The H-24-66 is a diesel electric locomotive manufactured by the Fairbanks-Morse company. Produced between 1953 and 1957, these six-axle, 2,400 horsepower road switchers were commonly known as Train Masters. Touted by Fairbanks-Morse as "...the most useful locomotive ever built...", it used a unique opposed piston designed engine. At the time of production, the Train Master was the most powerful single-engine diesel locomotive available at the time and was legendary for its pulling power and rapid acceleration. While some railroads saw advantages in the Train Master's greater power, the perception on the part of others that the unit had too much horsepower (coupled with the difficulties inherent in maintaining the opposed-piston engine, inadequacies in the electrical system, and a higher-than-normal consumption of cooling water) contributed to poor marketplace acceptance of the Train Masters. Perhaps it was simply ahead of its time, as no competitor offered a locomotive with an equal horsepower rating until several years later.

Lionel’s version of the FM Train Master is an excellent model of the real life counterpart. With dual motors and several premium features, all Train Mater models have been well received by collectors and operators over the past half century and remain in demand today.