27. Small, low-cost pneumatic centering cylinder for tilting trains
The number of active tilting trains with air-springs which do not require special bogie structures has increased over the past few years, in an attempt to improve ride comfort on board trains running through curves.
However, tilting trains with air-springs undergo greater lateral displacement in curves than pendulum trains, which in turn have been blamed for lower ride comfort due to the impact on lateral bump stops.
Consequently, a centering cylinder (Figure 1) has been developed to control the lateral movement of carbodies. The centering cylinders are fitted parallel to the lateral dampers on the bogie (Figure 2), and exert a restoring force to counter lateral displacement, thereby controlling the lateral movement of the carbody and reducing impact on the lateral bump stops.
Even though the driving force of the cylinder uses compressed air, the valve mechanism controlling the air supply to the cylinder is mechanically built into the piston-rod part of the cylinder, and therefore no separate controller nor sensor are required, keeping the size and cost of the device to a minimum.
The results of running tests on conventional line express trains demonstrated that lateral vibrations of around 2 Hz produced by impact on the lateral bump stops, fell (Figure 3), and that the lateral ride quality level (LT) in successive curved sections could be improved with a reduction of approximately 2-4 dB (Figure 4).
This device can be used not only on air-spring tilting trains, but as an improvement measure on any trains where the effect of lateral bump stops on ride comfort in curved sections is proving to be a problem.