The Jupiter and 119 replicas are just the 2nd and 3rd steam locomotives that I have ever seen, which had working cross-head pumps. In this photo, the cross-head pump is the large, vertically oriented, brass apparatus, located just forward of the drivers. It utilizes the motion of the cross-head to pump water from the locomotive's tender into the boiler. Prior to the invention of steam injectors in 1858, mechanical pumps like this were the only means available for locomotive crews to put water into a boiler that was at operating pressure. Although fairly reliable, the chief draw-back of these pumps was....they would only work when the locomotive was in motion. That meant that the locomotive had to be periodically moved in order to keep the water level up, which wasn't exactly a convenient thing. Although the steam injector solved those problems, it took a few years for them to be accepted, so locomotives built in the 1860s still had cross-head pumps, and some also included one injector. Such is the case on both of these replicas. Each has two operating cross-head pumps, and a single injector on the fireman's side. This enables them to put water in the boiler while sitting at the last spike site for hours....something these engines do every day. As noted above, I know of only one other operating steam engine that has an operating cross-head pump, and that is the Glenbrook, a narrow-gauge, wood-burning 2-6-0, which operates at the Nevada State Railroad Museum. That engine has one cross-head pump and one injector.