A locomotive bed is a one-piece steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 casting

Casting

In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...

 for a steam locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 that consists of the locomotive frame

Locomotive frame

A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...

, the cylinder

Cylinder (engine)

A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...

s and valve chests, steam pipe

Steam pipe

Steam pipe may refer to:* The steam pipe of a steam locomotive passes the steam from the boiler to the cylinders.* District heating, a system for distributing heat.** New York City steam system, a district heating system in New York City....

s, and smokebox

Smokebox

A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...

 saddle, all as a single component. It was a development of the final years of steam locomotive design in the United States. Most large cast-steel locomotive beds were made by General Steel Castings

General Steel Castings

The General Steel Castings Corporation was a steel casting corporation in the United States established in 1928by the Baldwin Locomotive Works, American Locomotive Company, and American Steel Foundries....

. The advantages included greater strength and more accurate alignment.