6 ms·

Quite remarkable. Too ahead of its time? Wonder why it never got revisited

by Fervicus 3y ago

modeless 3y ago
Seems like the requirement for gyroscopes in every car would be a deal breaker.
- neom 3y ago
  Could you make a gyro car? Akin to a locomotive? I don't exactly know how it would work but I was thinking we have locomotives so we don't need to put engines in every car. The thing I'm thinking about is that the gyro is kinda both a measurement device in a way, and also the system that actuates. Could these systems be separated, simplified, and scaled-down? I don't know, I'm not an engineer, just thinking aloud. :)
  - jerf 3y ago
    With the technology of the time I do not believe there is a solution. Modern technology might be able to turn the car couplings into something that can actively manage their tilt relative to each other, thus allowing them to propagate the balance beyond a single gyro car, but there's a lot of PID-controller-type [1] math that would go into determining if this was even possible with real, physical objects trying to control things the size and mass of train cars in a train track environment. The computations are probably not that difficult in 2024 but trying to actually deliver the correct forces in a timely manner may be difficult if not impossible. There aren't always solutions, or practical solutions, to the PID equations in the real world. Plus, I'm sitting here imagining the size of the electric motors we're trying to torque the cars against each other with and it's hard not to say that we're better off just having two tracks and putting those motors on the wheel themselves. (Which then collapses to having a locomotive setup like we have now.) In the "power/control/price" triangle we're basically forced to take the max on power and control, so these are going to be ferociously expensive if they can be built at all. And there's some bad failure cases that I just don't know that you can mitigate. Having 30 minutes after power loss to evacuate passengers is generally going to be enough, but cargo can't be evacuated on that timeline. And that's not the only failure case. A seized gyro is going to be catastrophic and even a single one could take the whole train down, even with that PID control system (which is going to be a stretch even without also having to build in buffers for failed gyros). The fact that a 2-track-train can just sit there for extended periods of time with no power is one of those advantages you don't even think about until you try to take it away. Guy was a genius though. It's basically an analog computer that keeps itself upright that you can ride. The final design is amazing with its judo-esque approach to using physics against itself. But I don't think it can be scaled up much beyond "neat tourist attraction". I'd ride one as a tourist attraction, though. [1]: https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%...
    - neom 3y ago
      Can always count on you for a fantastic reply Jeremy. Thank you. Indeed, the more I think on it the more difficult the edge cases seem, I hadn't even gotten to the power out thing, although from thinking on the spinning cube conversations in this thread[1], I had thought about magnets as a failsafe mechanism, but at that point.... "The fact that a 2-track-train can just sit there for extended periods of time with no power is one of those advantages you don't even think about until you try to take it away." <- This heh. [1] https://news.ycombinator.com/item?id=39336139 https://news.ycombinator.com/item?id=39336139
meche123 3y ago
Because you have to replicate the same complicated mechanism for all the cars. Moreover, if a gyro in one of cars malfunctions the whole train is at risk. Another problem is that the system is reactive, meaning that there is a lot of shaking and balancing that is quite unacceptable - think about drinking a cup of tea in such a wobbly train even on straight lines, while on curves it's not staying horizontal by design. Yet another problem is that it can't share the current infrastructure without major switch changes while sharing the infrastructure the other way around is impossible. And in the end all of this effort for trying to fix a problem that doesn't really exist, at least not in Europe where most of the rail infrastructure was already built 100 years ago.
- Reason077 3y ago
  > ”while on curves it's not staying horizontal by design” Worth noting that modern tilting trains do this quite successfully (on two rails!), in order to run faster on tracks with tight curves. By “leaning in” to curves, you make the ride more comfortable, not less. Tilting trains are used extensively on the UK’s West Coast Main Line, for example.
  - danhor 3y ago
    > By “leaning in” to curves, you make the ride more comfortable, not less. That is the intention, but many people report discomfort due to the non-ideal adjustments, at least for the tilting trains in germany.
    - philjohn 3y ago
      I'm one of those people. I commute 50 mins each way on a Pendolino in the UK (into and out of London) and find that if I'm doing work on my laptop, or responding to emails on my phone as the train tilts I feel uncomfortable and dizzy. The "slow" Desiro trains that don't tilt take 2 minutes longer to get into London, because whilst their top speed is 15Mph lower they accelerate faster.
      - 3y ago
1letterunixname 3y ago
No. Watch the video.
woah 3y ago
What's the benefit?
- joshuaheard 3y ago
  In the video it explains it only uses half the track material since it only has one track instead of two. It can also go faster since it leans into corners and doesn't derail like two track trains.
  - kbenson 3y ago
    It also required the complex gyro for each car, not just the engine, which is why the video states ultimately it was killed. I'm not sure the situation has changed with that.
  - p1mrx 3y ago
    > leans into corners Modern trains do that too. https://en.wikipedia.org/wiki/Advanced_Passenger_Train https://en.wikipedia.org/wiki/Advanced_Passenger_Train eventually led to https://en.wikipedia.org/wiki/Avelia_Liberty https://en.wikipedia.org/wiki/Avelia_Liberty, which is being deployed for Acela in the US.
kevin_thibedeau 3y ago
The double flange wheel wouldn't work with existing rail switches.

Quite remarkable. Too ahead of its time? Wonder why it never got revisited

modeless 3y ago

Seems like the requirement for gyroscopes in every car would be a deal breaker.

neom 3y ago
Could you make a gyro car? Akin to a locomotive? I don't exactly know how it would work but I was thinking we have locomotives so we don't need to put engines in every car. The thing I'm thinking about is that the gyro is kinda both a measurement device in a way, and also the system that actuates. Could these systems be separated, simplified, and scaled-down? I don't know, I'm not an engineer, just thinking aloud. :)
- jerf 3y ago
  With the technology of the time I do not believe there is a solution. Modern technology might be able to turn the car couplings into something that can actively manage their tilt relative to each other, thus allowing them to propagate the balance beyond a single gyro car, but there's a lot of PID-controller-type [1] math that would go into determining if this was even possible with real, physical objects trying to control things the size and mass of train cars in a train track environment. The computations are probably not that difficult in 2024 but trying to actually deliver the correct forces in a timely manner may be difficult if not impossible. There aren't always solutions, or practical solutions, to the PID equations in the real world. Plus, I'm sitting here imagining the size of the electric motors we're trying to torque the cars against each other with and it's hard not to say that we're better off just having two tracks and putting those motors on the wheel themselves. (Which then collapses to having a locomotive setup like we have now.) In the "power/control/price" triangle we're basically forced to take the max on power and control, so these are going to be ferociously expensive if they can be built at all. And there's some bad failure cases that I just don't know that you can mitigate. Having 30 minutes after power loss to evacuate passengers is generally going to be enough, but cargo can't be evacuated on that timeline. And that's not the only failure case. A seized gyro is going to be catastrophic and even a single one could take the whole train down, even with that PID control system (which is going to be a stretch even without also having to build in buffers for failed gyros). The fact that a 2-track-train can just sit there for extended periods of time with no power is one of those advantages you don't even think about until you try to take it away. Guy was a genius though. It's basically an analog computer that keeps itself upright that you can ride. The final design is amazing with its judo-esque approach to using physics against itself. But I don't think it can be scaled up much beyond "neat tourist attraction". I'd ride one as a tourist attraction, though. [1]: https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%...
  - neom 3y ago
    Can always count on you for a fantastic reply Jeremy. Thank you. Indeed, the more I think on it the more difficult the edge cases seem, I hadn't even gotten to the power out thing, although from thinking on the spinning cube conversations in this thread[1], I had thought about magnets as a failsafe mechanism, but at that point.... "The fact that a 2-track-train can just sit there for extended periods of time with no power is one of those advantages you don't even think about until you try to take it away." <- This heh. [1] https://news.ycombinator.com/item?id=39336139 https://news.ycombinator.com/item?id=39336139

meche123 3y ago

Because you have to replicate the same complicated mechanism for all the cars. Moreover, if a gyro in one of cars malfunctions the whole train is at risk. Another problem is that the system is reactive, meaning that there is a lot of shaking and balancing that is quite unacceptable - think about drinking a cup of tea in such a wobbly train even on straight lines, while on curves it's not staying horizontal by design. Yet another problem is that it can't share the current infrastructure without major switch changes while sharing the infrastructure the other way around is impossible. And in the end all of this effort for trying to fix a problem that doesn't really exist, at least not in Europe where most of the rail infrastructure was already built 100 years ago.

Reason077 3y ago
> ”while on curves it's not staying horizontal by design” Worth noting that modern tilting trains do this quite successfully (on two rails!), in order to run faster on tracks with tight curves. By “leaning in” to curves, you make the ride more comfortable, not less. Tilting trains are used extensively on the UK’s West Coast Main Line, for example.
- danhor 3y ago
  > By “leaning in” to curves, you make the ride more comfortable, not less. That is the intention, but many people report discomfort due to the non-ideal adjustments, at least for the tilting trains in germany.
  - philjohn 3y ago
    I'm one of those people. I commute 50 mins each way on a Pendolino in the UK (into and out of London) and find that if I'm doing work on my laptop, or responding to emails on my phone as the train tilts I feel uncomfortable and dizzy. The "slow" Desiro trains that don't tilt take 2 minutes longer to get into London, because whilst their top speed is 15Mph lower they accelerate faster.
    - 3y ago

1letterunixname 3y ago

No. Watch the video.

woah 3y ago

What's the benefit?

joshuaheard 3y ago
In the video it explains it only uses half the track material since it only has one track instead of two. It can also go faster since it leans into corners and doesn't derail like two track trains.
- kbenson 3y ago
  It also required the complex gyro for each car, not just the engine, which is why the video states ultimately it was killed. I'm not sure the situation has changed with that.
- p1mrx 3y ago
  > leans into corners Modern trains do that too. https://en.wikipedia.org/wiki/Advanced_Passenger_Train https://en.wikipedia.org/wiki/Advanced_Passenger_Train eventually led to https://en.wikipedia.org/wiki/Avelia_Liberty https://en.wikipedia.org/wiki/Avelia_Liberty, which is being deployed for Acela in the US.

kevin_thibedeau 3y ago

The double flange wheel wouldn't work with existing rail switches.