near the oil-band speed of 11,000 r/min raises temperature and destroys the setting.
- Replacing one half of an adjusted pair without resetting end play negates the 15.494 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- The 33/34 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-LM12749/LM12711; internal geometry legitimately differs between inch-series makers, so re-verify ratings, adjustment and the exact cone/cup references before substituting another brand on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 4T-LM12749/LM12711?
4T-LM12749/LM12711 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 21.986 mm bore (0.866 in), 45.974 mm outside diameter and 15.494 mm assembled width T (1.81 × 0.61 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 33 kN, C0 34 kN, grease limiting speed 8,400 r/min, oil speed 11,000 r/min, mass about 123 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-LM12749/LM12711 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the LM12749 cone or the LM12711 cup can be replaced by an identical reference from NTN or another ABMA-dimensioned maker. Pairing the cone with a different cup reference is a different catalogue row: OD, assembled T and the 33/34 kN ratings change with the cup.
What is the difference between 4T-LM12749/LM12711 and a metric ISO 355 tapered bearing?
4T-LM12749/LM12711 follows the ABMA inch boundary plan with cone/cup references; ISO 355 bearings use metric dimension-series numbers (302, 322, …). Even where a metric size looks close to 21.986×45.974×15.494 mm, the envelopes and contact angles differ — the two systems are not drop-in interchangeable; check every boundary value before substituting.
What does the 4T prefix on 4T-LM12749/LM12711 mean?
4T is NTN's tapered roller bearing quality mark, stamped on cone and cup in the factory. It identifies NTN's 4T programme and is not a dimension or variant code, so interchange lists quote the bare LM12749/LM12711 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-LM12749/LM12711 list two speeds, 8,400 and 11,000 r/min?
The lower figure, 8,400 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 4T-LM12749/LM12711 at 11,000 r/min because oil removes rib-contact heat better. Real limits still depend on pair adjustment, oil flow and cooling.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN 2203E 2026-09-25 on 2026-10-01. Read our editorial & correction policy.