Planet (locomotive)

Planet is a steam locomotive built in 1830 by Robert Stephenson and Company for the Liverpool and Manchester Railway, the world's first railway built to rely entirely on locomotive haulage for both passengers and freight. Planet introduced a new layout in which the cylinders were placed horizontally beneath the smokebox and drove a crank axle at the front of the locomotive, rather than being mounted on the outside of the frames as on the earlier Rocket. This inside cylinder arrangement proved smoother running and became the template that most British steam locomotive designs followed for decades afterward.