I wouldn't have expected that those retarder would make much difference to the speed of a train weighing several thousand tonnes.
Probably not on a train under power, but if enough of them are mounted throughout a railway switching yard they would slow or deter roll offs from missed couplings
Never try to tell me it can't be done
When I have to paint I use KBS products
Although it is not intuitional , there is a smallll amount of kinetic energy displaced with each action, but it must take a lot of them to reduce speed measurably.
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