51214 bearing: complete specifications & equivalents
The 51214 is a ISO 104 radial bearing sized 70 x 105 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 70 mm |
| Outer diameter D | 105 mm |
| Width B | 27 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Basic dynamic load rating C | 76 kN |
| Basic static load rating C0 | 199 kN |
| Fatigue load limit Pu | 8.95 kN |
| Limiting speed (mechanical) | 1800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 793 g |
| Manufacturer designation | NTN 51214 |
| 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 & 51200-series range
| Bore d | 2.756 in |
|---|---|
| Outer diameter D | 4.134 in |
| Width B | 1.063 in |
| ISO bore code | 14 |
| Radial section height (D−d)/2 | 17.5 mm |
| Smallest bore in 51200-series | 10 mm |
| Largest outer diameter in 51200-series | 520 mm |
| Width range across 51200-series | 11–112 mm |
| Bore position in 51200-series (smallest first) | 15 of 39 |
| Bore above smallest 51200-series size | 60 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 51214-SKF | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 70×105×27 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 51214 model number is decoded
51214 is the 70 mm member of NTN's medium-section 51200 thrust family: 105 mm across the washers, 27 mm tall. The designation is 512 is the dimension series (medium-section 51200 thrust family) plus 14 encodes the 70 mm bore (bore code x 5). Because the contact points run at 90 deg to the shaft, none of the rating is available for radial load — not even incidentally. For a 70 mm shaft with combined radial-plus-axial load, pair this bearing with a separate radial bearing — the thrust ball bearing must never be asked to carry the radial share. Keep the support faces square: a housing face out of perpendicular by a few hundredths over the 105 mm OD already tilts the raceway and concentrates the 199 kN static capacity on a few balls.
Typical equipment & failure modes
Common applications
- ship winch and capstan thrust shafts
- crusher main-shaft thrust supports
- large rotary-table and index-table thrust rings
- vertical water-pump and turbine thrust blocks
Known failure patterns
- ball and raceway smearing from gyroscopic spin when the bearing runs fast under too little axial load — the minimum-load rule exists exactly for this
- 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
- early fatigue from thrust reversal hammering the unloaded raceway, because the bearing has no contact surfaces for the opposite direction
- washer face corrosion under long standstill in humid service, later printed into the raceway as evenly spaced pitting
- contamination pitting from particles settling on the horizontal housing washer — the classic failure of vertical-shaft grease-lubricated seats
Selection pitfalls — read before you substitute
- At 70 mm bore the washers are heavy enough to sag out of square during assembly — support the stack horizontally where possible and verify face runout before loading.
- The 512 medium section is the default choice: balanced height and capacity for general vertical-shaft duty at 70 mm bore.
- Single-direction means exactly that: thrust on 51214 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- A housing washer pressed tight in its seat cannot self-centre; the resulting eccentric running shows up as cage wear long before raceway fatigue.
- Single-direction means exactly that: thrust on 51214 in the wrong direction separates the washers and drops the ball set — if reversal is possible even during coast-down, engineer against it.
- The Ca 76/C0a 199 kN ratings and 8.95 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 51214; 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 51214?
51214 is a single-direction thrust ball bearing to ISO 104: 70 mm shaft-washer bore, 105 mm outside diameter, 27 mm stack height (2.756 x 4.134 x 1.063 in). From NTN Ball and Roller Bearings CAT.No.2203E: axial Ca 76 kN, C0a 199 kN and a 8.95 kN fatigue load limit Pu; the grease limiting speed is 1,800 r/min and the oil rating 2,600 r/min; mass about 793 g.
How is the 51214 designation structured?
512 is the dimension series (medium-section 51200 thrust family); 14 encodes the 70 mm bore (bore code x 5). The 105 mm OD and 27 mm height follow the ISO 104 boundary plan for that series.
Can 51214 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 51214?
At the 1,800 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 51214?
The 70/105/27 mm envelope is ISO 104 interchangeable, but washer bore codes, raceway osculation and ratings are maker-specific. Re-verify Ca 76 kN / C0a 199 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.