This toothed lock washer secures the threshing drive assembly on the host machine. It sits between the rotating component and the retaining nut, using its internal teeth to grip the shaft and prevent the nut from backing off under vibration or load. A loose or missing washer allows the drive component to shift, which can lead to misalignment and accelerated wear on the mating splines. On reinstallation, ensure the washer is seated fully against the shoulder and that the nut is torqued to the specification for the assembly.