Maybe the seal is aging. Seals are usually used to prevent lubricating oil from leaking from the joint of the transmission shaft, but if the seals are worn, hardened or aged, it will lead to oil leakage. Wear of mechanical parts may also lead to oil leakage of tractor front axle transmission shaft. Long-term use will lead to the wear and tear of mechanical parts, such as bearings, gears and seals of transmission shafts. When these parts are worn to a certain extent, oil leakage will occur.