Air springs withstand endurance test

Covering an area of 2.7 million square kilometres, Kazakhstan is the ninth-largest country in the world. Long railway routes across its country pass through areas of searing heat and icy cold and are subjected to extremes of temperature and climatic change. Thanks to an all-new material mix, ContiTech has successfully developed reliable train air springs that even work in such hostile conditions.

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Rail vehicles carry people and goods swiftly, safely and reliably to virtually every corner of the Earth. Often, the materials they are made from are exposed to extreme stresses and strains. But complex factors of this kind are no problem for caoutchouc-based air spring systems by ContiTech Railway Engineering. Capable of withstanding even the toughest conditions, these innovative products have been proving their credentials in extreme temperatures and under severe abrasion since early 2014, on the railway link between Astana and Almaty in faraway Kazakhstan.

Kazakhstan is a land of geographical and climatic extremes. Covering an area of 2.7 million square kilometres, it is the largest landlocked nation in the world. Its northern border to Russia is some 6,800 kilometres long. Borders to the east, west and south are even longer. Measuring some 7,000 kilometres, they lead along the Caspian Sea and the edges of China, Uzbekistan and Kyrgyzstan. The landscapes in Kazakhstan are impressive, with huge mountains as well as sandy and rocky deserts and vast steppes. The climate is strikingly continental, with temperatures ranging from 40°C below zero in the winter up to 40°C plus in the summer.

For the capital, Astana, and the 17.8 million people in total who live in the region, the railway is the most important means of travel and transport. One of the key lines in the area is 1,100 kilometres long and links the metropolis with the town of Almaty, which is located on the silk road, one of the most famous trading centres in Kazakhstan. In these parts, then, a train has to withstand not only the searing heat but also the icy cold. Moreover, with sand and dust being just as damaging as high UV and ozone levels, any materials used here have to withstand completely new dimensions of robustness. The best example is ContiTech’s air spring systems, specially developed for railway vehicles.

New air springs for the extreme cold

Air springs by ContiTech enhance comfort and safety, especially in metro trains, trams and regional public transport. As part of the secondtier suspension, they are situated between the chassis and the bogie. Here they absorb impacts, allowing bumps and vibrations caused by the tracks to go virtually unnoticed by passengers. Variable pressure inside them allows train wagons to maintain consistent levels, irrespective of the load on board – in the most hostile of conditions and for years on end.

“Unlike with commercial vehicles or passenger cars, there’s no way of changing components in railway vehicles for summer or winter operations. So our air springs have to work reliably all year round. The diverse climates and temperature ranges and the huge risk of abrasion and dust in Kazakhstan make this a particular challenge,” explains Friedrich Hoppmann, Head of ContiTech Railway Engineering.

“In setting out to find the ideal solution, we wanted to combine the advantages of natural and chloroprene rubber and a textile carcass to create a completely new material mix that’s resistant to even the lowest of temperatures as well as extreme abrasion and the influences of UV and ozone,” says Jörg Frohn, Head of Research and Development with ContiTech Railway Engineering.

Solution in the test lab

ContiTech Air Spring Systems runs the world’s only accredited test lab for air springs for rail vehicle suspension systems according to ISO/ICE 17025. Based in Hanover, it has the best research and simulation equipment available. In the lab’s unique, integrated cold chamber, air spring specialists from ContiTech were able to stress-test their innovations authentically in realistic climate conditions. This allowed them to draw reliable conclusions about whether or not their product would operate faultlessly at minus 50°C before any practical testing was even carried out.

“The K air spring has been in operation on the route between Astana and Alamty since January 2014. It will now prove its worth in long-term operations. That way, we will be able to convince other customers of the benefits it offers for trains that operate in extreme climates and weather conditions,” adds Friedrich Hoppmann.