The OK load or the Timken OK load describes the load-carrying capacity of a lubricant. The OK load is measured in a standard test (ASTM D 2509). In this test, a bearing ring rotates against a stationary steel block under an applied load. The OK load is the maximum load that can be applied without scuffing or seizure of the steel block. It is used to characterize the extreme pressure performance of greases and lubricants. The name of this test refers to the Timken Company, which developed this machine.