LM503349A-310 bearing: complete specifications & equivalents
The LM503349A-310 is a ISO 355 radial bearing sized 46 x 75 x 18 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 46 mm |
| Outer diameter D | 75 mm |
| Width B | 18 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 62.1 kN |
| Basic static load rating C0 | 71 kN |
| Fatigue load limit Pu | 7.65 kN |
| Reference speed (thermal) | 7000 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 300 g |
| Manufacturer designation | SKF LM 503349 A/310 |
| 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 & LM503300-series range
| Bore d | 1.811 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 0.709 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 14.5 mm |
| Smallest bore in LM503300-series | 46 mm |
| Largest outer diameter in LM503300-series | 75 mm |
| Width range across LM503300-series | 18–18 mm |
| Bore position in LM503300-series (smallest first) | 1 of 1 |
| Bore above smallest LM503300-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| LM503349A-LM503310 | 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. |
| LM503349A-310 | 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 LM503349A-310 model number is decoded
For a 46 mm shaft carrying combined load, SKF lists LM503349A under catalogue execution SKF LM 503349 A/310: one open single-row tapered roller bearing in the inch LM503300-series.The LM503300-series series assigns 46 mm bore, 75 mm OD and 18 mm width to LM503349A; 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. In SKF suffix language a bare LM503349A is the standard execution; B marks a larger contact angle and Q or J2 mark clearance/cage variants, all quoted separately. Speed planning uses two different ceilings: 7,000 r/min thermal reference and 8,500 r/min mechanical limiting speed. Specify pairs rather than single units wherever thrust reverses: the tapered contact of LM503349A generates an induced axial load under radial force, and an unpaired bearing on a reversing shaft will run slack and fret its seat. Speed envelope and thermal behaviour: at 7,000 r/min thermal reference, the 46 mm bore shaft runs at a dn of 322k, and the 14.5 mm section dissipates heat through the cup-to-housing contact path; the 8,500 r/min mechanical ceiling reflects cage strength, and the 300 g spinning cone contributes gyroscopic moment under rapid speed reversal. Cup-side note for 310: the outer ring's rib profile and the 75 mm outside diameter are cup-specific within the LM503300-series tables, so substituting a different cup against the same LM 503349 A cone changes both the assembled 18 mm width and the axial free-play setting of the mounted pair.
Typical equipment & failure modes
Common applications
- industrial gearbox shafts and reducers
- differential and pinion drives
- pump and compressor shafts
- industrial gearbox shafts and reducers
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
- electrical pitting on VFD-driven shafts without grounding protection
Selection pitfalls — read before you substitute
- On this 46 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 LM503349A pair heats, loses setting control and smears the roller-rib contact.
- The LM503300-series inch series at 46 mm bore (75×18 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 62.1 kN rating of LM503349A, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 8,500 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 LM503349A pushes the rings apart under load, so a non-located cup walks its seat even when the shaft is fixed.
- The 300 g mass and 18 mm width mean spacer and abutment faces must be square to the axis within the bearing's own P0 tolerance; a tilted spacer tilts the contact angle and concentrates load on one rib of LM503349A.
- The 62.1/71 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 LM503349A (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF LM 503349 A/310 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of LM503349A?
The SKF LM 503349 A/310 is a single-row tapered roller bearing with 46 mm bore, 75 mm outer diameter and 18 mm width (1.811 × 2.953 × 0.709 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 62.1 kN, C0 71 kN, fatigue load limit Pu 7.65 kN, reference speed 7,000 r/min, limiting speed 8,500 r/min, mass about 300 g. It is an open, separable bearing with a pressed-steel cage.
How does the LM503349A 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 LM503300-series code marks the dimensional series. The metric dimensions 46×75×18 mm are the converted equivalents of the original inch boundary dimensions.
What do the cone and cup numbers in LM503349A 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 (LM503300-series) groups sizes that share the same boundary-dimension plan.
Can a single LM503349A 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 LM503349A 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 LM503349A 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.