The SKF 51108 is a single - direction thrust ball bearing with a 40mm inner diameter, 60mm outer diameter, and 13mm thickness. Made of GCr15 high - carbon chromium bearing steel with a pressed steel cage, it can only bear unidirectional axial loads. It is suitable for scenarios that require low - speed and high - precision axial positioning, such as machine tool lead screw drives, automation equipment lifting mechanisms, and textile machinery spindle supports. It features a compact structure, excellent axial stiffness, and the ability to withstand certain impacts.