1．目的及意义

Road wreckers are also called trailers and accident rescue vehicles. It consists of a chassis, lifting device, lifting traction device, hydraulic system, electronic control system, body and toolbox. It is equipped with lifting, dragging, lifting and other devices on the basis of a dedicated cargo chassis. It has a number of functions such as lifting, dragging and lifting, and is applicable to clearing operations of highways and city roads. Compared with other special vehicles, road wreckers have a relatively short history of development. They are mainly used to clear accident vehicles and eliminate road obstacles. Side road wreckers are characterized by the ability to lift accidents or faulty vehicles from the side.

China's road wreckers started in the early 1990s. At that time, the social demand was small, and the style structure was mostly in the form of hanging. With the acceleration of the highway process in China, the demand for wreckers entered the outbreak period after this century. The wrecker technology has also been greatly improved, and product design techniques and manufacturing processes have also achieved breakthrough development. In the past 20 years, the wrecker industry in China has gone through the process of introducing complete vehicles, absorbing imitations, and independently researching and developing wreckers. The type and level of products have been gradually increased and improved from the original suspension type and flat-bottom type.

However, we still have a big gap compared with the advanced developed countries' wrecker technology. For example, the U.S. wreckers started earlier, advanced technology, and the product has three major characteristics. First, the variety is full-featured. From light to super heavy tonnage, there are all kinds of wreckers with different specifications and functions. Second, the structure is novel and beautifully manufactured. The overall appearance is beautiful and full of creativity, and the structure is compact and nuanced. Third, new materials and new technologies are widely used. For example, high-strength plastic materials are used for the body of wreckers, and aluminum-type materials are used for rolling shutter door type toolbox doors and aluminum flat plates. In terms of system monitoring, integrated control, etc., advanced electronic control technologies and equipment are also commonly used. This makes the wrecker safer and more reliable to use.

In addition to technology, the gap is also reflected in the company itself, national conditions and other factors, thus constraining the development of the wrecker industry. The main problems existing in China's wrecker industry are: (1) Announcement management system constrains industry development. China's wreckers use product announcement management, the Ministry of Industry and Information is responsible for product announcements, the Ministry of Environmental Protection is responsible for environmental protection announcements, the AQSIQ is responsible for the 3C announcement, the public security traffic control is responsible for vehicle licenses, and the Ministry of Transport is responsible for fuel announcements. The announcement of product announcements has a long process cycle and is not conducive to the research and development of new products. In addition, the production volume of wrecker vehicles is clearly different from that of passenger vehicles and ordinary trucks. The number of passenger cars and trucks is large, and a certain model can sell tens of thousands of vehicles or even hundreds of thousands of vehicles. The production of wreckers is based on market orders, which are mainly modified on the basis of the second-class chassis of trucks. For many varieties, small volume production, market promotion limited, may only sell a few vehicles a year. (2) Poor adaptability of relevant industry standards. For example, the "Technical Conditions for Motor Vehicle Operation Safety" (GB 7258-2012) regards the on-board quality of dedicated vehicles as a limiting parameter. It is unreasonable to neglect dedicated functions. Since the chassis quality of some models is small, manufacturers must not meet the requirements for carrying quality. Does not reduce or reduce the special functions, learn from the foreign special-purpose vehicles to their total mass restrictions, cancel the requirements of quality requirements. (3) Product intellectual property is not protected. Due to the restrictions of announcement management, in order to bring wreckers to market as quickly as possible and expand the coverage of product use, Chinese production companies pay attention to the realization and maximization of product functions, often neglecting product details. Processing and optimization design. In addition, the vicious competition among enterprises, product imitation, blind pursuit of the low price, resulting in domestic wreckers cheap but not beautiful things, product quality is difficult to improve. (4) Production companies blindly pursue large and complete. The gap between domestic and imported wreckers is mainly reflected in the word “professional”. The more specialized vehicle manufacturers, the less products they can produce. The wrecker manufacturers in foreign countries are all focused on researching and producing their own specialty products. The scale is generally not large. They mainly rely on specialization and excellence to achieve market recognition and dominate the market in their respective fields. In particular, the production companies in Europe, the production methods for the former shop after the factory, specialized division of labor, modular assembly, variety changes quickly, quality assurance, high production efficiency. Therefore, wrecker manufacturers should not be large and complete. They should take the path of specialization to do a good job in the market and do a good job of services. (5) Chassis and key components can not keep up. At present, the biggest problem faced by domestic wreckers is the lack of dedicated chassis, such as high-power pickup trucks, heavy-duty chassis with more than 40 tons. Due to the small quantity and low price of other accessories, supporting enterprises are unwilling to develop them, affecting the development of the types of wreckers and improving the performance and technical level. (6) China lacks unified management norms and standards. China's roadblocked, rescue, rescue, and smooth services were opened to the public as market behaviors, and they gradually became socialized after 2000. Most of the social obstacle-relief and rescue enterprises were established less than ten years ago, from the industry's operational norms to the strengths, services, and management of enterprises. Other aspects are in the starting stage. In particular, the low barriers to entry for the rescue industry and the uneven quality of service and service have caused vicious competition in the road clearance and rescue market in China, and the decline in corporate integrity has seriously affected the survival and development of the road evacuation and rescue industry. This also affects the overall sustainable development of China's wrecker industry.

With the acceleration of the development of traffic road construction in China, the market demand for wreckers is also increasing. Its main development trend is gradually extended to humanized design and humanized services. In the future, China's wreckers should be extended to two ends in tonnage. For example, the small tonnage is less than 3.5 tons and the large tonnage is more than 56 tons. The small tonnage is dominated by pickup trucks, which is light and flexible to meet the rapid rescue in different urban environments. For large tonnage, in addition to more than five axes, semi-trailer flat wreckers should be developed to meet the rescue of large passenger cars on the highway. Secondly, the key to the development of multi-purpose wreckers lies in the functional arrangement of the vehicle, appearance design, and control automation. It provides more convenient and user-friendly operations for the use of customers, such as increasing the crane, multi-winch, and emergency equipment. Among them, the side road wrecker is a developing vehicle. It is more convenient than ordinary road wreckers and it also has less site requirements. Therefore, it has important research significance for the overall arrangement and design of roadside wrecker.

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2. 研究的基本内容与方案

{title}(1) The basic research content of this paper is as follows:
①The paper will outline the situation and research significance of light side road wreckers at home and abroad.
②According to the requirements of working conditions, the thesis will select the type of vehicle chassis structure and the overall layout.

③The paper will do some design and calculation for the road-removed wrecker's clearing mechanism.

(2) Research objectives:
The design is planned to be based on a road wrecker and to lift the accident or faulty vehicle from the side.It is equipped with a lateral lifting mechanism to achieve the purpose of eliminating obstacles and saving time.

(3) Proposed technical solutions and measures：

The choice of the wrecker chassis: As the wrecker is a special-purpose vehicle, the performance of the chassis plays a decisive role in the performance of the wrecker. So the key to choosing the chassis is to make the chassis meet the requirements of the special device. Because the light wrecker is based on ground operations, the chassis of the second type of wagon is selected as the chassis of the design wrecker.
The overall layout of the wrecker: First of all, the task of the overall arrangement is to make the special device and the chassis of the car match each other in order to obtain better basic performance and special performance of the wrecker. The side position wrecker is based on a flat wrecker, and a lifting mechanism is added to the side of the wagon to connect the power take-off to the low gear of the gearbox or the output shaft of the sub-tank to output power to the external working device. The overall arrangement parameters of the wrecker include profile dimensions, wheelbase, rear suspension and mass parameters. The dimensions of the outer dimensions are 7338×2350×2430 (mm), the wheelbase is 3800mm, the total mass is 8200kg, the trim mass is 4500kg, and the front suspension/rear suspension is 1068/2470mm.