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Product Series of Automation-Related Precision Ball Screws and Linear Rails – High-Precision Ball Screws

NSK Bearings Spherical Roller Bearings 21304

Product Overview

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Spherical Roller Bearings/Bearings

21304

Spherical Roller Bearing

NSK Distributor Taiwan

Bore d20 mm
Width B15 mm

Product Features

NSK spherical roller bearing (21304 series), model 21304: 20 mm bore, 52 mm OD, 15 mm width, cylindrical bore (no K)
Basic dynamic load rating Cr 29.3 kN, basic static load rating C0r 26.9 kN (NSK official catalog; current-generation equivalent 21304CDE4, Cr/C0r figures above are taken from that higher-capacity current design)
Thermal speed rating approx. 10000 min⁻¹, limiting speed (grease) approx. 6300 min⁻¹
Double-row rollers on a spherical outer raceway self-align for misalignment and shaft deflection — suited to long shafts and heavy-duty drives
Nahshon is NSK's distributor in Taiwan — add the part number to your inquiry list

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Product Description

The 21304 is an NSK spherical roller bearing from the 21304 series: 20 mm bore, 52 mm outer diameter, 15 mm width, cylindrical bore (no K). Basic dynamic load rating Cr is 29.3 kN and basic static load rating C0r is 26.9 kN (NSK official catalog CAT. No. E1103d; current-generation equivalent 21304CDE4, Cr/C0r figures above are taken from that higher-capacity current design). Spherical roller bearings use double-row rollers on a spherical outer raceway that self-aligns for misalignment and shaft deflection while carrying heavy radial and bidirectional axial loads — common in gear reducers, conveyor rollers, paper machinery and wind-turbine main shafts.

Inquiries & customization

Add this part number to your inquiry list — Nahshon is NSK's distributor in Taiwan and works directly with the factory to confirm specifications, stock and pricing.

Product Specifications

Specification	Unit	21304
Series	-	21304 series
Bore d	mm	20
Outer diameter D	mm	52
Width B	mm	15
Min. chamfer r	mm	1.1
Bore type	-	cylindrical bore (no K)
Basic dynamic load rating Cr	kN	29.3
Basic static load rating C0r	kN	26.9
Thermal speed rating	min⁻¹	10000
Limiting speed (grease)	min⁻¹	6300

FAQ

What's the difference between the Z, ZZ and DDU suffixes?

Z means a single-side steel shield, ZZ means steel shields on both sides, and DDU means contact rubber seals on both sides. Shields suit general environments and high speeds; rubber seals give better dust and water protection with slightly higher friction torque — choose based on your dust exposure and lubrication method.

When should I choose C3 clearance instead of standard clearance?

For motors or other applications with noticeable temperature rise, or high-speed operation, the inner ring expands from heat and reduces the clearance — choose C3 in that case. Standard clearance is fine for general room-temperature, low-speed use. See Nahshon's technical resources for a clearance selection guide.

Is 21304 in stock in Taiwan? What is the lead time?

Nahshon is the NSK distributor in Taiwan and keeps stock of some commonly used items. Add 21304 to your inquiry list or give us a call, and we'll confirm stock, lead time and quote.

Series Models

Spherical Roller Bearings・21304 series

21304（This page）21305 21306 21306K 21307 21307K 21308 21308K 21309 21309K 21310

View All Spherical Roller Bearings Models →