Bearing Basics, Types, and Classification

What Is a Bearing?

A bearing is a machine element used to locate, support, and guide the relative motion between a shaft and other components.
Its primary functions are to:

• Reduce friction

• Support radial and/or axial loads

• Ensure accurate positioning of rotating parts

• Improve efficiency and service life of mechanical systems

At DSBR Bearings, this definition is not only theoretical. It is the starting point of how bearings are designed, manufactured, and tested for real working conditions.

Bearings are widely used in automotive systems, industrial machinery, mining equipment, gearboxes, electric motors, and heavy-duty applications, where reliability and service life are critical.

Types of Bearings

Bearings are generally classified into two main categories:

Rolling Bearings

A rolling bearing is a bearing in which rolling elements move between load-carrying parts.
It consists of bearing rings with raceways and rolling element assemblies, with or without cages or guiding elements.

Rolling bearings can support:

• Radial loads

• Axial loads

• Combined radial and axial loads

Basic Components of a Rolling Bearing

A typical rolling bearing consists of four main parts:

1. Outer ring

2. Inner ring

3. Rolling elements (balls or rollers)

4. Cage (retainer)

These components work together to provide low-friction, stable, and reliable motion.

Plain Bearings (Sliding Bearings)

A plain bearing operates solely under sliding friction, without rolling elements.
They are commonly used in applications with:

• Very heavy loads

• Low speeds

• Oscillating motion

Classification of Rolling Bearings by Structure

Classification by Load Direction or Nominal Contact Angle

Nominal contact angle:
The angle between the normal line at the contact point between the rolling element and raceway, and a plane perpendicular to the bearing axis.

(1) Radial Bearings

Radial bearings are mainly designed to carry radial loads.
Their nominal contact angle ranges from 0° to 45°.

They are further divided into:

1) Radial contact bearings

• Nominal contact angle: 0°

2) Angular contact radial bearings

• Nominal contact angle: 0°–45°

(2) Thrust Bearings

Thrust bearings are mainly designed to carry axial loads.
Their nominal contact angle ranges from 45° to 90°.

They include:

1) Axial contact bearings

• Nominal contact angle: 90°

2) Angular contact thrust bearings

• Nominal contact angle: greater than 45° but less than 90°

Classification by Type of Rolling Element

(1) Ball Bearings

Rolling elements are balls.

Ball bearings include:

• Deep groove ball bearings (α = 0°)

• Self-aligning ball bearings

• Angular contact ball bearings (0° < α < 45°)

(2) Roller Bearings

Rolling elements are rollers.

Roller bearings include:

1. Cylindrical roller bearings

2. Needle roller bearings

3. Tapered roller bearings

4. Spherical roller bearings

Classification by Self-Aligning Capability

1) Self-aligning bearings

• Feature spherical raceways

• Can accommodate shaft misalignment and angular deviation

2) Non-self-aligning bearings (rigid bearings)

• Cannot compensate for misalignment

Classification by Number of Rolling Element Rows

1) Single-row bearings

• One row of rolling elements

2) Double-row bearings

• Two rows of rolling elements

3) Multi-row bearings

• Three or more rows (e.g., three-row or four-row bearings)

Classification by Separability of Components

1) Separable bearings

• Bearing components can be mounted or dismounted separately

2) Non-separable bearings

• Bearing rings cannot be separated freely after assembly

Additional Structural Variations

Bearings may also differ by structural features such as:

• Presence or absence of filling slots

• Inner ring or outer ring flanges

• Ring shapes

• Flange structures

• Presence or absence of cages

These variations result in many specialized bearing designs.

Composite Bearings and Bearing Units

Composite Bearings

A composite bearing is formed by combining different types of bearings to meet special operating requirements.

Bearing Units

A bearing unit is a functional assembly that uses a bearing as the core component and integrates other functional parts, such as:

• Housings

• Seals

• Mounting elements

Bearing units simplify installation and improve reliability.

Classification of Rolling Bearings by Size

Based on nominal outer diameter, rolling bearings are classified as:

1. Miniature bearings: ≤ 26 mm

2. Small bearings: 28–55 mm

3. Medium-small bearings: 60–115 mm

4. Medium-large bearings: 120–190 mm

5. Large bearings: 200–430 mm

6. Extra-large bearings: ≥ 440 mm

Bearing Type Codes (Examples)

Why Proper Bearing Selection Matters

Choosing the right bearing is critical for:

• Load capacity

• Service life

• Noise and vibration performance

• Maintenance cost

• Overall system reliability

Understanding bearing structure, classification, and operating principles allows engineers and buyers to select bearings that match real working conditions, rather than relying on price alone.

Understanding bearing structure and classification allows engineers to select specific components, such as a 7805 bearing, that match real working conditions rather than relying on price alone.

Conclusion

Rolling bearings are essential components in modern mechanical systems.
Understanding bearing structure, classification, and application principles is key to achieving long-term performance and reliability.

As a professional auto bearings manufacturer, DSBR Bearings combines manufacturing expertise, strict quality control, and application-oriented engineering to support customers worldwide.

Whether for heavy-duty industrial use or precision automotive applications, the goal remains the same:
reliable performance, consistent quality, and long service life.