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One thing the article doesn't mention is that the trains are more efficient because they use regenerative braking, rather than friction brakes. The friction bra
by rjmunro 3y ago
One thing the article doesn't mention is that the trains are more efficient because they use regenerative braking, rather than friction brakes. The friction brakes cause a lot of the heat and dust in the underground.
By eliminating this heat, they are able to use that heat budget to run air conditioners on the trains and they still make less heat overall. As a side effect, the dust should be reduced too (and probably a bit of the maintenance)
- rob74 3y agoThere is actually an intermediate step between "friction brakes" and "regenerative braking" - electric trains can use the engines to brake, but the current produced is then fed to resistors, which dissipate it as heat, rather than used to charge a battery or to feed it back into the power supply line - https://en.wikipedia.org/wiki/Dynamic_braking#Rheostatic_braking https://en.wikipedia.org/wiki/Dynamic_braking#Rheostatic_bra.... So the friction brakes are actually only used when maximum braking is required - and these will also be needed with regenerative braking. Using regenerative instead of rheostatic braking will however lower the amount of heat produced I guess...
- cpncrunch 3y agoThe 1973 trains already used rheostatic braking. The new ones use regenerative braking. https://www.modernrailways.com/article/revolution-piccadilly-line#:~:text=This%20is%20because%20the%20new,this%20is%20some%20way%20off https://www.modernrailways.com/article/revolution-piccadilly.... http://www.trainweb.org/tubeprune/73%20tube%20stock.htm http://www.trainweb.org/tubeprune/73%20tube%20stock.htm