NSK vs NTN Bearing Part Numbers: Field-Level Comparison

Criteria used here

1. Is the base number and boundary dimension the same?
2. Is the closure type the same (open, shield, contact seal, non-contact seal; one or both sides)?
3. Is the clearance class the same?
4. Do published load ratings and limiting speeds agree?
5. Are tolerance class, cage, grease and temperature range stated and equal?

This page does not re-explain seal codes across all brands; that is covered in is it the same bearing? and the bearing suffix reference. Here the focus is two Japanese makers, field by field.

NSK vs NTN, side by side

Field	NSK	NTN
Base number	ISO base, e.g. 6205	ISO base, e.g. 6205
Shield, both sides	ZZ (Z for one side)	ZZ (Z for one side); NTN lists ZZ as a non-contact steel shield
Contact rubber seal, both sides	DDU (DD also listed)	LLU (LU for one side)
Non-contact rubber seal, both sides	VV	LLB (LB for one side)
Low-torque seal	not retrieved	LLH
Clearance	C3, C4 and other C codes appear in part names (e.g. 6302VVC3, 6805DDC4P6)	C1 to C5 listed; blank = normal; C3 greater than normal
Precision suffix	P6, P5, P4 (ISO classes 6, 5, 4); none = ISO Class 0	not retrieved for this comparison
Product-page fields	cage, tolerance class, limiting speeds	seal material, radial clearance, temperature range, limiting speeds

NSK’s own naming covers “D, DU, DW and V (DD, DDU, DDW, VV)” for sealed bearings and “Z (ZZ)” for shielded ones, ranking sealed bearings above shielded and open bearings for sealing performance. NTN’s FAQ states that a contact LU seal gives better control of grease contamination but higher torque and a lower limiting speed than a non-contact LB seal.

Worked example 1: 6205 with contact seals

Field	NSK 6205DDU	NTN 6205LLU
Bore x OD x width	25 x 52 x 15 mm	25 x 52 x 15 mm
Closure	rubber contact seal, both sides	contact seal, nitrile rubber, both sides
Basic dynamic radial load rating	15,400 N	15,500 N
Basic static radial load rating	7,850 N	7,850 N
Limiting speed, grease	9,000 min⁻¹	8,900 min⁻¹
Radial clearance	not retrieved	CN
Cage / tolerance	pressed steel cage, ISO normal	not retrieved
Temperature range	not retrieved	-40 to 120 °C

Same size, same seal type, nearly the same ratings. Still not identical: the load and speed values differ, and cage and temperature data exist for one record only. Classification: plausible substitute. Unverified: cage, grease and tolerance on the NTN side.

Worked example 2: 6205 with shields

Field	NSK 6205ZZ	NTN 6205ZZ
Bore x OD x width	25 x 52 x 15 mm	25 x 52 x 15 mm
Closure	shield, both sides	double shielded, non-contact steel shield
Basic dynamic radial load rating	15,400 N	15.50 kN
Basic static radial load rating	7,850 N	7.85 kN on one NTN field, 11.60 kN on another (internal conflict)
Limiting speed, grease	15,000 min⁻¹	13,000 min⁻¹
Radial clearance	not retrieved	CN

The shield code is the same, but a 2,000 min⁻¹ difference in grease limiting speed and an internal static-rating conflict on the NTN page are exactly the details that a code match hides. The static rating needs a check against the NTN catalog before it is published.

Similar, different, unknown

• Similar: base number and boundary dimensions; closure family when the type matches (contact versus contact, shield versus shield).
• Different: suffix spelling (DDU versus LLU, VV versus LLB); published speed limits and, by a small margin, dynamic ratings.
• Unknown without the datasheet: cage material, grease, tolerance class on the other side, seal geometry and friction.

Realistic decision

A buyer searches NTN 6205LLU and the distributor stocks NSK 6205DDU. The sound listing says: “Same dimensions and contact-seal type; ratings and speed limit differ slightly; confirm clearance, cage and grease for your application.” It does not say “equivalent” or “identical”.

When not to auto-merge

• Closure types differ (DDU versus VV, LLU versus ZZ).
• Clearance differs or is missing on either side.
• A precision suffix (P6, P5, P4) is present on one side only.
• Either record carries a suffix you cannot decode (NSK “CM” or NTN “/2AS” style codes are not defined by the sources used here).
• Published ratings or limiting speeds conflict between sources.

Pairs that pass these checks still go in as plausible substitute with the differing values shown, not as one record. For a cross-brand pairing method see the bearing suffix reference. Decode codes with the bearing decoder. For SKF and FAG naming see SKF vs FAG designations.

Sources

Retrieved 12 October 2026; the pages do not show catalogue edition dates.

• NSK 6205DDU: 25 x 52 x 15 mm; rubber contact seal both sides; Cr 15,400 N; C0r 7,850 N; grease 9,000 min⁻¹; pressed steel cage; ISO normal.
• NSK 6205ZZ: Cr 15,400 N; C0r 7,850 N; grease 15,000 min⁻¹. NSK 6205 open variant.
• NSK deep groove ball bearings: D, DU, DW, V and Z designations; sealing ranking. NSK 6302VVC3 and 6805DDC4P6 product pages.
• NTN 6205LLU: d, D, B 25, 52, 15 mm; contact seal, nitrile rubber; 15,500 N; 7,850 N; grease 8,900 min⁻¹; CN; -40 to 120 °C.
• NTN 6205ZZ: double shielded; 15.50 kN; grease 13,000 min⁻¹; CN; static rating conflict noted above.
• NTN catalog 2203E, deep groove ball bearings: ZZ, LLB, LLH, LLU families; C1 to C5. NTN FAQ: LB versus LU seal behaviour.

Needs review: NSK clearance symbol “CM”, NTN /2AS grease suffix, the NTN 6205ZZ static rating, and NSK’s equivalent of NTN’s low-torque LLH seal.

Related

FAQ

Is NSK 6205DDU the same as NTN 6205LLU? +

They are the same size (25 x 52 x 15 mm) and both are rubber contact-sealed on both sides, but they are not shown as identical products. The published figures differ slightly: NSK lists a dynamic rating of 15,400 N and a grease limiting speed of 9,000 min-1, NTN lists 15,500 N and 8,900 min-1.

What does LLB mean on an NTN bearing? +

NTN’s catalog lists LLB as a non-contact rubber seal on both sides, as opposed to LLU, which is a contact rubber seal. NSK’s closest listed equivalent type is VV, a rubber non-contact seal, but a matching type does not make the two products identical.