This Handbook is the first attempt to collect wear data which can be used in machinery design and maintenance. To some degree this objective has been achieved; however, continuing efforts are needed to fully attain the goal. Contents include: Classification of Wear Processes, Systems Approach to Wear Problems, Wear Theory and Mechanisms, Lubricated Wear, Wear Resistant Materials, Wear Coefficients of Hard-Surfacing Materials, Filtration for Wear Control, Bushings, Unlubricated Piston Rings, Gear Wear, Cutting Tool Wear, Wear in Tillage Tools, Wear in Ore Processing Machinery and Impact Wear Analysis and Applications.