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has several things in its favor. Because of its swivel-truck construction the 110-ton diesel-electric will negotiate sharper curves than, and meet the same weight limitations as, the steamer with its 90-ton rigid wheelbase and, therefore, can replace it. The extra 20-tons adhesive weight and the smoother torque of the electric drive mean higher accelerating tractive effort below about five mph for the diesel-electric than for the steam locomotive. The steam units, although nominally rated 1500 cylinder hp, does not develop its full rating until it reaches a speed of about 20 mph whereas the diesel-electric develops its full hp from about three mph on up through the entire switching range of speed. From standstill up to 10 mph the [[underlined]] average [[/underlined]] driver horsepower of the steam unit does not exceed that of the diesel-electric. The result is that up to five mph the faster acceleration of the diesel-electric unit, due to its greater driver weight and higher available adhesion, balances off what advantage the steam unit may have from 5 to 10 mph. Owing to the maximum speed limitation of 8 to 10 mph, the steam locomotive never can get up to speeds where its greater horsepower would allow it to walk away from the diesel-electric unit.

There are a few other factors which enter this picture but do not materially change it. Because the steam locomotive always has the tender to brake with in addition to the locomotive proper, the braking of the steam unit is somewhat more effective than that of the diesel-electric. The fact that the tender brakes, to be safe, should be based on the light weight of the tender and that the diesel-electric weighs more than the steam locomotive alone, tend to brong the braking rates very nearly in line. Moreover, the tender when loaded is a constant burden on the steam unit since it will be equivalent to one or two extra cars over the diesel-electric's gross weight. And, whereas the diesel-electric has its full horsepower constantly available, the steam locomotive may not have its full power ready for action depanding upon the steam pressure and the condition of the fire; in fact, the tendency frequently is to run a low fire to avoid excessive popping off of steam during the large portion of a total switching time that is spent with the throttle closed. In many typical switching assignments, this so-called idling time is in the neighborhood of 70 per cent of the total assigned time.

In actual practice, where 600-hp 100-ton diesel-electric locomotives have replaced six-wheel steam switchers, almost invariably their performance is judged by railroad men to be faster than that of the steam units. One immediate manifestation of this is the deep satisfaction the engineer expresses for his new found ability to "run the pants" off the ground crew.
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Transcription Notes:
"brong the braking rates" in the middle of the page is obviously a typo for "bring the braking rates" but I left it as typed. The same is true of the obvious typo "depanding upon the steam" in the same paragraph.--thomasc