Atlantic Coast Line 4-4-2

The advantages of the 4-4-2 design included a large boiler and a firebox of "desirable form" with "ample depth and width" which could be fitted over the rear frames,^[2] and this design for the first to exploit those features.^[1] There were also claimed of improved riding compared to some other types.^[2] The design specification called for the ability to haul a ten-coach train up a 32 foot grade (1% or 1 in 165) at 40 mph (64 km/h).^[1]

The initial batch of five were constructed in 1894/5.^[1] Further members classified as Class I/I-2 were built and the final two classified class I-3 were constructed in 1900.^[1]

The class was introduced to the constituent companies operating the ACL brand from 1894-1895.^[2]

The adoption of the name Atlantic for the class and subsequently the 4-4-2 wheelbase arrangement itself derives from name of the railroad they were supplied to.^[2] The advantages of the "Atlantic" type led to several other designs around the start of the twentieth century adopting the 4-4-2 wheelbase for express passenger work including the Milwaukee Road class A2, Pennsylvania Railroad class E1, as well as several railroads abroad for example the Lancashire and Yorkshire Railway Class 7 in the United Kingdom. Later in the Twentieth century preference moved to 4-6-0 for ten-wheeler locomotives despite the consequent difficulties in achieving an effective firebox design.

• History of the Baldwin Locomotive Works 1831—1920. Philadelphia: Baldwin Locomotive Works. 1920. OCLC 1045993083.
• Llanso, Steve (2021). "Atlantic Coast Line 4-4-2 "Atlantic" Locomotives in the USA". SteamLocomotive.com. Retrieved 17 March 2021.