Schematic drawing with dimensions
1922 Locomotive Cyclopedia of American Practice
The USRA standard model for heavy, slow coal trains was the Heavy Santa Fé. ALCO-Brooks delivered 135 and Baldwin 40 more. By far the largest number were the 130 members of the Pennsylvania Railroad's class N2s. The locomotives were generally considered a successful design that fulfilled their tasks satisfactorily. As early as 1923, the PRR rebuilt them with new boilers with Belpaire fireboxes and renamed them class N2sa. A fundamental problem with the Heavy Santa Fé was the very long frame, which was not cast in one piece. This warped over time, leading to increased maintenance costs. 