What are double row ball bearings? What are their advantages and disadvantages compared to single row ball bearings?

Overview of Double Row Ball Bearings
Double row ball bearings are ball bearings designed with two rows of rolling elements. This design allows the bearing to simultaneously withstand large radial loads and certain axial loads. Double row ball bearings have two separate raceways between the inner and outer rings of the bearing, each with a row of rolling elements (balls).

Advantages
Higher load carrying capacity:

The design of double row ball bearings allows them to withstand more radial loads than single row ball bearings. With two rows of rolling elements, the load is more evenly distributed and the load carrying capacity is significantly improved.
Improved stability:

The double row design provides better support and stability, especially under high load and high vibration conditions. It can reduce the impact of eccentric loads on the bearing, thereby improving the stability and reliability of the equipment.
Better alignment:

The structure of double row ball bearings can better maintain alignment and reduce eccentricity caused by inaccurate installation or uneven load.
Bidirectional axial loads:

In addition to radial loads, double-row ball bearings can also support bidirectional axial loads (i.e. loads applied in two directions), which makes them perform well in applications that require axial loads.
Disadvantages
Higher cost:

Double-row ball bearings are generally more expensive than single-row ball bearings because they are more complex to manufacture, use more material, and require more precision machining.
Larger space requirements:

Due to the larger structural dimensions of double-row ball bearings, they require more installation space when designed. This can be a limiting factor in some compact designs.
Friction and heat:

Due to the two rows of rolling elements, double-row ball bearings generally have higher friction than single-row ball bearings, which can cause more heat to be generated at high speeds.
Increased weight:

Double-row ball bearings are heavier than single-row ball bearings, which can be a disadvantage in some weight-sensitive applications.
Installation and maintenance complexity:

Due to the more complex structure of double-row ball bearings, higher precision and precautions are required during installation and maintenance to avoid unnecessary failures or damage.