These heavy tank locomotives were developed for local service in the Boston area. Due to the tank locomotive design rarely used in the USA, they could run in both directions at high speed. A three-axle rear bogie was used to carry sufficiently large supplies. This led to the 4-6-6T wheel arrangement, which had previously only been used on smaller Mason Bogie locomotives.

In normal operation they often pulled ten steel cars and were apparently able to move up to 20 of these cars with sufficient acceleration. They were regarded as successful all-purpose locomotives, but were only used in the Boston area due to the small number of units. They bore the markings of New York Central for most of their lives. When they were replaced by diesel locomotives in their traditional area of application around 1950, no new purpose was found, so they were probably scrapped in a timely manner.