Which best describes a ball thrust bearing?

• A. A type of rotary ball bearing designed to support high axial loads.
• B. A plain bearing used for sliding motion.
• C. A magnetic levitation device.
• D. A roller bearing for radial loads.

Answer: (A)

Ball thrust bearings are a type of rotary bearing that uses balls to carry load between races and is designed to support axial (along the shaft) loads. The term “thrust” specifies the direction of the load, so these bearings handle forces pushing or pulling along the axis of rotation, while allowing the shaft to rotate with relatively low friction. They’re ideal when the main stresses are along the shaft and the radial load is not dominant. In contrast, a plain bearing relies on sliding contact with no rolling elements, a magnetic levitation device uses magnetic forces to levitate components, and a roller bearing for radial loads is built to support loads perpendicular to the shaft rather than along it, so it isn’t a thrust bearing.