How Important is a Truck Rearview Mirror?

Truck rearview mirrors all have a main rearview mirror and a wide-angle rearview mirror. Usually, the main rearview mirror has a larger area (commonly known as the large mirror) located above it, and its usage rate is the highest. It is mainly used to observe the situation on both sides of the vehicle during driving; The wide-angle rearview mirror, commonly known as a small mirror, is located below and has a larger curvature to provide a wider viewing angle. It is mainly used to compensate for the lack of perspective in the main rearview mirror and is usually used for reversing and parking. Due to the large blind spot of trucks, the requirements for rear view are very strict.

Usually, the main rearview mirror is on the top and the wide-angle rearview mirror is on the bottom.

The performance design of the rearview mirror should meet the following requirements: 

1. Ensure that the rearview field meets regulatory requirements. In addition, in order to prevent collision accidents in blind spots during reversing and parking, many trucks have installed a 360 degree panoramic view for blind spot repair

2. The rearview mirror itself should not be too large, and the A-pillar and rearview mirror should not be connected together, otherwise there will be a large blind spot during the turning process

3. The distance between the rearview mirror and the A-pillar of the vehicle needs to be accurately controlled. If the distance is too small, the canyon effect between the rearview mirror and the A-pillar of the vehicle will cause significant wind noise, similar to whistling. If the distance is too large, it will affect the vehicle's passability and cause rearview mirror collisions when passing or overtaking on narrow roads

4. The rearview mirror bracket should have sufficient stiffness to prevent resonance under various working conditions (idle, gravel road, etc.), which may ultimately cause fatigue fracture

5. Streamline reduces wind resistance. According to statistics, although the area of the rearview mirror is small, its position protrudes outside the vehicle body and forms a canyon effect with the A-pillar, which can generate 7% -9% air resistance. In order to reduce wind resistance, many heavy-duty trucks in Europe have removed physical rearview mirrors and adopted electronic rearview mirrors.

Of course, the current cost is relatively high, and it is only a high-end option for certain models, which has not been fully promoted yet.

In terms of the arrangement of mirrors, the vast majority of car models have the main rearview mirror above. However, there are several models that are very "unconventional", such as the Scania brand from Europe, where the main rearview mirror of the entire series of products is located below; The main rearview mirror of FAW Jiefang J6E and China Heavy Truck's Haowo MAX is also designed below. Many cardholders are very curious, what are the benefits of the "big mirror" design below?

Firstly, reduce wind resistance. Traditional rearview mirrors are arranged vertically when viewed from the side. If the wide-angle rearview mirror is arranged above, it can be tilted at an angle of about 20 degrees to reduce wind resistance. According to CFD calculations, the vehicle's wind resistance can be reduced by about 1.2%; When driving at a speed of 90km/h for a 49 ton heavy-duty truck, 30% of the engine's power overcomes wind resistance, which can reduce fuel consumption by 0.36% after conversion.

Secondly, The wide-angle rearview mirror provides a wider field of view. Due to the placement of the wide-angle rearview mirror above and the tilt design, the wide-angle rearview mirror occupies the commanding position, resulting in a wider field of view than traditional arrangements.

Thirdly, how to avoid the disadvantage of the main rearview mirror being located below. Due to the small angle of the seat back of a flathead truck, the driver usually only has slight contact with the backrest on the back, and the position of the eyes is exactly aligned with the traditional arrangement of the main rearview mirror. Therefore, when turning to look at the main rearview mirror, the driver does not need to lower their head. After the main rearview mirror is arranged below, if the original sitting position is still maintained, the driver needs to slightly lower their head when turning to look at the rearview mirror. The above three models are all long-distance trunk logistics models. To avoid this problem, all three models have increased the seat back angle and steering wheel adjustment angle, making the driver sit in a similar position to a passenger car, improving the driver's comfort. At this point, the driver's head position will slightly lower compared to before, and there is no need to lower their head when looking at the main rearview mirror.

Based on the above analysis and summary, the layout below the main rearview mirror is suitable for long-distance trunk logistics vehicles, and its biggest advantage is to reduce wind resistance. Although the contribution rate may seem small, reducing wind resistance is a systematic project composed of every small contribution.