INTRO: Tilt troubles
Sir - The derailment of an ICE-T trainset in Berlin (RG 4.00 p212) was apparently caused by a sticking non-return valve, causing a hydraulic tilting actuator to block. As a result, the car body twisted and the bogie derailed. When the train was hauled away, the damaged coach derailed once more. Ironically, the valve in question did not form part of the Fiat-supplied tilting system. This component was installed later at the insistence of DBAG, to allow the use of quick release connectors between car body and bogies, facilitating maintenance. Reinstalling the original flex connections quickly brought the trains back into operation.
The latest mishap with the VT611 DMUs you referred to concerns the modification of an auxiliary drive mounting. True, these tilting trainsets have been beset by a number of technical problems, requiring extensive and very costly modifications. The ultra-short delivery time and very low price specified by the operator certainly played a role in this.
In contrast, the AEG Neicontrol-E tilting system, the first to use an electromechanical actuator, has always performed well. The VT612 tilting DMUs now entering service are so equipped and from the beginning have demonstrated trouble-free running.
Cor A Legro