What are the differences between DU and DAC wheel bearings?

The core differences between DU (double row tapered roller bearing unit) and DAC (double row angular contact ball bearing unit) hub bearings lie in their structural design, load-bearing capacity, and application scenarios: DU adopts a tapered roller structure, which has a stronger load-bearing capacity but a lower speed; DAC adopts a ball structure, which is suitable for high-speed and light-load scenarios and can withstand bidirectional axial loads.

1. Structural Design Differences

• DU Bearings: Composed of double-row tapered rollers, with the rollers making line contact with the raceways. They offer high structural rigidity but also have relatively high frictional resistance.

• DAC Bearings: Employ a double-row angular contact ball design, with the balls making point contact with the raceways. The contact angle is typically 30 degrees, resulting in a smaller footprint and lower frictional resistance.

2. Load Capacity Comparison

• Radial Load: Due to its tapered roller structure, the DU bearing has a significantly higher radial load capacity than the DAC bearing, making it suitable for heavy-duty applications.

• Axial Load: The DAC bearing can withstand bidirectional axial loads, limiting bidirectional shaft displacement; while the DU bearing can withstand axial loads, its primary load is radial.

3. Speed and Rigidity:

• DAC bearings, due to their spherical design, are suitable for high-speed rotation (e.g., front wheels of passenger cars) and can withstand overturning moments.

• DU bearings, due to their higher friction, are suitable for low-to-medium speed applications (e.g., rear wheels of trucks), offering higher rigidity but a lower limiting speed.

4. Typical Applications:

• DAC bearings: Commonly used in applications with high space and speed requirements, such as front wheel hubs of passenger cars and precision machinery, providing smooth rotation and low noise.

• DU bearings: Primarily used in heavy-duty or impact-load environments, such as rear wheels of commercial vehicles and industrial equipment, emphasizing durability and load-bearing strength.

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