This simering is a lip seal that retains lubricant in the front axle housing while excluding dirt and moisture. It sits at the shaft exit point of the axle assembly, where the rotating shaft passes through the stationary housing. A worn or hardened lip allows lubricant to weep past the seal, leading to a gradual loss of axle oil and potential contamination of the bearing surfaces. The seal is manufactured to the original housing bore tolerance and shaft contact geometry, so it seats correctly without additional shimming or modification. On installation, inspect the shaft surface for grooving or pitting; a damaged shaft should be repaired or sleeved before fitting the new seal.