61976 bearing: complete specifications & equivalents
The 61976 is a ISO 15 radial bearing sized 380 x 520 x 65 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 380 mm |
| Outer diameter D | 520 mm |
| Width B | 65 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 360 kN |
| Basic static load rating C0 | 510 kN |
| Fatigue load limit Pu | 15.9 kN |
| Limiting speed (mechanical) | 1100 rpm |
| Mass | 39800 g |
| Manufacturer designation | NTN 6976 |
| 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 | 14.961 in |
|---|---|
| Outer diameter D | 20.472 in |
| Width B | 2.559 in |
| ISO bore code | 76 |
| Radial section height (D−d)/2 | 70 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) | 41 of 46 |
| Bore above smallest 61900-series size | 370 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61976 | 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 61976 model number is decoded
In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61976 carries bore code 76 = 380 mm. Outside diameter 520 mm and width 65 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 380 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
- robotics and automation joints
- lay shafts and idler shafts
- textile machinery
- packaging machinery
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 380 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 (70.0 mm section height at 380 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
- The open 61976 has no lubricant retention: grease escapes and contaminants migrate straight into the 380×520×65 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 61976 units.
- Do not quieten a noisy bearing by preloading it: the 61900-series is a deep-groove design, not angular-contact; axial preload raises temperature and shortens grease life.
- The open 61976 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 360/510 kN load ratings, 15.9 kN fatigue load limit Cu and 39800 g mass here are NTN Ball and Roller Bearings CAT.No.2203-3/E figures for 6976; 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 61976 bearing?
A 61976 deep-groove ball bearing has a 380 mm bore, 520 mm outer diameter and 65 mm width (14.961 × 20.472 × 2.559 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields.
How does the 61976 bore code work?
The last two digits of 61976 are bore code 76, giving 76 × 5 = 380 mm bore. The 520 mm outside diameter and 65 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61976 mean?
A bare 61976 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 380 mm bore?
619 is a thin section one step above 618: 520×65 mm with a 70.0 mm radial section at 380 mm bore; a 6276 on the same bore is substantially larger and more heavily rated.
What is the NTN designation and catalogue data for 61976?
In the NTN Ball and Roller Bearings catalogue (CAT.No.2203-3/E, 2024) this size is listed as 6976 — the open (unsealed) execution, 380×520×65 mm per ISO 15. Quoted values: C 360 kN, C0 510 kN, Cu 15.9 kN, mass 39800 g. Grease limiting speed 1100 rpm. The industry-neutral page spelling 61976 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.