| Atlantic Coast Line 4-4-2 | |||||||||||
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 Atlantic Coast Line 4-4-2 No. 153 | |||||||||||
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Atlantic Coast Line 4-4-2 were express passenger tender locomotives built by Baldwin Locomotive Works (at that time known as Burnham, Williams & Co), initially for the Atlantic Coast Line Railroad as classes I/I-2 and I-3. They were the first design in the world to exploit the larger boiler and firebox possible with a 4-4-2 design compared to the classic 4-4-0 .
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.