The SKF 51109 is a single-direction thrust ball bearing with a 45mm inner diameter, 65mm outer diameter, and 14mm thickness. Made of GCr15 high-carbon chromium steel with a pressed steel cage, it withstands unidirectional axial loads only. Ideal for low-speed, high-precision axial positioning applications (e.g., large machine tool lead screws, heavy machinery axial supports, mining equipment adjustment mechanisms), it offers a compact design, high axial rigidity, and resistance to heavy impacts.