It doesn't take much to pull a few cars on the flat. A friend of mine Alex Schneider of Loveland, Colorado and I built a 6 inch to the foot scale 18 inch gauge 2-6-2 live steam prairie locomotive. We had Ralph over for our first steam up. That prairie was able to drag Alex's 1 ton Ford truck with a Lincoln welder in the back across the ground with all the wheels locked up. At the first place we had it set up in Drake, Colorado we had a half mile loop of track with a good length of 8% grade. We were able to pull 4 loaded cars up that grade. The prairie was properly equalized, superheated, and with over 3 tons on the drivers developed an actually measured 1700 pounds of tractive effort at 20 MPH.