tender

A tender, in the context of steam locomotives, is a separate vehicle coupled to the locomotive that carries its fuel and water supplies. These supplies could also be carried on the locomotive frame itself, in which case it was called a tank engine. The capacity of a typical European main-line locomotive's tender was around 10 tons of coal and 8,000 gallons of water, with North American locomotives often having higher capacities. The basic features of early successful steam locomotives, like the multitube boiler and a system for exhausting steam to create draft, continued to be used throughout their operational lifespan.1