Two-stage pit transmission shaft front spline shaft capable of improving part strength and reducing weight

The front spline shaft mainly comprises a first-stage pit, a second-stage pit and the like, the first-stage pit and the second-stage pit are machined in the front end of a shaft body, the second-stage pit is located at the bottom of the first-stage pit, a spigot is formed in the outer side of the front end of the shaft body, and the spigot is located at the bottom of the second-stage pit. A bearing guard and a spline are arranged outside the middle of the shaft body, a fillet is arranged at the transition position of the bearing guard and the front end of the shaft body, and a threaded guard is arranged at the tail of the shaft body. According to the front spline shaft, the pit structure is optimized, a two-stage pit design method is adopted, the wall thickness of the bearing retainer is increased, the strength of the front spline shaft is improved, a heat affected zone is effectively prevented from penetrating through the whole wall thickness during quenching, adverse effects on the fatigue performance of pa