the.com/rolling stock

means The collective term for all the wheeled vehicles a railway owns and runs — locomotives, carriages, wagons, and the like — as distinct from the fixed infrastructure like tracks and stations.

from A 19th-century railway and business term: 'stock' here means assets or inventory (as in 'stock-in-trade'), and 'rolling' simply distinguishes the moving assets — engines, carriages, wagons — from the fixed ones, like track, signals, and buildings. It entered common use alongside the railway boom, when companies needed a tidy word for 'everything we own that has wheels' on their balance sheets.