Leaning to Retrofit

Leaning to Retrofit

By Michael Valenti, Associate Editor

Tilting trains are an alternative to pricey dedicated track for new high-speed trains, but their cost is still far from negligible. Retrofitting an active tilting system to existing rolling stock can provide an even less expensive option for fast train travel.

Waggonfabrik Talbot in Aachen, Germany, has developed the ContRoll active tilting system, which was installed in 1995 on a 25-year-old VT614 train operated by German Railways to test its retrofit applicability. Sintef Instrumentation in Oslo, Norway, supplied the electronic components for this first testing version of ContRoll. The system can be used for both high-speed trains and conventional railcars.

"The VT614 was originally designed to tilt approximately 4 degrees via air springs, but never operated as a tilting train," said Heiko Hofkamp, a mechanical engineer and project manager for Talbot"s Bogie Department. "Talbot engineers retrofitted this train set with new bogies equipped with the hydraulic tilting cylinders that are connected by an antiroll bar."

The first passenger car of the VT614 is equipped with the gyroscopes and accelerometers needed to measure the lateral acceleration caused by entering a curve. These instruments send signals to a central computer that actuates the hydraulic cylinders with the aid of slave machines, tilting the cars to a maximum of 7 degrees. The retrofitted VT614 went through curves with a radius of 500 millimeters and maximum cant of 150 millimeters at 132 kilometers per hour, compared with 113 kilometers before ContRoll.

The retrofitted VT614, which was tested over a two-year period, now serves the Nuremberg area in southern Germany.