Wheel axles. The driving bevel gear of the drive axle is one of the important parts of the drive axle that must be equipped for longitudinal vehicles with engines. It belongs to the shaft category and is a wheel shaft. It is composed of a conical tooth part, a shaft diameter for installing bearings, a splined shaft for connecting transmission, and external threads. It is an important transmission gear that transmits the power of the engine to the driving wheels. Due to the continuous rotation of the driving gear and the driven gear, the oil is constantly pressed to the desired position. According to the structure, the oil pump can include gear type and rotor type. Gear oil pump has external gear type and internal gear type. The driving gear and driven gear are installed in the oil pump housing of the external gear engine. The distance between the gear and the inner wall of the housing is very small, and there is an oil inlet on the housing. When the gear rotates, due to the movement of the gear teeth in the direction of detachment, the volume of the oil inlet chamber increases, and the necessary vacuum is generated in the chamber. Oil is sucked out of the oil inlet and filled into the oil inlet chamber. When the gear rotates, the oil stored between the teeth is brought into the oil outlet chamber. Due to the meshing of gear teeth on one side of the oil outlet chamber, the volume of the oil outlet chamber decreases, and the oil pressure increases. The oil is sent into the oil circuit of the starting engine through the oil outlet.