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 |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| 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 |
| Operating temperature | -40 to +120 °C |
| Mass | 1430 g |
| Manufacturer designation | NTN 51409 |
| Standard | ISO 104 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); 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 | 300 mm |
| Width range across 51400-series | 24–120 mm |
| Bore position in 51400-series (smallest first) | 5 of 20 |
| Bore above smallest 51400-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51409-SKF | 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 51409 model number is decoded
At 45 x 100 x 39 mm, NTN 51409 sits in the extra-heavy 51400 thrust family of the single-direction thrust programme. NTN builds the number from 514 is the dimension series (extra-heavy 51400 thrust family); 09 encodes the 45 mm bore (bore code x 5). Catalogue axial dynamic rating Ca is 130 kN against C0a 242 kN — a static/dynamic ratio of 1.86 that is the signature of a thrust raceway. Size selection ends with the minimum-load check: at the 1,600 r/min class speed, the balls need a defined axial preload to keep rolling instead of skidding. On a vertical shaft, pack grease between the washers and plan a relubrication path — centrifugal effect drives grease outward and the track runs dry without it.
Typical equipment & failure modes
Common applications
- medium crane hook blocks and slewing jibs
- extruder and mixer thrust housings
- winch and capstan vertical shafts
- press and punch-machine thrust seats
Known failure patterns
- cage pocket wear and ball skid polish after long running below the minimum axial load, the balls sliding instead of rolling on the washers
- fretting between shaft washer and shaft when the seat is cut loose — the washer creeps, the centre line shifts and the balls start running off-track
- rapid flaking after radial load was allowed onto the bearing — a single-direction thrust ball bearing carries axial load only
- washer face corrosion under long standstill in humid service, later printed into the raceway as evenly spaced pitting
- lubricant starvation scoring on the raceway track when grease is thrown outward by centrifugal effect and never replaced
Selection pitfalls — read before you substitute
- In this size class the frequent miss is washer identification: keep the catalogued shaft/housing washer pairing of the 45 mm size together from unpacking to assembly.
- The 514 extra-heavy section is the top of the thrust-ball plan at this bore; beyond it the catalogue moves to spherical roller thrust bearings.
- Do not reuse a thrust bearing to "absorb" shaft thermal growth — the bearing clamps axially, so growth must be handled on the radial-bearing side of the arrangement.
- The C0a of 242 kN is a static rating: sizing continuous working thrust from C0a alone overstates what the raceway survives.
- Swapping the shaft and housing washers is an easy assembly error on the 45 mm size — the bores differ only slightly, but the wrong pairing walks off-centre under load.
- The Ca 130/C0a 242 kN ratings and 10.9 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51409; raceway geometry legitimately differs between manufacturers, so re-verify ratings and washer identification before substituting another make.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 51409?
51409 is a single-direction thrust ball bearing to ISO 104: 45 mm shaft-washer bore, 100 mm outside diameter, 39 mm stack height (1.772 x 3.937 x 1.535 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 130 kN, C0a 242 kN and a 10.9 kN fatigue load limit Pu; the grease limiting speed is 1,600 r/min and the oil rating 2,200 r/min; mass about 1430 g.
How is the 51409 designation structured?
514 is the dimension series (extra-heavy 51400 thrust family); 09 encodes the 45 mm bore (bore code x 5). The 100 mm OD and 39 mm height follow the ISO 104 boundary plan for that series.
Can 51409 carry radial load or reversing thrust?
No. The raceways contact the balls at 90 deg to the shaft, so the rating is purely axial and single-direction. Radial load must be carried by a separate radial bearing, and reversing thrust needs a second thrust bearing or a double-direction execution.
Why does NTN specify a minimum axial load for 51409?
At the 1,600 r/min class speed, centrifugal and gyroscopic effects make an under-loaded ball set skid and smear instead of roll. The catalogue minimum-load formula gives the axial preload — from the machine weight, springs or a dead-weight — that keeps the contact rolling.
What should be checked before substituting another make for 51409?
The 45/100/39 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 130 kN / C0a 242 kN, the speed figures and the shaft/housing washer identification against the donor catalogue.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.