Does one horsepower really = the power of one horse?

Factual Questions
21

That is very interesting and seems to be accurate. They did the same thing for locomotives except the used a special car filled with weight. From Wikipedia :

dbhp

Drawbar horsepower is the power a railroad locomotive has available to haul a train. This is a measured figure rather than a calculated one. A special railroad car called a dynamometer car coupled behind the locomotive keeps a continuous record of the drawbar pull exerted, and the speed. From these, the power generated can be calculated. To determine the maximum power available, a controllable load is required; this is normally a second locomotive with its brakes applied, in addition to a static load.

22

I think there’s some confusion as to exactly what the concept of “horsepower” is, how it’s measured, and how that relates to tractor pull competitions.

First of all, minor point: just because you’re pulling a weight of 60,000 pounds doesn’t mean you’re exerting a force of 60,000 pounds. After all, I can easily push my 3000 pound car (in neutral), but I can’t bench press 3000 pounds. Of course, my car’s on wheels, so that’s an extreme example, but the point remains: in general, coefficients of friction are less than one, so in general, it takes less than 60,000 pounds of force to horizontally push a 60,000 pound object. [Caveat: I have no idea what the effective COF of a tractor pull sledge in sand would be. I would be surprised if it’s greater than, or even near, one, but that’s not impossible.] Anyway, that’s a minor point.

A bigger point is that there seems to be some misperception that “power” is equivalent to "output force, or “load-hauling capacity.” Not so. A 14,000 HP tractor can pull 60,000 pounds? Big deal. I can pull 60,000 pounds. Just give me a winch with enough advantage, and I’ll make it move. It just won’t move very fast.

And that’s the key with power. Power is the measure of the force exerted, over a certain distance, in a certain time. All three components are important.

23

For reference, I recall top human bicycle racers can generate up to 1500 W in short bursts. Wikipedia says 2000 W. That’s well over 2 hp. So I think the disparity in the definitions, as others have hinted at, is in surplus power after moving ones self, or the engine and trappings in the case of machines.

24

Even more importantly, the difference between average and peak power. According to Wikipedia, horses have a peak power of around 15 hp, but that an average of 1 hp was itself optimistic.

Undead horses have a smaller peak power due to their rotting ligaments, but can average well over 750 watts, having no need for food or even sleep.

25

Yes, and the Continent used a German horse in Stuttgart that is the basis for the metric horsepower.

26

Pretty sure Watt’s horse was a Clydesdale, one of the strongest breeds there is. Therefore most horses can’t even produce one horsepower.

27

Friction will do you in, but I used to build pallet trucks that were rated at 4500 lb loads. For a personal challenge (I worked alone in the warehouse and things got dull) I loaded one up to capacity and gave it a tug. It moved well, but when I pulled it over a joint in the concrete floor one of the standard issue nylon wheels shattered. We had steel wheels for folks who did that every day and those trucks were rated up to 7000 lbs, but pulling that looked like a way to get a hernia. So, it took them 14,000 hp to pull 60,000 lbs? I’m not impressed, and I was never a muscle man.

28

This an old thread but I flattered that someone chose to add additional info after many years. The key with tractor pull competitions is that the competitors are essentially pushing or pulling ever-increasing piles of dirt to make it difficult to get to the finish line like a snow-plow but with raw earth. Of course, it is going to get really heavy towards the end but I think I could move much higher loads with 14,000 well-trained real horses chained together somehow than I could with a single super-vehicle with the same rated horsepower.

I don’t know how you could even get 14,000 actual horses let alone get them to coordinate a pull together but I am guessing they could bring down a skyscraper if they tried hard enough. You don’t have to go that extreme though. Many cars and SUV’s have over two hundred horsepower these days. I will bet that two hundred horses working in coordination can produce a whole lot more power than an engine rated the same at least in the very short term.

A tug-of-war is a no brainer because of the weight differential in favor of the horses as long as they are harnessed together correctly but I would be more interested in a pulling contest to power something very briefly like spinning up a very large but slow industrial wheel.

29

I don’t think you understand what a tractor pull involves. It’s not 60k lbs over a frictionless surface. It’s 60k lbs of sled, pulled over a dirt track, and designed so that the weight progressively shifts forward, digging the front even further into the track and increasing the force needed. It’s unlikely you were applying more than several hundred newtons of force; the tractor is likely applying a few hundred thousand newtons (and contenting with the poor traction of a dirt track).

30

How much room would 14 000 actual horses take?

31

This can’t be true.
You could not effectively hook 98 horses together, or even control them if you could. Just the lines (reins) would be unworkable – too long & too heavy for a driver to hold, or to effectively use to signal the horses. How long would it take just to get all those horses to start pulling? They would have to be hooked with chains, not leather tugs, and with chains that long their weight alone would be a major burden.

The largest hitch I have ever heard of used regularly was 20 equines, and they were the more-docile mules, not horses. (Used to haul Borax near Death Valley, CA.)
And horses can’t sustain a maximum effort like this for very long. So the idea of hitching one horse after another is unrealistic – the first ones hitched would have been completely worn out from pulling all those previous times as each additional horse was added. Just won’t work.

Doesn’t matter – the whole idea is utterly unrealistic.

32

Duplicate post removed.

33

I’ve been looking, and I can’t find any information about what a load of hay weighs, or how much weight any team or tractor of any size can pull. But I believe that a team of horses, like my grandfather had, or the farm next door, easily handled a standard load of hay that a 8 to 15 hp tractor couldn’t. Always thought engine horsepowers were an arithmetic calculation that had nothing to do with what a horse could do. And didn’t they change the calculation a few years ago?

34

I heard you the first time. he he he …

Ever watch those timber working horses that are voice controlled?

Ever seen how sled dogs are hitched?

Do you think they started with one horse? Bet they had a good idea of what was going to happen and were within 2 or 3 horses from the get go.

Control lines? I can’t spell reins. Left lines go to the left side of the left horse, #1, then a short line from 1 to 2, a short line from 2 to 3, a short line from 3 to 4 and a long line from the right side of #4, the far right horse and the nerd controls the chariot with just two lines.

6 in a row is easy. Rows behind the leaders, if real work hoses used to harness work don’t need individual control, they will follow the leader or which ever horse, ox, donkey, mule, ( well they can be more of a problem because a lot will fake pull, even some experienced horses will do that ), so a 6 front & 6 deep is very doable.

Don’t let Western movies guide you about heavy work horses, two different things using very different gear & doing a different kind speed of pulling.

My Grandpa had the first steam tractor in North Texas. Grandma was a master team diver, but never learned to drive a car. My Dad was driving a buck rake at 8 - 10 years old.

And 98 draw bar horse power was a big tractor for farm type work 30 - 40 was way more common. Those are so big & heavy, they can drag 2 D-8 Cats backwards like they are not even there.

Go to the steam tractor events in western OK or TX. Some of that old equipment that they actually work real fields with are amazing. Farmers actually save small fields of different things just for those events so they can do actual work like they were designed to do.

35

Couldn’t you use two of these?

36

On steam horsepower:

Horsepower in steam engines was first measured with the formula, 1hp for every 10-14 square feet of boiler surface. But this formula was outdated by the increase of steam pressures in the engines, yet the formula was used until 1911. Then a new measurement-brake horsepower (which was measured on a Prony Brake-type dynamometer). An engine from 1908, which was advertised as 30hp, might be advertised as a 100hp engine in 1912! Some ads had both types of horsepower rating, such as 30-100hp.

And about practical horsepower, it doesn’t matter if a vehicle has 1 million horsepower, it has to reliably apply the power to the work…put the power to the ground. A 40 horsepower tractor, if weighted properly for good traction can outperform a 60 horsepower tractor that’s too light for the job. Just like good tires or bad tires on a car make a world of difference!

37

As I understand it, Watt did the measurements to establish the work rate of a horse, because they were the competition for his engine. Engineers in those days commonly worked out a minimum rate (for a beam for example) and then added 50% for safety. They did not want those structures to fail. That is why so many of those structures are still in use today, even with much higher loads than the original engineer calculated for.

Watt used the same reasoning and added 50% so that a two horse motor would always beat two horses in any trial someone might dream up. Add in the fact that his engines ran all day without needing a rest, and he was on to a winner.

38

Assuming spherical horses…

Actually, cubic horses would pack better.

For ordinary horse-shaped horses, it would take approximately 14,000 times the space occupied by one horse.

39

This works out to 5000-6000lbs per horse. Interestingly enough, this 1hp Winch is rated to pull 6,000lbs.

Probably goes slower than the largest draft horses at a pull competition, but may very well outpull your typical riding horse.