NOVEMBER is due to see the commissioning of an advanced multi-function bogie test plant at China Southern Locomotive & Rolling Stock Corp's Sifang works in Qingdao.
Being supplied by Swiss precision hydraulics specialist Nencki AG, the unit is the third, and most advanced, bogie test stand that the company has built for China.
Nencki has been developing its range of bogie test stands over several years, including a highly versatile unit supplied to Swiss Federal Railways' Yverdon works in 2006, specifically to test the bogies for SBB's ICN tilting inter-city trainsets. This year the supplier has won orders to supply a test stand to Delhi Metro Rail Corp via German partner Neuero, and a 25-tonne unit to test three-axle locomotive bogies at the Dalian loco works in China. Bogie test stands are under construction for Nanjing Puzhen Co in China and for Polish rolling stock manufacturer Pesa. Another unit will be exported to Iran through Nencki's German partner, and the most recent order is to supply two stands to Changchun Railway Vehicles.
A team of Chinese engineers visited the Nencki plant in Langenthal at the end of August to undertake pre-acceptance tests of the completed rig for Sifang. After this the unit was partially dismantled and shipped to Qingdao for final commissioning.
With Sifang turning out around 1 200 coaches a year using between 20 and 30 different bogie types, the test stand has been designed with a high degree of flexibility. It is also able to cope with bogies of different gauges between 1 000 and 1 676 mm, in order to test vehicles produced for export.
The fully computer-controlled test rig is designed to assess all aspects of bogie geometry and performance, both for quality control of new bogies and for checks after heavy maintenance.
Installed in a workshop pit, the stand has retractable rails which position the bogie wheelsets accurately onto a set of adjustable drive and sensor mountings. A standard series of tests looks at wheel profile and roundness, axle back-to-back distances, wheelbase and parallelism of the axles, plus the degree of flex or distortion in the bogie frame.
Three load sensors under each wheel support allow the unit to measure individual wheel loadings and the performance of both primary coil and secondary airbag suspensions. A portal frame supports hydraulic presses that can replicate the vehicle loadings on the support points, imposing tare or gross weights as required. The locally-developed test software can even calculate the thickness of shims required to adjust a coil spring and equalise the dynamic performance of the four axleboxes.
China is now entering the high speed club with trains running at up to 250 km/h and 300 km/h envisaged soon. So Nencki has developed a facility specifically to measure the risk of a stiff bogie riding briefly on three wheels. There is an enhanced risk of derailment when a bogie in this condition passes through the transition coming off a section of line with a high degree of cant.
Each set of test results is logged, and each reading is checked against the permitted tolerances. A simple yes/no report is produced for the operator, but the full set of data is recorded in the database for long-term analysis, and for auditing purposes in the event of any incident. As part of the customisation of the bogie test stand for Sifang, Nencki has developed a full suite of Chinese language menus and reports, as well as its usual German, French and English options.
Nencki AG, Switzerland
