Truck lightweighting

 

The China Green Freight Initiative (CGFI) advocates for green management, green technology, and green driving, namely the "three greens" concept. Among them, the green technology aspect actively promotes reducing fuel consumption by lowering the curb weight of trucks to reduce costs and improve efficiency. This is the subject of this article: truck lightweighting.

I. Significance of Promoting Truck Lightweighting

The size of a vehicle's own weight is one of the important factors affecting fuel consumption, so vehicle lightweighting design has become a development trend. For the freight and logistics industry, reducing fuel consumption is the key to energy saving and emission reduction. Achieving truck lightweighting, reducing fuel consumption, increasing load capacity, and improving transportation efficiency are crucial for the sustainable development of China's freight and logistics industry.

(1) Relationship between Truck Lightweighting and Fuel Consumption

The power of the engine is mainly consumed in overcoming the vehicle's driving resistance, which consists of air resistance, rolling resistance, acceleration resistance, and climbing resistance. Air resistance is mainly related to the shape of the vehicle body and the windward area, especially at high speeds, but it is not related to the total mass of the entire vehicle; however, rolling resistance, acceleration resistance, and climbing resistance (excluding air resistance) are all proportional to the total mass of the entire vehicle. Therefore, reducing curb weight is an important factor in reducing these three types of resistance, and it is also an effective measure to reduce fuel consumption. According to relevant foreign test data, a 10% reduction in vehicle curb weight can reduce fuel consumption by 6% to 8%. For trucks, reducing curb weight also increases the effective payload, increasing the mass utilization coefficient, thereby improving transportation efficiency and reducing transportation costs, which also relatively reduces fuel costs.

(2) Relationship between Truck Lightweighting and Exhaust Emissions

Fuel consumption and exhaust emissions are closely related. Vehicle exhaust is a major cause of the greenhouse effect and air pollution, especially the emission of carbon dioxide, which has been increasing sharply in recent years. Major countries around the world have already formulated or are in the process of formulating strict regulations to limit fuel consumption and emissions. China's newly revised "Environmental Protection Law" and various measures to reduce motor vehicle emissions have prompted the trucking industry to find effective ways to reduce emissions through technological innovation. Relevant statistics show that for every 100 kg reduction in vehicle weight, fuel consumption can be reduced by 0.4 liters per 100 kilometers, and carbon dioxide emissions can be reduced by 1 kg. Therefore, achieving environmental protection through vehicle lightweighting has become an important direction for the development of automobiles, especially trucks.

(3) Relationship between Truck Lightweighting and Transportation Services

The purpose of truck lightweighting is to reduce vehicle weight as much as possible while ensuring safety performance and strength, enhance vehicle power performance, reduce fuel consumption, and reduce exhaust pollution emissions. Currently, China implements a standard of 49 tons for the total weight of vehicles and goods. For transportation companies to make money and avoid fines, truck lightweighting is a viable path. From the perspective of freight companies, reducing the weight of trucks can save raw material consumption, reduce production costs, improve market competitiveness, and achieve direct economic benefits. Under the same transportation conditions, shippers will prefer lighter, lower fuel consumption vehicles, and lightweight design can better meet customer requirements. Therefore, achieving truck lightweighting has a positive promoting effect on freight companies obtaining transportation services that are accepted by shippers.

II. Truck Lightweighting Technology

Using lightweight metals and non-metallic materials, or using modern design methods and effective means to optimize and design trucks, while ensuring the comprehensive performance of the vehicle, minimizing the weight of the truck itself to achieve comprehensive performance indicators of weight reduction, reduced consumption, safety, and environmental protection. However, truck lightweighting is not simply making it lighter; it should be done without affecting the original performance of the vehicle. It must effectively reduce the weight of the vehicle while ensuring the safety, crashworthiness, vibration resistance, and comfort of the vehicle during driving, and at the same time not increase the cost of the vehicle itself to avoid increasing the economic pressure on users' vehicle purchases. Therefore, truck lightweighting technology mainly includes: structural lightweighting technology, key component lightweighting technology, and new material technology application.

(1) Structural Lightweighting Technology

Starting with changing the vehicle structure, the goal of structural lightweighting is achieved through structural optimization, partial weight reduction, and the use of new structures. For example, changing the frame longitudinal beam from double-layer to single-layer and locally reinforcing parts with larger loads.

1. Application of high-strength steel in the frame of tractors, changing the frame longitudinal beam from double-layer to single-layer;

2. Shortening the wheelbase and rear overhang of the tractor to improve maneuverability, reduce curb weight, and meet national standards for the length of vehicle combinations.

(2) Key Component Lightweighting Technology

On the premise of meeting the usage requirements, the weight reduction of the vehicle's core externally purchased components is carried out. For example, selecting new types of axles, fewer-leaf spring suspension systems, and disc brakes instead of drum brakes.

1. Axle lightweighting technology;

2. Air suspension technology;

3. Fewer-leaf spring suspension system;

4. Single-wide tire technology.

(3) Application of New Materials Technology

Using lightweight materials (such as aluminum, magnesium, ceramics, plastics, glass fiber, or carbon fiber composite materials) for vehicle structural design, such as using aluminum alloy shell gearboxes and other new material gearboxes.

1. Application of new materials such as aluminum alloy rims, gearbox housings, fuel tanks, radiators, bumpers, and rims in vehicles;

2. Promotion and application of disc brakes in tractors.

III. Current Status of Truck Lightweighting in China

Currently, China has accelerated the pace of technological development of new vehicle models through joint ventures, cooperation, and technology introduction with internationally advanced automobile-producing countries, and the application of lightweight materials in trucks has also accelerated. With the increasingly fierce internationalization of competition in the Chinese automobile market, domestic trucks need to reach the level of similar foreign vehicles, so the expanded application of new lightweight materials is imminent. Currently, major domestic truck manufacturers have proposed independent development strategies, and some have already started lightweighting research. Because domestic trucks have a larger curb weight than similar foreign vehicles, and the mass utilization coefficient gap is also larger, they have greater development potential.

According to investigations by relevant institutions, in terms of single vehicle energy efficiency, China's heavy truck energy consumption is about 20%-30% higher than that of the United States. The reason is that the research on lightweighting of trucks in China started late, and lightweighting technology has not received enough attention in the manufacturing and use of ordinary trucks. At the same time, the numerous brands and structures of trucks in China, inconsistent performance and quality, insufficient application of new structures, new processes, and new technologies, and low levels of specialization and standardization are all important factors hindering the ideal development of truck lightweighting in China.

However, with the overall requirements for energy conservation and emission reduction in China, the Ministry of Transport has proposed that it will focus on promoting the introduction of standardized policies for commercial vehicle models in the future, and with the advocacy of the China Green Freight Action, the standardization, specialization, lightweighting, and cleaning of freight vehicles have been proposed. Chinese freight and logistics companies, especially those with strong professionalism, are moving towards lightweighting.

Taking cold chain transportation as an example, with the continuous increase of transportation vehicles nowadays, 'lightweight design' has become an urgent need to reduce emissions from global transportation vehicles. Product lightweighting is one of the development trends in refrigerated and insulated vehicle technology. With the continuous improvement of the mass utilization coefficient of automobile chassis and the rapid development of highway construction, in the face of high logistics transportation costs, the momentum of accelerating the development of heavy-duty vehicles will be further strengthened. This requires improving the strength and stiffness of the chassis, while paying special attention to reducing the weight, increasing the dimensional stability and impact resistance after loading, ensuring the reliability and safety of the whole vehicle, and meeting the needs of freight companies for high efficiency and profitability.

IV. CGFI Lightweighting Requirements for Green Freight Vehicles

In view of the relatively lagging development of truck lightweighting in China and the needs of the future development direction of truck lightweighting, one of the important contents of the "CGFI Green Freight Vehicle Standard" formulated by the China Green Freight Action is to encourage truck lightweighting, that is, to encourage the improvement of the payload utilization coefficient of commercial vehicles. This is an important part of the lightweighting technology promoting the development of green freight.

The difference between commercial trucks and ordinary vehicles lies in the fact that commercial trucks are used for production through the transportation of goods, so the transportation capacity of trucks is a very important indicator. The payload utilization coefficient reflects the ability of transportation vehicles to transport goods under the same curb weight. Under the premise of ensuring safety, the higher the payload utilization coefficient, the higher the vehicle's technical level. Therefore, in the CGFI green freight vehicle standard, referring to the requirements for the vehicle's payload utilization coefficient in the draft for soliciting opinions on the "Technical Requirements for Urban Logistics Delivery Vehicles", the technical requirements for green freight vehicles are proposed.

Payload Utilization Coefficient Limit Requirements for Green Freight Vehicles

Vehicle Type	N1		N2		N3
Gross Weight M (kg)	M ≤1800	1800 ≤3500	3500 ≤4500	4500 ≤12000	12000 < M ≤16000	16000 < M ≤20000	20000 < M ≤24000	M > 24000
Ordinary Truck	≥0.65		≥0.75	≥0.85	≥1.0	≥1.1	≥1.2	≥1.3
Dump Truck	≥0.55		≥0.65	≥0.75
Box Truck	≥0.50		≥0.60	≥0.90	≥1.3
Closed Truck	≥0.35	≥0.60	≥0.65	≥1.10	—

V. Restricting Factors in the Development of Truck Lightweighting

In early 2014, the Ministry of Transport proposed the "Four Transportations" development strategy, and the industry began to comprehensively deepen reforms. Transformation and upgrading, low-carbon green circulation, and sustainability have become important guiding principles for industry development. Under the policy of establishing a resource-saving and environmentally friendly society for energy conservation and emission reduction, the concept of truck lightweighting has been increasingly valued by more and more institutions. However, the current practical effect of truck lightweighting is not good because of the following restrictive factors.

(1) Overloading hinders lightweighting

Overloading can be said to be a stubborn problem in China's road transportation. With increased efforts to control it, the phenomenon of overloading will decrease, but once there is any relaxation, it will resurface. This is also a universally acknowledged major obstacle affecting the continued development of truck lightweighting in China. On the one hand, overloading offsets the energy-saving and efficiency-enhancing effects of lightweighting; on the other hand, some freight companies, in order to overload, directly agree with modification plants and even vehicle manufacturers to require the manufacturers to make the trucks heavier. Therefore, only by thoroughly solving the problem of overloading can lightweighting be truly implemented.

(2) Materials hinder lightweighting

The application of new materials is one of the three major technologies for truck lightweighting. However, the real difficulty lies in the research and use of new materials. Studies have shown that the application of new materials is the main way for foreign trucks to achieve lightweighting, and the reduction of vehicle weight mainly relies on the application of new materials, with aluminum, magnesium alloys, and engineering plastics being widely used. For some automatic valves, if plastic is used instead of metal parts, the vehicle weight can be reduced by at least half. Developed countries in Europe and America began to research the application of new materials twenty years ago, while China started late and still has a considerable gap compared to them.

(3) Relevant standards and regulations need to be accelerated

Any technology with innovative significance is closely related to the country's policy orientation. Foreign truck lightweighting practices show that policy guidance, a sound legal system, the fundamental role of standards and specifications, and the application of industry management measures that coordinate and unify vehicle manufacturing and vehicle use departments are all important driving forces for truck lightweighting. At the same time, advocacy-oriented industry self-discipline documents issued by freight and logistics industry associations are also important supplements. However, China currently lacks national and industry standards on lightweighting, and laws and regulations are not sound in this area, which is an important restrictive factor for truck lightweighting.

VI. Policy Recommendations

In order to accelerate the development of truck lightweighting in China, the following policy recommendations are put forward to the government authorities:

1. Systematically study the current status of vehicle lightweighting research and application abroad;

2. Improve national standards and relevant laws, regulations, and industry regulations;

3. Strengthen the research on structural lightweighting technology in truck lightweighting;

4. Approve the application of lightweight components certified by third-party testing institutions as legal modifications;

5. Strengthen the research of new material technology and increase the promotion of new material applications;

6. Amend the "total mass limit" regulations for freight vehicle lightweighting in the GB1589 national standard;

7. After technical demonstration, the relevant provisions on the vehicle payload utilization coefficient in the green freight vehicle standards for the promotion of China's green freight action should be adopted during policy formulation;

8. Include lightweight vehicle models in the scope of financial subsidies, and provide higher subsidies for vehicle models equipped with air suspension and other configurations.

Achieving freight vehicle lightweighting is not only one of the important hallmarks of China's progress towards becoming a strong industrial nation, but also an important driver of the sustainable development of China's freight and logistics industry, and an important means of energy conservation and emission reduction in China's transportation industry, especially the road freight industry. This is a major issue in the long-term pursuit of green technologies in China's Green Freight Action. Although China's freight vehicle lightweighting currently lags behind international advanced levels, as long as policies are formulated, goals are clarified, and measures are effective, China's freight vehicle lightweighting industry will appear before people in a new way.