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One minor correction. Tilt trains exist to allow higher speed service on older lines where tipping would be a safety problem. They can run just fine with the ti

One minor correction. Tilt trains exist to allow higher speed service on older lines where tipping would be a safety problem. They can run just fine with the tilt mechanism disabled, provided they go at the lower speed of the older trains.

avianlyric 4y ago
> Tilt trains exist to allow higher speed service on older lines where tipping would be a safety problem. That isn’t true. No train network is going to allow train to operate at speed, if the safety of those trains depends on non-failure of a complex tilting mechanism. Having a tilting mechanism fail or jam before a corner (which has happened) can not result in a high speed derailment. That risk is simply unacceptable on modern railway. Tilting trains make it possible to run at higher speeds on older lines by allowing older lines to have the camber on corners increased to accommodate the higher speeds. But the camber can’t increased enough to hit optimal amount of camber without make the rail unusable to older trains. Tilting trains provide a useful compromise. Increase the camber enough for stability (but not comfort), while keeping the camber acceptable for older trains, then make up the rest of the tilt with carriage tilting mechanism. The total amount of tilt is then comfortable for passengers. There is a minor safety element provided by tilting trains, in that lateral forces in cornering are lower, thus passengers are less likely to fall, and items won’t come of tables. But the tilting mechanism certainly is a safety critical element to running faster on old lines. It’s also worth mentioning that carriages on passenger trains have a pretty low center of gravity, as all the heavy equipment (motors, bogies, breaks, suspension) sits below the passenger compartment. As a result tilting a passenger train won’t significantly move its center of gravity, so impact on total train stability is going to pretty minor.
dredmorbius 4y ago
I'd always understood tilt trains to be a comfort factor rather than safety. Tilting a carriage isn't going to adjust the CoG by any appreciable amount. It will tend to make the net centripetal moment more virtical from the reference frame of passengers, however. Wikipedia's article corroborates this: As a train (or other vehicle) rounds a curve at speed, objects inside the train experience centrifugal force. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest, and standing passengers to lose their balance. Tilting trains are designed to counteract this by tilting the carriages towards the inside of the curve, thus compensating for the g-force. https://en.wikipedia.org/wiki/Tilting_train https://en.wikipedia.org/wiki/Tilting_train

avianlyric 4y ago

> Tilt trains exist to allow higher speed service on older lines where tipping would be a safety problem. That isn’t true. No train network is going to allow train to operate at speed, if the safety of those trains depends on non-failure of a complex tilting mechanism. Having a tilting mechanism fail or jam before a corner (which has happened) can not result in a high speed derailment. That risk is simply unacceptable on modern railway. Tilting trains make it possible to run at higher speeds on older lines by allowing older lines to have the camber on corners increased to accommodate the higher speeds. But the camber can’t increased enough to hit optimal amount of camber without make the rail unusable to older trains. Tilting trains provide a useful compromise. Increase the camber enough for stability (but not comfort), while keeping the camber acceptable for older trains, then make up the rest of the tilt with carriage tilting mechanism. The total amount of tilt is then comfortable for passengers. There is a minor safety element provided by tilting trains, in that lateral forces in cornering are lower, thus passengers are less likely to fall, and items won’t come of tables. But the tilting mechanism certainly is a safety critical element to running faster on old lines. It’s also worth mentioning that carriages on passenger trains have a pretty low center of gravity, as all the heavy equipment (motors, bogies, breaks, suspension) sits below the passenger compartment. As a result tilting a passenger train won’t significantly move its center of gravity, so impact on total train stability is going to pretty minor.

dredmorbius 4y ago

I'd always understood tilt trains to be a comfort factor rather than safety. Tilting a carriage isn't going to adjust the CoG by any appreciable amount. It will tend to make the net centripetal moment more virtical from the reference frame of passengers, however. Wikipedia's article corroborates this: As a train (or other vehicle) rounds a curve at speed, objects inside the train experience centrifugal force. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest, and standing passengers to lose their balance. Tilting trains are designed to counteract this by tilting the carriages towards the inside of the curve, thus compensating for the g-force. https://en.wikipedia.org/wiki/Tilting_train https://en.wikipedia.org/wiki/Tilting_train