Double-row Deep Groove Ball Bearings

The double-row deep groove ball bearing is a type of rolling bearing that compensates for the insufficient bearing capacity of single-row deep groove ball bearings and is widely used. Its structure features an uninterrupted deep raceway, and it is often equipped with a glass fiber reinforced nylon 66 cage that can operate at a temperature of 120°C. In terms of performance, it can withstand radial loads and bidirectional axial loads. The radial load capacity is approximately 1.62 times that of a single-row deep groove ball bearing, with a relatively high limit speed. However, the inner and outer rings must be concentric, and the allowable angle error is only 2 arc minutes. Common models include 4200A, 4300A, and domestic models such as 63308-2Z/YA and 63209-2Z/YA, with inner diameters ranging from 10 to 305mm. Different models correspond to different outer diameters, widths, and rated loads. For example, the 4204ATN9 bearing has an inner diameter of 20mm and an outer diameter of 47mm, with a basic rated dynamic load of 17.8kN. This bearing is suitable for equipment requiring high load-bearing capacity such as electric motors, household appliances, precision instruments, machine tools, agricultural machinery, textile machinery, etc. When using it, it is necessary to bear a certain minimum load to prevent harmful sliding movement, and the pure axial load should generally not exceed 0.5 times the basic rated static load (C0) to avoid significantly shortening the bearing's service life.

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Product Introduction

Double-row deep groove ball bearings are rolling bearings upgraded from single-row deep groove ball bearings. Through structural optimization of double-row raceways and rolling elements, they make up for the insufficient load-carrying capacity of single-row bearings. With the characteristics of balancing load-carrying capacity and stability, they are widely used in various medium and high-load working conditions. The following details their core structure, key performance, specifications & models, application scenarios, and usage guidelines.

1. Core Structural Features

Double-row deep groove ball bearings share a similar design with single-row deep groove ball bearings, with the core difference lying in structural enhancement brought by the double-row configuration. Specific features are as follows:

Raceway Design: Adopts continuous double-row deep arc raceways. The raceways and steel balls have extremely high fit, which provides a stable movement path for rolling elements and ensures smooth operation.

Cage Configuration: Standardly equipped with two glass fiber-reinforced nylon 66 cages (e.g., SKF bearings marked with suffix "TN9"). This type of cage has good temperature resistance, enabling stable operation at temperatures up to 120°C, and is not affected by conventional bearing lubricants (except for special synthetic oils or lubricants containing a large amount of extreme pressure additives).

Structural Stability: The symmetrical double-row layout makes the bearing bear loads more evenly. Compared with single-row bearings, it is less prone to deformation, resulting in significantly improved structural stability.

2. Key Performance Parameters

The performance advantages of double-row deep groove ball bearings focus on load-carrying capacity and operational stability, while having clear requirements for installation accuracy. The core parameters are shown in the table below:

Performance Indicator	Specific Description
Load-Carrying Capacity	The radial load-carrying capacity is approximately 1.62 times that of single-row deep groove ball bearings of the same specification, and it can withstand bidirectional axial loads.
Limiting Speed	It has excellent speed performance. For example, the 4200ATN9 model (bore diameter: 10mm, outer diameter: 30mm) has a limiting speed of up to 22,000 r/min.
Alignment Accuracy Requirement	The allowable angular error is only 2 arcminutes. Exceeding this range will cause increased noise, additional loads, and shortened service life.
Temperature Adaptation Range	When equipped with a nylon cage, the upper limit of the applicable temperature is 120°C.
Internal Clearance	Standard models adopt ordinary group radial internal clearance; other clearance groups can be selected according to requirements.

3. Typical Models & Specification Examples

The model system of double-row deep groove ball bearings is clear. Common standard models include the 4200A and 4300A series, while domestic models such as 63308-2Z/YA are also available. The bore diameter ranges from 10mm to 305mm, and different models correspond to differentiated dimensions and load parameters. The table below shows specifications of some typical models:

Model	Bore Diameter (mm)	Outer Diameter (mm)	Width (mm)	Basic Dynamic Load Rating (kN)	Basic Static Load Rating (kN)	Application Reference
4200ATN9	10	30	14	9.8	5.2	Small precision instruments
4204ATN9	20	47	18	17.8	12.5	Household appliance spindles
4306ATN9	30	72	27	38.5	27.2	Machine tool auxiliary components
63308-2Z/YA	40	90	33	55.0	40.8	Conveyor drive systems

4. Application Fields & Selection Comparison

Double-row deep groove ball bearings are mainly used in scenarios where single-row bearings cannot meet load requirements. The selection differences between double-row and single-row deep groove ball bearings can be quickly distinguished through the table below:

Comparison Dimension	Double-Row Deep Groove Ball Bearings	Single-Row Deep Groove Ball Bearings
Load-Carrying Capacity	Strong, suitable for medium and high-load working conditions	Weak, only suitable for low-load working conditions
Operating Speed	Medium to high speed (heat dissipation measures are required for high speed)	High speed, low frictional heat generation
Structural Complexity	Relatively high, larger width	Simple, low manufacturing cost
Installation & Maintenance	High alignment requirements; installation accuracy affects service life	Easy to install, low maintenance difficulty
Typical Application Fields	Heavy machinery, automotive components, machine tools, agricultural/textile machinery	Household appliances, office equipment, small fans

5. Usage Precautions

Minimum Load Requirement: A certain minimum load must be applied, especially under working conditions of high speed, high acceleration, or frequent changes in load direction. If the natural load is insufficient, additional radial load should be applied to avoid harmful sliding between balls and raceways.

Axial Load Limit: When bearing pure axial load, the load shall not exceed 50% of the basic static load rating (C0); otherwise, the service life will be significantly shortened.

Lubrication & Temperature: Avoid using incompatible lubricants (such as synthetic oils with special extreme pressure additives). For low-temperature startup or when the grease viscosity is too high, the minimum load requirement needs to be increased.

Installation Accuracy: Strictly control the installation alignment error to ensure that the angular deviation does not exceed 2 arcminutes, so as to reduce additional loads and operating noise.

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