Comfortable and Safe Travel

November 2011 ContiTech air springs enable buses from the Chinese manufacturer Yutong to withstand extreme conditions.

China is a vast country with variable weather conditions: the Middle Kingdom has 18 different climate zones. These diverse climate conditions place the greatest demands on materials, which must work reliably and last as long as possible in all areas of the country. This also applies to air springs, which help make bus journeys comfortable and safe whatever the season.

China’s largest bus manufacturer, Zhengzhou Yutong Bus Co. Ltd. which ranks No. 2 worldwide, has been relying on products from ContiTech Air Spring Systems for many years. As buses are people’s main means of getting from A to B, they travel long distances under arduous conditions – and must therefore be constructed from long-lasting, reliable components. In their search for the optimum air spring for China’s buses, Yutong and ContiTech have intensified their development partnership. Together, they use highly advanced measurement technology to examine the diverse stresses and loads to which the air springs are exposed.

“In building up our business in Asia and South America, we have learned that we need to work with customers to expand our knowledge of specific regional factors such as climate and road conditions so that we can develop the optimum air springs for each market,” commented Hubertus Gawinski, Head of Research and Development at ContiTech Air Spring Systems in Hanover.

The material experts are well aware of the factors that influence an air spring’s service life. Firstly, there is the operating pressure, which is created when a bus is filled with passengers and luggage. Secondly, the amplitude is important. Here, it is a matter of to what extent the air springs are dynamically deformed during operation whilst the vehicle is traveling along uneven ground. Thirdly, the ambient temperature plays a major role – especially in the diverse climate zones found within China. “The key question now is which combination of the three factors is representative for the regions and thus determines the service life of an air spring. This data is not only relevant to us. Vehicle engineers also vastly benefit from this knowledge because it helps them design vehicle structures enabling, for instance, better positioning of the exhaust gas lines that provide additional heat to the air springs. To do this, it is necessary to measure the data during live operation,” explained Gawinski.

Yutong was impressed by this approach and worked with ContiTech to equip two buses with state-of-the-art measurement technology so as to record the operating pressures, amplitudes and temperatures to which the air springs were subjected during journeys in the various regions, during the different seasons and on the diverse road surfaces. The measurements were transmitted wirelessly to the laboratory in Hanover and used to develop air springs that most closely meet the individual requirements of Yutong buses on China’s roads: air springs that withstand high stresses and loads to further stabilize the driving dynamics in all weather conditions over many years while also improving passenger safety.