3 ms·

No, the modern inverter electric locomotives can break to zero with the motor just fine, they just lack a sensor to accurately measure speed and their motors ta

by namibj 5y ago

No, the modern inverter electric locomotives can break to zero with the motor just fine, they just lack a sensor to accurately measure speed and their motors take, at these ultra-low-speeds, a "desired torque" value, not a "desired RPM" value. You still want friction breaks to hold you in place once you've stopped, but there's no strict need to use them earlier. Yes, current controllers may not be intelligent enough, but that should be fixeable without changing the power electronics, and only replacing their controller.

mschuster91 5y ago
Lot of the rolling stock is 40 years and older though, with new locos costing millions of dollars apiece it takes lots of time to modernize fleets. Europe still uses screw and hook/buffers for that reason, and it took well over a decade to mandate silent composite brakes.
- namibj 5y ago
  Yeah, rolling stock is old. Also, in Germany the DB Class 120 locos (the first series-production 3-phase inverter electric locos) were retired between 2016 and 2020 (build during the 80's). Even the older non-inverter locos here use electro-dynamic brakes (afaik for economic/control reasons, as they are better than air for keeping speed during downhill sections under control), and the remaining ones will retire soon. The screw and hook/buffers issue is more due to the distributed ownership of the freight cars, and early issues with certification of adapters between UIC central couplers and screw+hook/buffers. Sure, there are situations where it's too steep to only brake the loco, but they aren't that common and adding some induction brakes to some of the heavier cars and preferentially using them shouldn't be particularly expensive. Sure, not cheap, but also not prohibitive for getting rid of friction breaks in the course of normal operation (well, some friction breaking may be needed from time to time to keep them in check and verify proper function.... but still a >90% reduction shouldn't be hard.

by namibj 5y ago

mschuster91 5y ago

Lot of the rolling stock is 40 years and older though, with new locos costing millions of dollars apiece it takes lots of time to modernize fleets. Europe still uses screw and hook/buffers for that reason, and it took well over a decade to mandate silent composite brakes.

namibj 5y ago
Yeah, rolling stock is old. Also, in Germany the DB Class 120 locos (the first series-production 3-phase inverter electric locos) were retired between 2016 and 2020 (build during the 80's). Even the older non-inverter locos here use electro-dynamic brakes (afaik for economic/control reasons, as they are better than air for keeping speed during downhill sections under control), and the remaining ones will retire soon. The screw and hook/buffers issue is more due to the distributed ownership of the freight cars, and early issues with certification of adapters between UIC central couplers and screw+hook/buffers. Sure, there are situations where it's too steep to only brake the loco, but they aren't that common and adding some induction brakes to some of the heavier cars and preferentially using them shouldn't be particularly expensive. Sure, not cheap, but also not prohibitive for getting rid of friction breaks in the course of normal operation (well, some friction breaking may be needed from time to time to keep them in check and verify proper function.... but still a >90% reduction shouldn't be hard.