The ever-increasing demands and distribu tion factors presenting themselves have resulted along with other things in increased train loads and as a result greater capacity in tractive effort. This increase has been met by con structing larger locomotives with greater steam ing capacity. The average locomotive is in service something less than 20 per cent of the time with an average daily mileage of about 80 miles. Considerable attention is being paid to the possibility of increasing the amount of time the locomotive is in active service. This of course means the changing of crews while the engine is doing useful work.
For the fiscal year ending 30 June 1914, 64,760 locomotives of all classes were in use in the United States as reported by the Inter state Commerce Commission. The total mile age was 1,755,972,325 miles, an average of 27, 115 miles per annum per locomotive.
Types. There are between 30 and 40 types of locomotives in use in the United States. divided between passenger, freight and switch ing. They are as a rule known and designated according to the number of wheels and drivers. The first figure denotes the number of lead ing wheels in the front truck or under the front; the second gives the number of drivers and the last the number of trailing wheels under the rear end. The following are some of the types now in use: The most common types in -railroad service are the 4-4-0 (American) ; 4-4-2 (Atlantic) , 2-6-0 (Mogul) ; 4-6-0 (10 wheeler) ; 2-6-2 (Prairie) 4-6-2 (Pacific) ; 2-8-0 (Consoli dated) ; 2-8-2 (Mikado); and 0-6-0 (6 coupled switching).
Each type is manufactured in different weights with various tractive efforts dependent to a certain extent upon the weight. The fol lowing table indicates the average range in weight: -- - always be given careful consideration. A thor ough knowledge should be had relative to the various fuels, their composition, condition of operation when using same, quantities required, cost, availability and education of crews oper ating the locomotive.
Wood. On logging railroads wood is al most universally used as a fuel for locomo tives. Approximately two and one-fourth pounds of dry wood are equivalent in heating value to one pound of soft or bituminous coal.
The average composition of several kinds of dry wood by weight is as follows: Types for Passenger Service. The 4-6-2, or Pacific type locomotive, is best suited for the present-day demands in fast passenger service. It is used to a considerable extent where a tractive effort of 40,000 to 45,000 pounds is required. Where long heavy trains are operated or where extra heavy grades are prevalent, the Mountain type of locomotive, or 4-8-2, is growing in favor. The Atlantic, 4-4-2, and the Prairie, 2-6-2, are used exten sively on the shorter runs or where local opera tion prevails.
Types for Freight Service. It was but a few years ago that the Consolidation, 2-8-0, locomotives comprised about 30 per cent of the locomotives in use. For heavy freight service and for fast trains it is being replaced by the heavier type of Mikado or 2-8-2. The Mikado is used mainly where the tractive ef fort required is about 55,000 pounds. For heavier service and up to 83,000 pounds trac tive effort, the Santa Fe, 2-10-2, is becoming popular. The Fe appears to give better results for heavy slow service than either the Consolidated or Mikado. Where the service is exceptionally heavy the Mallet articulated types of locomotives are growing in favor. These engines are built with tractive efforts ex ceeding 100,000 pounds. The Mallet articu lated compound locomotive was used in some of the mountainous districts of Europe prior to such modifications as were necessary to adapt it to requirements set by the railroads of this country. Practically two locomotives, considering the drivers and cylinders, are com bined. It has one boiler and one furnace and lends itself to a more advantageous application of the compounding principle.
Types for Switching Service.The 0-6-0 type is the most common type of switch engine. Occasionally the Mallet 0-8-8-0 is used with a tractive effort of 100,000 pounds. A type more commonly found, however, than the 0-8-8-0 for heavy switching is the 0-8-0, espe cially where the tractive effort required is about 70,000 pounds.