Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

309. The classification of locomotives should be determined according to the following relations.

Department depends upon commercial duty.

Division depends upon character of road.

Order depends upon weight of trains.

Class depends upon speed of trains.

Note.—The general classification is given at the end of this chapter.

High rates of speed are generally combined with light loads, and heavy trains are required to move at the lower velocities.

Great speeds require the rapid production and consumption of a large bulk of steam of but little density; large wheels and short stroke, that the ratio of velocities of piston and wheel may be as great as possible.

Heavy trains consume less steam by bulk, per mile, but of a much greater density, and combine a long stroke with a small wheel, by which great leverage is obtained.

In general, engines for winter use should be heavier than those for summer, upon the same ground, as natural causes are more liable to resist adhesion in the winter.