Dieselisation
Weighing against the cost of, and inertia against, replacing the large investment that railroads had in existing steam power were the dramatic increases in flexibility and efficiency with diesel. The fastest and most powerful steam locomotives were faster and more powerful than diesels; however, their range of efficient operation was severely limited. Diesels pro-rate their fuel usage to the length of trains, which a steam engine cannot do. Multiple-unit diesel power is scalable to power requirements with one locomotive crew; steam power is not. A high speed Hudson steam locomotive is good for only one situation, high speeds on level grades. The diesel locomotive can be operated by a single person, with no need of a fireman to run the boiler (two person cab crews may be required for other reasons). Also, diesels use much less fuel and no manpower when idling, something locomotives often do. Diesels can be parked running for days unattended, whereas steam engines must be constantly tended to if not completely shut down. Bringing a steam engine boiler up to operating temperature is often regarded as both an art and science, requiring much training and experience. A diesel is much simpler to start and shut down.
Lancaster and Chester Railroad
In 1946, the L&C upgraded its fleet by buying six diesel locomotives from the U.S. Army. These 65-ton Whitcomb locomotives had seen service in Italy during the war and burned about the same amount of oil to run that the old steam engines used for lubrication. The purchase of these engines made the L&C the first fully diesel-operated railroad in the state, something that Springs liked to boast of. The steam engines formerly used by the railroad were either sold or put out to pasture. However, these diesels did not spend long on the line as they were replaced by three 70-ton GEs in late 1950. Among the Whitcombs, number 51 passed to the Allegheny and South Side Railway where it would stay until the end of that property.