Diesel locomotive advantages over steam locomotives
Diesel locomotive engines slowly started to overtake those powered by steam as the manufacturing and operational efficiencies of the former made them cheaper to own and operate.
While initial costs of diesel engines were high, steam locomotives were custom-made for specific railway routes and lines and, as such, economies of scale were difficult to achieve.
Though more complex to produce with exacting manufacturing tolerances of 1/10,000th of an inch vs. 1/100th of an inch for steam engines, diesel locomotive parts were easier to mass production.
Steam locomotive manufacturer Baldwin offered almost five hundred steam models in its prime, other diesel manufactures offered fewer than ten diesel varieties.
Diesel vs.steam locomotive
Diesel locomotive offered significant operating advantages over steam locomotives. They can safely be operated by one person, making them ideal for switching/shunting duties in yards and the operating environment is much more attractive, being much quieter, fully weatherproof and without the dirt and heat that is an inevitable part of operating a steam locomotive.
Diesel engines can be started and stopped almost instantly, meaning that a diesel locomotive has the potential to incur no costs when not being used. Steam locomotives require intensive maintenance, lubrication and cleaning before, during and after use.
Steam locomotive preperation took many hours, especially if the locomotive is being fired from cold. However, it is still the practice of large North American railroads to use straight water as a coolant in diesel engines instead of coolants that incorporate anti-freezing properties.
This resulted in diesel engines being left idling when parked in cold climates instead of being completely shut down. Still, a diesel engine can be left idling unattended for hours or even days, especially since practically every diesel engine used in locomotives has systems that automatically shut the engine down if problems such as a loss of oil pressure or coolant loss occur.
A steam locomotive, by comparison, may be kept in readiness between uses with a small fire to maintain a slight heat in the boiler, but requires regular and frequent attention to maintain the fire and the level of water in the boiler.
Moreover, maintenance and operational costs of steam locomotives were much higher than diesel counterparts even though it would take diesel engines almost 50 years to reach the same horsepower output that steam locomotives could achieve at their technological height.
Annual maintenance costs for steam engines accounted for 25% of the initial purchase price. Spare parts were machined from wooden masters for specific locomotives. The sheer number of unique steam engines meant that there was no feasible way for spare-part inventories to be maintained.
Steam engines also required large quantities of coal and water, which were expensive variable operating costs. Further, the thermal efficiency of steam was considerably less than that of Diesel engines.
Dieselís theoretical studies demonstrated potential thermal efficiencies for a compression ignition engine of 36% compared with 6-10% for steam locomotives, and an 1897 one-cylinder prototype operated at a remarkable 26% efficiency. By the middle of the twentieth century, Diesel engines had effectively replaced steam engines.
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