Cross section and underside plan view of one of Robert Stephenson's 0-4-0 "Samson"-type steam locomotives from 1831, designed for hauling goods trains. The cross section shows the innards of the boiler, firebox, and smokebox, as well as the steam piping and details of the running gear. The underside plan view shows how the piston rods run underneath the front axle to the rear crank axle.