tilting train

A tilting train is a train that has a mechanism enabling increased speed on regular rail tracks. As a train (or other vehicle) rounds a curve at speed, it experiences centripetal force, pushing on objects inside it. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest, and standing passengers to lose their balance. The train can physically tilt on one side, eventually causing it to derail. Tilting trains are designed to counteract this by tilting the carriages towards the inside of the curve. The train may be constructed such that inertial forces cause the tilting (passive tilt), or it may have a computer-controlled powered mechanism (active tilt).

The first passive tilting car design was built in the United States in 1937, and an improved version was built in 1939. The beginning of World War II ended development. Talgo introduced a version based on their articulated bogie design in 1950s, and this concept was used on a number of commercial services. Among these was the UAC TurboTrain, which was the first (albeit short-lived) tilting train to enter commercial service in 1968 in the US and Canada. Japan similarly experimented, from the late 1960s, through the 591 Series that developed into the highly successful Hitachi 381 series, that has been in service since 1973. In parallel, Fiat Ferroviaria produced the experimental Y 0160 in 1970, that would evolve into the Pendolino family, in 1976, and operated in 11 countries. All of these had problems with short curves like those in switchyards, where they tended to sway about. Also, because of the way the carriages always swung outward, they placed more weight on the outside of the curve, which limited their improvement in cornering speed to about 20%.