61968 bearing: complete specifications & equivalents
The 61968 is a ISO 15 radial bearing sized 340 x 460 x 56 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 340 mm |
| Outer diameter D | 460 mm |
| Width B | 56 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 325 kN |
| Basic static load rating C0 | 430 kN |
| Fatigue load limit Pu | 14.4 kN |
| Limiting speed (mechanical) | 1200 rpm |
| Mass | 26200 g |
| Manufacturer designation | NTN 6968 |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203-3/E (2024) |
| Last verified | 2026-09-25 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203-3/E (2024)); 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 & 61900-series range
| Bore d | 13.386 in |
|---|---|
| Outer diameter D | 18.11 in |
| Width B | 2.205 in |
| ISO bore code | 68 |
| Radial section height (D−d)/2 | 60 mm |
| Smallest bore in 61900-series | 10 mm |
| Largest outer diameter in 61900-series | 650 mm |
| Width range across 61900-series | 6–78 mm |
| Bore position in 61900-series (smallest first) | 39 of 46 |
| Bore above smallest 61900-series size | 330 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61968 | ISO-INTERCHANGE | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension interchange; ratings above are NTN 2203-3/E values and differ by brand — verify 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 61968 model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61968 carries bore code 68 = 340 mm. Outside diameter 460 mm and width 56 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 340 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the NTN catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes ZZ (shields), LLB/LLF (non-contact seals), LLH (low-torque contact seal) and LLU (contact seal).
Typical equipment & failure modes
Common applications
- space-constrained gearboxes
- clutch and transmission assemblies
- robotics and automation joints
- lay shafts and idler shafts
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- brinelling from static overload or hammering during mounting
- false brinelling from vibration while the shaft is stationary
Selection pitfalls — read before you substitute
- Mount this 340 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
- The 619xx thin section (60.0 mm section height at 340 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- The open 61968 has no lubricant retention: grease escapes and contaminants migrate straight into the 340×460×56 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 61900-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61968 units.
- Assign fits by which ring rotates: an interference shaft fit for a rotating inner ring; if the outer ring rotates instead, reverse the logic — a loose rotating ring creeps and frets its seat.
- The open 61968 has no integral sealing; in the NTN 2203 catalogue the protected variants carry suffixes ZZ (non-contact steel shields), LLB/LLF (non-contact rubber seals), LLU (contact rubber seals) and LLH (a low-torque contact seal with higher speed capability than LLU). A JR or JRX suffix (as printed for some thin-section sizes) denotes a pressed-steel cage, not a seal.
- The 325/430 kN load ratings, 14.4 kN fatigue load limit Cu and 26200 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6968; this seal/size combination has no counterpart from another catalogue on this site, so the page rests on a single manufacturer source — internal geometry and ratings legitimately differ between brands, so re-verify before substituting in a rated drive.
Frequently asked questions
What are the dimensions of a 61968 bearing?
A 61968 deep-groove ball bearing has a 340 mm bore, 460 mm outer diameter and 56 mm width (13.386 × 18.11 × 2.205 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 61968 bore code work?
The last two digits of 61968 are bore code 68, giving 68 × 5 = 340 mm bore. The 460 mm outside diameter and 56 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61968 mean?
A bare 61968 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 61900 compare with other series at the same 340 mm bore?
619 is a thin section one step above 618: 460×56 mm with a 60.0 mm radial section at 340 mm bore; a 6268 on the same bore is substantially larger and more heavily rated.
What is the NTN designation and catalogue data for 61968?
In the NTN Ball and Roller Bearings catalogue (CAT.No.2203-3/E, 2024) this size is listed as 6968 — the open (unsealed) execution, 340×460×56 mm per ISO 15. Quoted values: C 325 kN, C0 430 kN, Cu 14.4 kN, mass 26200 g. Grease limiting speed 1200 rpm. The industry-neutral page spelling 61968 follows the seal-suffix convention used across this site, not NTN order-number spelling.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203-3/E (2024) on 2026-09-25. Read our editorial & correction policy.