1. Weight and eat everything.

    The steam traction likely is only about 80 HO, but the gearing and the wheel size make for incredible torque…Plus the 6 tons or so probably don't hurt….

  2. Did some research on this a few months ago. A lot of steam engines were rated by Nominal Horse Power (NHP) versus actual horsepower. Some large steam locomotives had a NHP of about 20. It was something to do by calculations of the volume of piston and had actually nothing to do with how much power they could produce or load they could pull.

    As well, all traction engines are geared slowly due to the U.K. back in the 1800's regulating top speeds of them and steam carriages effectively handicapping them against foot traffic and horses. This didn't change until I believe before the first world war.

  3. It's not an issue of power. Tractive force is proportional to weight, and the steam tractor is heavier. Note that the modern tractor is not outpulled in terms of power, its wheels keep turning. They just can't get purchase because it's not heavy enough

  4. Peter?

    Less there than meets the eye.

    The steam tractor backs slowly until the Deere's over-cranked tread cleats break up
    the soil under it.

    At that point, the steam tractor has traction and the Deere is just playing DitchWitch.

  5. A coincidence you picked this video, because earlier today RFD had a special on steam tractors, and some of them were bigger than this one.
    It was a very interesting show. I hadn't realized there were steam tractors, and this show had a whole following of people who restore, or recreate steam tractors from long ago.
    Very interesting video.

  6. The angle of the tow strap also gives an advantage to the steam tractor. It provides an uplift force on the modern tractor of T*sin(angle) and the a hold down force of the same magnitude on the steam engine. Say T is 10000 pounds and the angle is 15 degrees, the magnitude of the force is ~2600 pounds. The modern tractors traction is reduced while it is increased on the steam tractor.

  7. In the US, the Early Day Gas Engine and Tractor Association has several chapters devoted to the above, and frequently there are steam tractors and engines at the shows.

    In my section of Oregon, EDGE&TA does two shows a year; one near Klamath Falls over Memorial Day, and another at Hildebrand (NE of K-Falls) over Labor Day. In addition, Collier state park (about 30 miles north of Klamath Falls on US 97) has a live steam and historical show on Father's Day. They have a 25 HP Russell portable engine running a shingle saw, a 10HP Westinghouse tractor, and a 75HP steam tractor (Hart-Parr, if memory serves). I worked with these a bit a few years back, and they're fun machines, although a right pain to set up and shut down.

    Collier also has a selection of more modern machines, including early diesel crawlers and a log slabbing mill. The Corliss steam engine in the shed won't run at Collier; it needed the output of a large lumber operation and several boilers to give it enough steam to run;

  8. I worked for Chicago and Northwestern railroad from 1974-1984. By then they had fully switched to diesel electric engines, but a lot of the old timers still waxed nostalgic over the old steam engines.
    I was told by those who went through the switch that the main impetus was reliability. On any given run the steam engine had a confidence of completing the haul of something like 85 percent. With diesel electric more like 98 percent. And of course with the diesel engine you eliminated the stoker position, that at a time when labor cost was becoming an increasingly significant factor in most industrial operations.
    During my tenure we were rapidly converting from the old friction bearing wheel trucks to the new roller bearings which once done eliminated the carman oiler position as well. Last I knew they were down to a crew of two, engineer and carman brakeman, but that itself may have changed as well.

  9. As the Oulde Cockney Gent would sometimes have it: "'E ken run, but 'e cawn't rilly 'ide!…" – Nicely done…

  10. I've had some limited experience with these beasts. They're quite a handful to operate. Hot work too. They can really dig down and pull especially with a skilled operator. We pulled some ridiculously large plowing contraption through the field once and the engine hardly felt it. Interestingly it was explained to me that many if not most of those old steam engines weren't even operating at peak pressures and performance. They're ancient machines after all and out of an abundance of caution they were very conservative with steam pressures. Even during plowing and threshing demonstrations they were at a fraction of full power. Boiler explosions are pretty horrific and it's only gonna take one for the government to come in and regulate the things into static museum pieces. That's what I was told anyway.

  11. Oddly enough, I was watching a video of snow removal on the Donner Pass railroad lines in the Sierra's last night, and they mentioned that one of the units had had a boiler failure and was being returned to the Roseville, CA yard for repair.

    Those rotary snow plows are steam powered, still!

    When you look at them, they have the single large vent in the roof that you would expect to see for a large engine, but no raised stack. Very tall unit, so no height clearance for a stack, as they barely clear the tunnels and associated track-spanning frameworks. They are moved with a couple of regular locomotives sandwiched between the two plow units situated at either end. This enables them to move snow either direction, without needing to reach a roundabout, and break up the system to fit it on a table.

    Some info on a recent rebuild of these rotary snowplows:

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