This is a Marx #21 locomotive that I converted to windup power. It has two Marx Riser Gear motors that have been spliced into one unit. As the video shows, it doesn't have any problem pulling a 15 car train around the layout, even through the O27 curves. It will pull a 15 car train about 90 feet on the mainline - not bad, considering most Marx windup trainsets only had 3 cars.