Locomotive Type 4-8-2, Babcock & Wilcox
The classification system for steam locomotives was established by F.M. Whyte in 1900, and is used to describe the arrangement of the wheels. Thus, 4-8-2 represents: four leading wheels, eight powered and coupled driving wheels and two trailing wheels. Especially in the steam age, wheel layout was an important attribute of a locomotive because many different types of design were adopted, each wheel was optimised for a different use and often with only a few actually being driven. The leading wheels were used to help the locomotive get around corners and to support the front of the boiler.
This type of locomotive is known as a “Mountain” because it was developed to carry passenger trains over the Allegheny Mountains on the Chesapeake and Ohio Railway. With RENFE it made the Madrid–Irún route.
It was slightly more powerful than the previous ones and the Babcock & Wilcox designers adopted newly designed cylinders, following the proposal of the Kylchap explosion tube by engineer André Chapelon, and it had Belpaire stoves. The prototype circulated only for several years, and its increased efficiency led RENFE to commission 27 more between 1946 and 1947. They were so appreciated by the crews that they called them “Pretty”.
