Abstract
Modern civilization is based on transportation, and the fundamental prime mover in transportation is the steam locomotive. Improvements in the steam locomotive affecting its efficiency and reliability are reflected in a corresponding manner in the entire transportation industry. The loads and stresses developed in locomotive service on bearings are exceptionally severe, and the consequences of failure are far reaching, and these conditions together have militated against rapid introduction of the roller bearing in locomotive service. The application of the roller bearing in passenger service has progressed in an encouraging manner over a period of years, but efforts to interest railroad men in application of roller hearings to a complete locomotive were unsuccessful, and finally convinced the Timken company of the desirability of building a locomotive equipped on all wheels with roller bearings and loaning it for an extended period of service to the railroads of the United States. The Timken locomotive was designed for application of Timken bearings on all of the drivers, engine-truck, trailer, and tender-truck wheels, on the Franklin booster, and on various elements of the control mechanism. The introduction of roller bearings on the drivers permits of higher rotative speeds, as the bearings surround the drivers completely, and eliminates pounds within the bearing boxes. Heating is eliminated, as the temperature rise does not exceed 25 deg above atmosphere. The wheel diameter was therefore selected between that prevailing for modern high-speed freight locomotives, averaging 70 in., and high-speed passenger locomotives, with 80-in. drivers. The economy in friction, estimated at 12 to 15 per cent, was utilized in increasing the diameter of the drivers over that of the modern freight locomotive, and developing through the saving in friction a drawbar capacity equivalent to the latter. The 73-in. wheel was therefore selected. The 4-8-4 wheel arrangement with four-wheel trailer truck was favored.