Various efforts have been made to apply the internal-combustion engine to self-propelled rail-cars. The greatest development along this line prior to the war was in connection with the McKeen and General Electric cars that were built from 1906 to 1914. The builders of those cars were greatly handicapped by the lack of available experience in connection with the design of gasoline engines, particularly of the larger type. Since the war a gradual development of rail-cars has taken place, starting with small converted motor trucks and gradually increasing in size and adaptability to the service, until now gasoline-electric cars of 250 hp. and about 75 ft. in length are available, while mechanically driven cars are available up to 190 continuous horsepower.
Each of the various drives that have been proposed, including hydraulic, electric and mechanical, has various advantages, but it seems probable at the present time that the gasoline-electric system will be used generally in cars of extremely large size, while the straight mechanical drive will be preferable for cars up to about 200 hp. The advantages and disadvantages of the different types of drive are given and the service conditions and design requirements to be met by rail-car construction are listed in this paper. The gasoline rail-car must be designed for utmost reliability, durability and simplicity of operation and maintenance. The powerplant and transmission design and the work characteristics of the largest present mechanically-driven rail-car are described and its operating costs as compared with those of light steam trains are given. Cars of this type fill a distinct economic field between the highway motorcoach and the steam locomotive and train. A limited potential market for the sale of about 230 to 250 cars per year exists.