NNU49-500K bearing: complete specifications & equivalents
The NNU49-500K is a ISO 15 radial bearing sized 500 x 670 x 170 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 500 mm |
| Outer diameter D | 670 mm |
| Width B | 170 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 2670 kN |
| Basic static load rating C0 | 6400 kN |
| Fatigue load limit Pu | 455 kN |
| Limiting speed (mechanical) | 730 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 155000 g |
| Manufacturer designation | NTN NNU49/500K |
| Standard | ISO 15 |
| 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 & NNU50000-series range
| Bore d | 19.685 in |
|---|---|
| Outer diameter D | 26.378 in |
| Width B | 6.693 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 85 mm |
| Smallest bore in NNU50000-series | 500 mm |
| Largest outer diameter in NNU50000-series | 670 mm |
| Width range across NNU50000-series | 170–170 mm |
| Bore position in NNU50000-series (smallest first) | 1 of 1 |
| Bore above smallest NNU50000-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU49 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the 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 NNU49-500K model number is decoded
NNU49/500K is an NTN NNU cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 500×670×170 mm ISO 15 envelope. Numbering ties NNU49/500K to its envelope: type code NNU, series NNU50000, 500 mm bore; the 670×170 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. Line contact between rollers and raceways gives NNU49/500K high radial capacity but no tolerance for misalignment: beyond roughly 3–4 arc-minutes the roller ends edge-load and fatigue accelerates. Thermal planning around the 730 r/min grease ceiling should include the cage type (a machined or stamped steel cage per the precision execution) and oil-flow option to 860 r/min for continuously high-duty 500 mm positions. Housing and shaft fillets must clear the ring chamfers of NNU49/500K; an oversized radius locks the ring on its face and tilts the 170 mm-wide seat.
Typical equipment & failure modes
Common applications
- precision gearbox and indexing-drive shafts
- high-rpm motorised grinding and milling spindles
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 500 mm bore, oil-lubricated arrangements toward 860 r/min need positive flow and drain design; the 155000 g NNU49/500K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 500 mm bore share bore but not OD/width; check the full NNU50000 series code before substituting, because housing and shoulder geometry will not interchange.
- The NNU rib arrangement is not interchangeable with another prefix on the same 500 mm seat: double row, ribbed outer ring, separable inner. Swapping NU for NJ changes axial location behaviour even though the 670×170 mm envelope matches.
- The NNU rib arrangement is not interchangeable with another prefix on the same 500 mm seat: double row, ribbed outer ring, separable inner. Swapping NU for NJ changes axial location behaviour even though the 670×170 mm envelope matches.
- Wide (22/23) and light (10/49) executions at 500 mm bore share bore but not OD/width; check the full NNU50000 series code before substituting, because housing and shoulder geometry will not interchange.
- The 2670/6400 kN ratings, 455 kN Pu and 155000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU49/500K (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.
Frequently asked questions
What are the dimensions and catalogue data of NNU49/500K?
NNU49/500K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 500 mm bore, 670 mm OD and 170 mm width (19.685 × 26.378 × 6.693 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 2670 kN, C0 6400 kN, Pu 455 kN, grease limiting speed 730 r/min, oil 860 r/min, mass about 155000 g. It is open, with a machined or stamped steel cage per the precision execution.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
NN and NNU are double-row precision designs rather than single-row rib variants: NN has a ribbed inner ring and separable outer ring, NNU the reverse; both give high radial stiffness for spindles and are commonly ordered with P5/P4 precision and a K 1:12 tapered bore for preload setting. NNU49/500K is the NNU execution.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. NNU49/500K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU49/500K?
The K suffix denotes a 1:12 tapered bore. NNU49/500K mounts on a tapered shaft seat or adapter sleeve and is driven up to a measured residual clearance or preload — this is how precision spindle bearings achieve stiffness without locknut guesswork; the cylindrical-bore NNU49/500 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU49/500K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 556 mm. The nominal bore/OD remain 500/670 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 730 r/min grease / 860 r/min oil.
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.