A ball bearing is a ball bearing type bearing that uses balls to maintain the distance between roller bearings. The purpose of a ball bearing is to reduce rolling friction and support radial and axial loads. It does this by using at least two shapes to hold the balls and transmit the loads through the balls. In most applications, one slot is fixed and the other is attached to the rotating assembly. When one of the bearings rotates, it causes the balls to rotate as well. Because the balls roll, they have a much lower coefficient of friction than when two flat surfaces slide against each other. Ball bearings tend to have a lower load capacity than other types of bearings for their size, due to the smaller contact area between balls and seats.

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