51409 bearing: complete specifications & equivalents
The 51409 is a ISO 104 radial bearing sized 45 x 100 x 39 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 39 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 130 kN |
| Basic static load rating C0 | 242 kN |
| Fatigue load limit Pu | 10.9 kN |
| Limiting speed (mechanical) | 1600 rpm |
| Mass | 1430 g |
| Manufacturer designation | 51409 |
| Standard | ISO 104 |
| Catalog version | CAT. No. 2203-3/E 2024 |
| Last verified | 2026-09-25 |
Source: catalog reference (CAT. No. 2203-3/E 2024) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (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 & 51400-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.535 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 51400-series | 25 mm |
| Largest outer diameter in 51400-series | 210 mm |
| Width range across 51400-series | 24–85 mm |
| Bore position in 51400-series (smallest first) | 5 of 15 |
| Bore above smallest 51400-series size | 20 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 51409 model number is decoded
In the 51400-series (ISO 104 dimension series) the leading digits 514 mark a single-direction thrust ball bearing and the last two digits encode the bore: 51409 carries bore code 09 = 45 mm. The ISO 104 boundary dimensions are 45 mm bore, 100 mm outside diameter and 39 mm height. Two flat washers (shaft and housing) and a ball cage assembly allow the bearing to carry pure axial load in one direction while accommodating minor misalignment.
Typical equipment & failure modes
Common applications
- conveyor drive thrust washers
- agricultural equipment spindle thrust
- industrial fan axial restraint
- electric motor axial positioning
Known failure patterns
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- cage wear or fracture from sustained vibration or shock loading
- false brinelling from vibration while the shaft is stationary
Selection pitfalls — read before you substitute
- At a 45 mm bore, check shaft shoulder runout before fitting 51409; a skewed shoulder tilts the shaft washer and concentrates load on a few balls.
- The 514xx heavy section at 45 mm bore (100 mm OD) is built for high-load, lower-speed duty; specifying it in a high-rpm application gives excess heat and short grease life — use 511/512 there.
- Minimum axial load is required to prevent ball skidding: at very light loads the balls slide rather than roll, causing smearing and early failure.
- The shaft washer (bore 45 mm) must be a tight fit on the shaft; the housing washer should be loose in the housing to allow self-alignment.
Frequently asked questions
What are the dimensions of a 51409 thrust ball bearing?
A 51409 thrust ball bearing has a 45 mm bore, 100 mm outside diameter and 39 mm height, per ISO 104 boundary dimensions. It consists of a shaft washer, housing washer and ball cage assembly.
How does the 51409 bore code work?
The last two digits of 51409 are bore code 09, giving 09 × 5 = 45 mm bore. The 100 mm outside diameter and 39 mm height follow the ISO 104 dimension series, not the bore code alone.
Can a 51409 thrust ball bearing carry radial load?
No. Single-direction thrust ball bearings carry axial load only. Any radial component must be supported by a separate radial bearing (deep-groove, cylindrical roller or spherical roller).
How does the 51400 compare with other thrust series at the same 45 mm bore?
The 514xx is the heavy section: 100×39 mm, 27.5 mm radial section at 45 mm bore — the highest-capacity single-direction thrust option here, aimed at lower-speed, high-load shafts.
Reviewed & verified by the MPN Base engineering desk against source catalog CAT. No. 2203-3/E 2024 on 2026-09-25. Read our editorial & correction policy.