Double Row Cylindrical Roller Bearings Nnu4928/W33 Nnu4930/W33 Nnu4932/W33 Nnu4934/W33 Nnu4936/W33 Nnu4938/W33 Nnu4940/W33 Nnu4944/W33 Nnu4948/W33

• Customization: Available
• Rolling Body: Roller Bearings
• The Number of Rows: Single
• Model NO.: NNU4928/W33 NNU4930/W33 NNU4932/W33 NNU4934/W3
• Outer Dimension: Medium and Large(120-190mm)
• Material: Bearing Steel, Chrome Steel Gcr15
• Spherical: Aligning Bearings
• Load Direction: Radial Bearing
• Separated: Unseparated
• Vibration: Zv1 Zv2 Zv3
• Hardness: HRC60--62
• Cage: Steel Nylon Brass
• Service: OEM
• Grease: Sheel Great Wall
• Precision: P0 P6 P5
• Package: Industry or Single Box
• Transport Package: Industry or Single Box
• Specification: Standard
• Trademark: UJK
• Origin: China
• HS Code: 84821020
• Production Capacity: 100000

Product Description

 

Product Description

 

 

    

Product Overview: UJK Double-Row Cylindrical Roller Bearing

Precision Radial Load Solutions for Rigid Shaft Guidance
The UJK Double-Row Cylindrical Roller Bearing delivers exceptional radial load capacity and rigidity in compact designs. Engineered for precision applications requiring minimal axial space and maximum rotational accuracy, these bearings feature optimized roller profiles and premium materials for superior performance in high-speed, high-load industrial environments.

 

Key Features & Benefits

 Ultra-High Radial Load Capacity

• Two rows of precision-ground cylindrical rollers

• 30-40% higher radial load rating vs. single-row designs

 Precision Running Accuracy

• UJK-grade tolerances (ISO P6/P5 classes available)

• Minimal radial runout (±0.005 mm typical)

 Space-Saving Design

• Compact width vs. two single-row bearings

• Integrated rib guidance for axial positioning

 UJK Performance Enhancements

• Nitrided steel cages for high-speed stability (up to 5,000 rpm)

• Super-finished raceways reduce friction and noise

• High-purity chromium steel (HRC 60-64 hardness)

 

Model & Dimension Specifications (Typical UJK Series)

Model	d (mm)	D (mm)	B (mm)	Dynamic Load (kN)	Static Load (kN)	Speed Limit (rpm)
UJK NN3008	40	68	38	110	125	8,000
UJK NN3016	80	125	48	250	300	6,300
UJK NN3030	150	225	72	650	780	4,000
UJK NNU4940	200	280	85	900	1,100	3,800
UJK NNU4968	340	460	140	2,400	2,900	2,400

Notes:
d = Bore Diameter • D = Outer Diameter • B = Width
NN = Double-row with inner ring ribs • NNU = Double-row with outer ring ribs

 

Design Variations & Suffixes

Suffix	Feature	Technical Impact
K	Tapered bore (1:12)	Adapter sleeve mounting
P4	Ultra-precision grade	≤ 50% runout of P5 class
M	Brass cage	High-speed capability (↑30% rpm limit)
C3	Increased radial clearance	Thermal expansion compensation
W33	Lubrication groove + holes	Forced oil systems
S1	Stabilized heat treatment	≤ +200°C operating temp

 

Technical Highlights

 Internal Design Options:

• NN Design: Ribs on inner ring (outer ring separable)

• NNU Design: Ribs on outer ring (inner ring separable)

• Full complement rollers: For extreme radial loads (suffix V)

 Mounting Criticals:

• Requires precise alignment (no self-aligning capability)

• Housing bore tolerance: H7/J7

• Shaft tolerance: k5/m6

 Lubrication Systems:

• Oil mist: Recommended for >4,000 rpm

• Grease: Lithium complex (NLGI 2) with relubrication ports

 

Typical Applications

• Machine tool spindles: Lathe heads, grinding wheel shafts

• Gearbox support bearings: Wind turbine gear stages

• Rolling mill backup rolls: Precision strip processing

• Printing machinery: Impression cylinder journals

• Medical equipment: MRI gantry rotation systems

 

Why Choose UJK Double-Row Cylindrical Rollers?

*"UJK bearings achieve 40% higher rigidity than competitive designs through:
• Optimized logarithmic roller profiles
• Raceway crowning ≤ 0.002xD
• Cage-guided roller alignment
Resulting in 3-5 dB noise reduction and 20% longer service life in precision spindle applications."*