The transmission efficiency of automobile semi-axle is influenced by many factors, mainly including the following points:

1. Lubrication: The lubrication of the semi-axle transmission system directly affects the transmission efficiency. If the lubricating oil is insufficient or of poor quality, it will increase the friction resistance of the semi-axle transmission system and reduce the transmission efficiency.

2. State of axle bearing: The wear degree of axle bearing will affect the transmission efficiency. If the axle bearing is seriously worn or loose, it will lead to the increase of friction in the transmission system and affect the transmission efficiency.

3. Tire condition: The air pressure of the tire, the degree of wear, the contact between the tire tread and the ground and other factors will affect the transmission efficiency of the semi-axle. Uneven tire wear or insufficient tire pressure will lead to a decrease in transmission efficiency.

4. Pavement condition: The friction coefficient of different pavements is different, which will affect the transmission efficiency of the semi-axle. When the road surface is slippery, muddy or frozen, the transmission efficiency of the axle shaft may be reduced.

5. Steering angle: When the vehicle is turning, the semi-axle transmission system will be subject to certain angle changes. Excessive steering angle will increase the friction resistance of the transmission system and affect the transmission efficiency.

6. Load condition: The vehicle load condition will also affect the transmission efficiency of the semi-axle. Excessive load will increase the load of the transmission system and reduce the transmission efficiency.

To sum up, lubrication condition, axle bearing condition, tire condition, road surface condition, steering angle and load condition will all affect the transmission efficiency of automobile axle. Therefore, regular inspection and maintenance of the semi-axle transmission system, keeping good lubrication condition, semi-axle bearing condition and tire condition, choosing suitable road surface, and reasonably controlling the steering angle and load condition are all helpful to improve the semi-axle transmission efficiency and ensure the normal operation of the vehicle.