The following is an introduction to the composition and classification of the semi-trailer suspension: The semi-trailer suspension system consists of elastic elements, guide devices, shock absorbers, buffer blocks and lateral stabilizers. Generally speaking, the trailer suspension system is divided into two types: non-independent suspension and independent suspension. At present, the suspension of domestic heavy-duty trailers is mainly non-independent suspension, and the suspension elastic element is generally a leaf spring suspension elastic element.
The types of domestic heavy-duty trailer suspensions are: leaf spring suspension; air suspension; rubber suspension;
- Leaf spring suspension: It is divided into a small-piece variable-section steel plate suspension and an equal-section leaf spring suspension.
Leaf spring suspension (referred to as leaf spring suspension) is divided into a small-piece variable-section steel plate suspension and an equal-section multi-leaf spring suspension. At present, more than 95% of the domestic heavy-duty truck suspension systems are non-independent suspensions with leaf springs as elastic elements and guide devices. Advantages: simple structure, easy manufacturing, convenient maintenance, mature technology, and reliable operation.
Disadvantages: The trailer has poor ride comfort and comfort; the unsprung mass is large, which cannot adapt to the development of lightweight heavy trucks, and cannot take into account the comfort and handling stability of heavy trucks at the same time. The air suspension makes full use of the variable rigidity characteristics of the air spring to achieve the purpose of taking both aspects into account at the same time. - Air suspension
The air suspension system uses air springs as elastic elements and air as elastic medium. Compressed air (air pressure is 0.5~) is filled in a sealed container, and its elastic effect is realized by using the compressibility of gas. The stiffness of this spring is variable and has ideal elastic characteristics.
At present, there are two main air suspension control modes:
One is manual adjustment using a mechanical height valve. The other is electronic control (ECAS), which greatly improves the performance of the traditional air suspension system and improves the comfort and response sensitivity of the suspension operation. - Rubber suspension
The rubber suspension uses rubber springs as elastic elements. Since the rubber spring has the characteristics of variable stiffness, the entire suspension has a strong load-bearing capacity. Rubber suspension has more advantages than traditional steel plate suspension in terms of load-bearing capacity and reliability, and can adapt to harsh working conditions such as mining operations.
Current status of domestic heavy truck suspension development
There are more than 160 domestic semi-trailer suspension spring manufacturers, spread all over the country, and there are about 80 large-scale professional manufacturers (production scale of more than 8,000 tons). The product quality level has reached the level of advanced foreign countries in the 1990s. Most enterprises are small in scale, with low production concentration and serious problems of scattered and poor quality.
Among them, there are only a few enterprises that have truly formed large-scale and mass production, and most of them are still at the level of simple production technology, with high product costs and difficulty in participating in international market competition. There are only four domestic enterprises that can produce high-end automobile steel plate suspension springs: FAW Group Liaoyang Automobile Spring Factory, Dongfeng Automobile Suspension Spring Co., Ltd., Chongqing Hongyan Automobile Spring Factory, and Shandong Automobile Spring Factory. They all have the ability to produce a variety of laminated springs, gradient stiffness springs, small-piece variable-section steel plate springs, and automobile steel plate springs with double curvature radius and straight sections. There are only three manufacturers in China that can produce suspension springs for buses, trucks, and cars at the same time: FAW Group Liaoyang Automobile Spring Factory, Dongfeng Automobile Suspension Spring Co., Ltd., and Shandong Automobile Spring Factory.
In the field of heavy trucks, each OEM basically has its own leaf spring supporting manufacturer. FAW Jiefang heavy truck leaf spring suspension is mainly supported by FAW Group Liaoyang Automobile Spring Factory; Dongfeng heavy truck leaf spring suspension is mainly supported by Dongfeng Automobile Suspension Spring Co., Ltd.; China National Heavy Duty Truck leaf spring suspension is mainly supported by Shandong Automobile Spring Factory, SAIC Iveco Hongyan leaf spring suspension is mainly supported by Chongqing Hongyan Automobile Spring Factory and Chongqing Hongqi Leaf Spring Factory, and JAC and Valin heavy truck leaf spring suspension is mainly supported by Anhui Anhuang Machinery Co., Ltd.
Air suspension
[Air suspension] Spring is a suspension system used in high-end buses and heavy trucks. It is the development trend of leaf springs in the world. The ultimate development trend of air suspension springs is that spring flat steel is no longer needed or used very little. Air suspension has a history of more than 70 years in developed countries in Europe and America. In the 1950s, air suspension springs began to be used in trucks, cars, buses and railway vehicles. By the 1960s, most buses produced in industrially developed countries such as Germany and the United States were equipped with air spring suspension.
At present, 95% of buses, 80% of trucks and 40% of trailers in Europe and the United States have used air suspension systems, while my country is still in the initial stage. Air suspension systems are only used in some luxury buses and a small number of heavy trucks and trailers. Although the new products launched by various manufacturers such as Sinotruk HOWO-A7, Dongfeng Tianlong, Jiefang J6, and Hualing Xingkaima all have air suspension, it is only in the conceptual stage. It will take some time for them to be truly accepted by the market and to achieve mass production.
This is mainly related to China’s national conditions. Although the domestic efforts to control overloading and over-limit are constantly strengthened, the phenomenon of user overloading is still relatively serious. The air suspension system has not been accepted by customers due to its poor overloading performance, high price, fierce competition in the domestic logistics industry, and meager profits. It can only be used in the transportation of special goods such as precision instruments and electronic equipment.
In fact, the initial cost of the air suspension system is higher than that of the leaf spring suspension system, but according to the experience of use around the world, the total service life of the air spring is longer, generally about 10 times longer than that of the leaf spring suspension system, and less maintenance work, which also helps to extend the life of the semi-trailer. Therefore, the operating cost is lower than that of the leaf spring suspension system, and the higher initial investment can be recovered during the operation process.
At present, there are three main types of automotive air suspension systems on the Chinese market:
The first type is the air suspension system that enters the Chinese market as a whole with the introduction of the model. This type is mainly reflected in the bus market, such as Xi’an Volvo, Changzhou Iveco, Asiastar Benz, etc. This type occupies a dominant position in the Chinese automotive air suspension system market.
The second type is the air suspension system directly introduced from abroad. The delivery cycle of this type of automotive air suspension system is generally more than three months, which is difficult to adapt to the Chinese habit of delivery within one month, and the transportation cost is high. Its biggest drawback is that it is not suitable for China. This type of supplier mainly includes HENDRICKSON Company in the United States, the air suspension production company under the Tuthill Group in the United States, Firestone Tire Company and Goodyear Tire Company in the United States, as well as BPW Axle Company of Germany Vibraco and ContiTech Air Suspension Production Company under Continental Group.
The third category is that local enterprises are based on the introduction and digestion of advanced automotive air suspension system technology from abroad, taking into account the status of Chinese cars, road conditions and transportation characteristics, adhering to the principle of combining advancement and reliability, and conducting secondary development and personalized design according to the specific models of users to ensure the rationality and scientificity of structural matching, tailor-made, and improve the overall performance of the chassis. This type of supplier mainly includes Shanghai Koman Vehicle Components System Co., Ltd., Dongfeng Automobile Suspension Spring Co., Ltd., etc. This type of supplier occupies the mainstream market of domestic air suspension.
Shanghai Koman Vehicle Components System Co., Ltd. is a mainstream air suspension supplier in China. The company was established in 2002 and has become a qualified supplier for nearly 30 well-known domestic automobile companies, including Jinlong United Automotive Industry (Suzhou) Co., Ltd., Xiamen Jinlong United Automotive Industry Co., Ltd., Dongfeng Hangzhou Automobile Co., Ltd., Ou V Bus, and Sinotruk. It has formed a total of 8 platforms, including medium-sized buses, large buses, bus front independent suspension, heavy-duty trucks, and nearly 90 varieties of full air suspension system products. At present, the market share of commercial vehicle air suspension exceeds 20%. [Rubber suspension] Domestic rubber suspension is provided by the American Henderson Company, so it is also called Henderson rubber suspension. Sinotruk chose rubber suspension in the HOWO-A7 series heavy trucks launched not long ago. Previously, FAW Jiefang, SAIC Iveco Hongyan and other companies also launched products using rubber suspension, so the novel suspension structure of rubber suspension has gradually attracted the attention of the industry. Henderson is a multinational company specializing in the design and manufacture of medium and heavy-duty vehicle suspension systems. It is the world’s largest suspension system supplier. The company was founded in 1913 and is headquartered in Chicago, USA. It currently has more than 3,000 employees. In addition to supplying rubber suspension, Henderson is also a major supplier of air suspension in North America, with a market share of more than 75% in the suspension market for heavy trucks and semi-trailers in the United States.
At present, Henderson mainly sells HN522 rubber suspension in China, which is characterized by softer suspension stiffness, improved vehicle smoothness; light weight, increased payload, reduced tire wear, reduced maintenance costs, and higher resale value; variable suspension stiffness, auxiliary rubber springs, lateral and longitudinal stabilizer bars, etc., to improve vehicle stability and safety. In addition, Henderson also cooperated with China National Heavy Duty Truck to develop the RS-850 (load capacity) heavy-duty vehicle suspension system project, which other competitors in the industry cannot match in similar heavy-duty suspension systems.
