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With the improvement of heavy-duty transmission production capacity, the improvement of product mix, and the improvement of self-provisioning rates of domestic mainstream heavy-duty truck manufacturers such as China National Heavy Duty Truck Group and China FAW Jiefang Co., Ltd., China's heavy-duty transmission market is undergoing a major change. What caused the reporter’s concern in this change is that from the technical route, neither China National Heavy Duty Truck nor the heavy-duty transmission developed by FAW has not opened up a new road, but chose unanimously the dual products that have already become mainstream products in the market. Intermediate shaft structure transmission, as a breakthrough point.
Fast, which occupies approximately 80% of the domestic heavy-duty transmission market, is well known for the development and production of double countershaft transmissions, while Sinotruk and FAW Liberation and other companies are not willing to avoid the advantages of Fast and are developing in the development of twin countershaft transmissions. Making a big fuss, we can see that the double countershaft transmission won the favor of the entire vehicle company. Industry insiders estimate that more than 90% of heavy trucks currently sold domestically are equipped with twin countershaft transmissions.
Compared with single countershaft transmissions, what are the advantages of heavy-duty twin-shaft transmissions? What are the characteristics of heavy-duty double countershaft transmissions developed and produced by each of the above companies?
Different companies produce
Dual countershaft transmissions are different
Fast can develop into the largest heavy-duty transmission manufacturer in China and even in the world. The double countershaft transmission is a must. Fast has established the market base for double countershaft transmissions in the domestic heavy truck field. In the past two years, some heavy truck companies have developed their own double countershaft transmissions. However, in the development of their products, they have made corresponding adjustments and improvements in the design for the current situation where the engine power of the heavy-duty trucks is getting larger and higher and the bearing capacity of the transmission is increasingly higher.
"Fast, China National Heavy Duty Truck, and FAW Jiefang Transmission Co., Ltd. developed a heavy-duty twin countershaft transmission with a very close main box structure. They all use double countershafts and their sub-tank structure is different." Vice President, FAW Liberation Gearbox Xia Zhongfa, the manager, told the reporter that although the transmission deputy boxes of Fast and Liaison Transmission Co., Ltd. are both double-shafted, the types of gears used are different. Fast uses a straight-tooth drive, Liberated Gearbox adopts a helical gear transmission, which has a stronger bearing capacity and a smoother transmission. The heavy-duty transmission of China is equipped with a planetary gear box as a deputy box, and this kind of structure is also equipped with a double box. The auxiliary shaft of the countershaft and spur gear drive has a stronger carrying capacity.
"In theory, although the helical gear transmission structure and the planetary gear transmission structure of the auxiliary box, than the straight gear transmission of the auxiliary box performance is more superior, but the processing is more difficult, if the processing is not in place, the transmission is more prone to failure." Yang Lin, director of the Institute of Special Gear Research, said.
Fast has been trying to improve the carrying capacity of the auxiliary box. In previous years, Fast had tried to develop three intermediate shafts. “At present, Fast is developing a large center-to-center deputy box. Its carrying capacity is stronger, which is conducive to prolonging the life of the transmission.†Yang Lin told reporters.
Double countershaft transmission suitable for Chinese market
At present, there are mainly two types of manual heavy-duty transmissions equipped with heavy-duty trucks in the world. The single intermediate shaft structure represented by German ZF technology and the double intermediate shaft structure represented by Eaton Technology of the United States.
In the 1980s, the predecessor of the factory, Shaanxi Gear Factory and the former Minjiang Gear Transmission Co., Ltd., the Minjiang Gear Factory, respectively introduced the heavy-duty transmission technology from Eaton and ZF. Since then, after more than two decades of development, Fast dual twin shaft transmissions have established a leading position in the heavy truck market, and the tooth decay has gradually faded out of the heavy truck market, becoming the largest medium and large passenger vehicle transmission manufacturer in China.
“The strong carrying capacity is suitable for the use environment of heavy trucks in Chinaâ€, which is the evaluation of double countershaft transmissions by many insiders.
Xia Zhongfa believes that bearing capacity has a lot to do with product design. Both single-shaft and double-shaft transmissions can improve bearing capacity by changing product design parameters. Many single-shaft transmissions also have strong bearing capacity.
Xia Zhongfa pointed out that in terms of the current market environment in China, double countershaft transmissions have certain advantages. First, when the transmission torque reaches 1000N·m or more, the cost advantage of the double countershaft transmission is obvious. At present, the truck users in China are still relatively sensitive to the cost; secondly, when the bearing requirements are high, compared with a single countershaft, the twin countershaft transmission pairs the gears. The processing requirements are low and are in line with the current domestic processing level. He told reporters that now FAW produces single- and double-shaft heavy-duty transmissions at the same time. In contrast, single-shaft transmissions have a slightly higher cost when the transmission torque is the same.
"With a transmission with the same calibrated input torque, the twin countershaft transmissions are smaller, lighter, cheaper, and relatively simpler in construction," said Yang Lin.
Double countershaft transmission with synchronizer is a bit difficult
In addition to the different number of intermediate shafts, there has been a significant difference between the single and double countershaft transmissions. One single countershaft transmission has a synchronizer, and a double countershaft transmission does not have a synchronizer. With double countershaft transmission heavy trucks equipped with no synchronizer, the two-foot clutch is stepped on during shifting, and the driver's operation is more complicated.
"In order to combine the convenience of shifting and the bearing capacity, Zhejiang Wanliyang Group Co., Ltd. has developed a transmission with a single countershaft and a secondary countershaft in the main box and has applied for a patent." Renhua Lin, General Manager of Wanli Yang heavy truck transmission products Say.
In order to solve the problem of the double countershaft transmission with a synchronizer, Fast has made corresponding efforts. According to reports, at present, Fast double twin shaft transmissions can be equipped with synchronizers, and Fast has sold many double countershaft transmissions with synchronizers.
Although the synchronizer is used to make shifting of vehicles more convenient, some people think that the domestic dump trucks and other engineering vehicles have poor working conditions and frequently shift gears, causing the friction belts of the synchronizer to be easily worn, resulting in transmission quality problems; without the synchronizer Transmission, but the structure is simple and practical. “Technically, the development direction of domestic heavy-duty transmissions is high load, low noise, light weight, and easy operation. After 5 years, what kind of application status of single- and double countershaft transmissions on domestic heavy-duty trucks is difficult at present. Forecasting.†Xia Zhongfa said.