7 ms·

Magnetic (eddy current) brakes work by converting kinetic energy into heat, which doesn't really solve the problem here. I'm not sure if anyone has devised a sy

Magnetic (eddy current) brakes work by converting kinetic energy into heat, which doesn't really solve the problem here. I'm not sure if anyone has devised a system that actually captures electrical energy from the braking action, or if such a thing is even plausible.

bushbaba 4y ago
It'd at least solve the dust break-pad dust issue
zorlack 4y ago
You could put the braking resistors above ground, no? Or if the braking resistors have to be close the the coils, then you could use a heat-exchanger to move the heat somewhere else...
jamincan 4y ago
Regenerative braking generates electricity and there's really no reason modern trains wouldn't use them. Another approach that can be used when initially building the system is to have a slope leading into/out of stations so that energy can be stored as gravitional potential. I know the Montreal Metro was built this way.
- dtgriscom 4y ago
  Your second point was stated exactly in the parent of your parent comment.
  - jamincan 4y ago
    I don't think that's correct. @pbhjpbhj talks about magnetic braking and some sort of pneumatic braking. The sibling to his comment by @fredley mentions it, but I don't recall seeing that yet when I posted mine.
namibj 4y ago
Yes. It's called "electric generator" and can be performed by almost all electric motors.
- tialaramex 4y ago
  Indeed. Electricity and magnetic fields are so closely related we have a single term, electromagnetism, the motor and generator are thus almost the same thing and it's relatively easy to build a single device which can serve both purposes. Actually regenerative braking is common on electric trains. Stock bought since at least the 1990s for London Underground has regenerative braking of various forms, with the more modern being fitted to S-stock (the sub-surface lines which were all gradually replaced with a single type of train, if you went on a "Tube" train and it was actually walk-through the length of the train and seemed vaguely modern inside, that was S-stock and you weren't in the deep tube where heat is a bigger problem) In the 1970s when the oldest stock still in use was purchased, regenerative braking was not a thing.
  - hakfoo 4y ago
    Regenerative braking was a thing for decades before the 1970s. Some old freight routes used electric haulage because the regenerative braking going downhill almost completely offset the electricity consumption going uphill.

bushbaba 4y ago

It'd at least solve the dust break-pad dust issue

zorlack 4y ago

You could put the braking resistors above ground, no? Or if the braking resistors have to be close the the coils, then you could use a heat-exchanger to move the heat somewhere else...

jamincan 4y ago

Regenerative braking generates electricity and there's really no reason modern trains wouldn't use them. Another approach that can be used when initially building the system is to have a slope leading into/out of stations so that energy can be stored as gravitional potential. I know the Montreal Metro was built this way.

dtgriscom 4y ago
Your second point was stated exactly in the parent of your parent comment.
- jamincan 4y ago
  I don't think that's correct. @pbhjpbhj talks about magnetic braking and some sort of pneumatic braking. The sibling to his comment by @fredley mentions it, but I don't recall seeing that yet when I posted mine.

namibj 4y ago

Yes. It's called "electric generator" and can be performed by almost all electric motors.

tialaramex 4y ago
Indeed. Electricity and magnetic fields are so closely related we have a single term, electromagnetism, the motor and generator are thus almost the same thing and it's relatively easy to build a single device which can serve both purposes. Actually regenerative braking is common on electric trains. Stock bought since at least the 1990s for London Underground has regenerative braking of various forms, with the more modern being fitted to S-stock (the sub-surface lines which were all gradually replaced with a single type of train, if you went on a "Tube" train and it was actually walk-through the length of the train and seemed vaguely modern inside, that was S-stock and you weren't in the deep tube where heat is a bigger problem) In the 1970s when the oldest stock still in use was purchased, regenerative braking was not a thing.
- hakfoo 4y ago
  Regenerative braking was a thing for decades before the 1970s. Some old freight routes used electric haulage because the regenerative braking going downhill almost completely offset the electricity consumption going uphill.