NSK 21305CDKE4 dimensions and technical reference
NSK 21305CDKE4 is a spherical roller bearing in the 21305 base-designation group. The published boundary dimensions are 25×62×17 mm: nominal bore d × outside diameter D × width B. The data below apply to this complete NSK designation, not every brand or suffix sharing 21305.
Bore, cage and suffix identification
The K marking identifies a 1:12 tapered bore. The 25 mm value is the nominal bearing bore, not the bore of an adapter sleeve or a straight-shaft fit. Confirm the mounting seat and residual clearance using the applicable instructions. The listed design uses a pressed steel cage. E4 identifies lubrication grooves and holes in the outer ring; it is not a seal suffix.
Model-specific load calculation
For Fr > 0, compare Fa/Fr with e = 0.29. At or below this threshold, P = Fr + 2.3Fa. Above it, P = 0.67Fr + 3.4Fa. The static equivalent load is P0 = Fr + 2.3Fa. Use one consistent load unit. Cr = 43 kN and C0r = 40.5 kN are calculation ratings, not permissible working loads for an unspecified machine.
Reading the speed ratings
The grease limiting speed is 5300 r/min and the oil-bath limiting speed is 6700 r/min. Thermal speed rating and forced-oil-circulation mechanical limit are separate catalogue fields; do not use the largest figure as a universal maximum. A dash means the manufacturer did not state that field, not zero speed. Operating load, lubrication and heat removal still require assessment.
Selection limits and information still required
- The unqualified catalogue designation uses CN internal clearance and ISO Normal precision according to the manufacturer’s omission rules. A C3, C4, P6 or other qualified bearing needs its own identification; the omitted suffix does not provide a numerical clearance range.
- The family accommodates angular misalignment. NSK gives an approximate family-level range of 1° to 2.5° under normal loads, depending on size and load; this is not a guaranteed angle for this individual bearing or surrounding assembly.
- Very light loading or a high axial/radial load ratio can cause roller slip and smearing. The equivalent-load formulas do not by themselves establish a safe operating condition.
- Mounting dimensions distinguish minimum and maximum shaft and housing shoulders. An unstated da maximum is not an unrestricted design approval.
- No adapter-sleeve part number, installed clearance, grease grade, CAD download or machine fitment is established by this model row. Check those separately before selecting a part.
- Mass is published once for the shared cylindrical/tapered catalogue row. It is shown as a shared reference, not a separately verified mass for this tapered variant.
Technical basis:NSK Rolling Bearings for Industrial Machinery, E1103d (2025), Part C, C266–C267; designation rules and family limitations C258–C259. Source checked 2026-10-01. Independently organised reference data, not a sales offer or an interchange approval.
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