Diesels have one advantage over steam, they develop a lot of tractive effort
in the 0 to 1 mph speed range. After that it drops as the speed increases.
Steam is the opposite, the fact is the faster they go the more power they
develop. That's one reason three AC4400CW's can move a 10,000 ton freight
There was a saying that went something like – a diesel can lift a train a steam
engine can’t and steam engine can pull a train a diesel can lift.
The price to replace steam compared to diesels was pretty much even. To get
the same pulling
Theoretically a steam engine has no limit on the amount of horsepower it can
generate. In practicality the limit is the amount of steam the boiler can
produce. Hence a typical rating for a steam engine was boiler horsepower
rather than draw bar horse power.
However, I admit, the diesel was the right machine for the times. Many
railways back then were moving to slow high tonnage freights and that isn’t
compatible with the steam engine’s performance specifications.
Jeff
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