The four main types of bearings are ball bearings, roller bearings, plain bearings, and thrust bearings. Each type is designed to address specific load-bearing requirements and operational conditions in various machines and equipment across different industries.

The deep groove in a ball bearing is characterized by a raceway with a deep, concave profile that forms a continuous, circular track for the bearing's rolling elements, typically steel balls. This design feature allows the balls to move freely within the raceway, distributing the load evenly and minimizing friction during rotation. The deep groove also provides space for the lubricant, which helps to reduce wear and heat generation, ensuring the bearing's longevity and reliability.