The country's railway operator, China Railway Corp, has asked German machinery manufacturer Voith GmbH to stop providing gearboxes to Chinese trainmakers for safety reasons, China Business News reported on Monday.

China Business News said a total of 45 technical breakdowns, including cracks and bearing faults, have occurred on Voith's gearboxes on the electric multiple unit trains on high-speed rail lines of Wuhan-Guangzhou, Beijing-Shanghai and Harbin-Dalian after June 2012.

China CNR Corp Ltd installed more than 100 new Voith gearboxes earlier this year but said it found technical problems while operating them.

Gearboxes are key equipment in the power transmission systems of high-speed trains. Because they are intricately related to driving safety, train manufacturers demand that the products have a high level of accuracy and reliability, as well as sophisticated design technology.

Voith's Shanghai gearbox plant was also asked to temporarily halt production, according to the report.

Neither Voith's global headquarters nor its China branch would respond to media requests for comment. They also declined to answer an e-mail sent by China Daily. CNR was not available for comment on Monday.

Voith, one of Europe's largest family-owned businesses, has more than 40 years of experience in supplying gearboxes to the global market. It also provides them for high-speed trains of Germany's Intercity-Express rail service.

Wang Guiqing, vice-president of the China Chamber of Commerce for Import and Export of Machinery and Electronic Products, said the chamber is paying close attention to the issue as two member companies - China CNR Corp and CSR Corp, the nation's two largest trainmakers - use German gearboxes to assemble their products. Both also sell trains on the global market.

Wang said the chamber is willing to help the companies seek alternative gearbox suppliers to ensure operational safety and find out the reason for previous malfunctions.

"Apparently, the CRC's decision on Voith's gearbox products is quite tough for the company," said Zhao Jian, a professor of railway development at Beijing Jiaotong University.

"But it will have a series of effects on EMU manufacturing, operation and maintenance. Chinese trainmakers may face difficulties such as work delays or spending time to seek new suppliers, which will affect vehicle delivery schedules."

Zhao said high-speed trains in China, especially in its southern region, have to pass through many rail tunnels, so foreign rail part suppliers must consider the wind tunnel effect, which can cause cracks in machinery.

Contact the writers at zhongnan@chinadaily.com.cn and zhuwenqian@chinadaily.com.cn