This nut secures the front axle assembly on the host tractor. It threads onto the axle spindle to retain the wheel hub and bearing stack against the steering knuckle. A loose or improperly torqued nut allows axial play in the hub, which leads to uneven tire wear and accelerated bearing failure. The manufacturer machines the thread to match the original spindle tolerance, so the nut seats fully against the washer face without cross-threading. On reinstallation, clean the threads and torque the nut to the specification for the axle assembly.