How many hp for a horse?

Assuming that this is the typical sled sort of pull, I'd guess the coefficient of friction between sled and ground might be .5. In that case, the horses would exerting a force of 1600 lb. But even so, that is an impressive amount of horsepower out of these critters!

That's the actual pull weight (or drawbar pull for a tractor). The setup is a little complicated, but they use what amounts to a lifting pull over a pulley. The whole machine is mounted on a truck which is then skidded, but that acts only as a friction snub. At some larger fairs, the machine trials may be calibrated on a dynamometer.

Wow. From now on, I am going to eat only oats and hay.

Hp is for lifting - question how many hp for this honkey?

Great photo! Clearly, the driver needs to study a bit of physics...

Hello TVP45

Remember that an ox (bullock) {Not Sandra, I hasten to add} can pull much more mass against friction than a horse.

Kind Regards....

Sparky,

I know oxen can pull much more weight, but I'm not sure about their horsepower, due to the speed isue. I think they're basically big draught horses with a super low gear. I'm unaware of any oxen pulling contests (or even trials). Both oxen and horses were used for pioneers going west in the US in the last half of the nineteenth century and both seemed to do an OK job.

However, there is one job that I know is better suited for oxen:

Wow!!! Now, where the hell did you get this picture from? Looks good.

the only thing i can think off is 1 horsepower = 0.745699872 kilowatts

I saw 2 mules pull a truck out of a creek that a big wrecker could not move.

The mules were a match pair of reds 6 years old.

My guess is a horsepower is closer to what a horse could deliver continuously.

Great post.

I have a book. "Computing Mechanisms and Linkages" from 1948 (Part of the MIT Radiation Laboratory Series of texts prepared under the supervision of the National Defense Research Committee) That describes mechanical computers, although none quite as complex as the Dobbie McInnes.

In comparison, the way we do much of this stuff today seems impossibly crude, in a way: we just gather zillions of discrete bits of data, and repeat (often a fairly simple) calculations over and over and over.

I loved this answer. It took me back to the good old days when Mother Nature worked in analog.

One large horse lifting 16 tons 1 foot in 1 minute = just ONE HORSEPOWER

I have NOT researched the original methods used by Watt, but I would presume the original horsepower would have been with the horse working continuously for hours at a time, not for a few seconds. Virtually all machines, living or mechanical, can produce a peak power vastly in excess of the average over long term.

You didn't specify what kind of surface the horses or the load were working on. If they are steel-shod horses on dirt, then they don't depend only on friction, but actually dig in, making possible considerable non-friction forces. If they were rubber-shod, say on asphalt, the same is true, due to conformation of the rubber to the irregularities of the asphalt.

Yes, quite so. Watt estimated the continuous power, and got it a little wrong. Ordinary horses can't do a hp for long periods, more like 3/4

Watt didn't get it wrong.

He wasn't using ordinary horses. His competition was draft horses, which are a lot stronger. A draft horse can do a little more than 1 hp continuously.

He made his 1 hp engine look good, instead of calling it what it was by underestimating the work a horse can do then saying his engine could do the same.

For some reason, I always thought he had added a "fudge factor" of 50%. Thanks for the info.

I don't think that anyone knows for sure how James Watt came up with the horse power.

It is believed however, that he deduced the term from watching pit(mine) ponies at work and possibly arrived at a figure of a pit pony lifting a mass of 550lbs at a rate of 1foot/second.............which of course gives us the figure of 33000ftlbs/min

This seems to me to be fairly logical explanation.

Hello MOBI

That is exactly the explanation I received, some 50 years ago, when studying Mechanics.

That was before all this new-fangled metrication.

We had good old measure, easy to understand in those days.

Inches, feet, yards, links, fathoms, furlongs, miles, knots, etc.

Pints, quarts, gills, pecks, gallons, kegs, barrels, hogsheads, etc.

Ounces, pounds, quarters, hundredweight, tons, etc.

lbs/inch² - none of the bars, etc.

lbs/feet of turning moment, etc.

Farthings, halfpennies, pennies, threepences, sixpences, shillings, florins, half-crowns, Notes were ten-shilling, One Pound, Five Pounds, Ten Pounds.

Most of the Imperial Measures" as they were called, related directly to known dimensions, and thus were logical, in spite of conversion complications.

A man could be 6ft 2 inches tall, and people would know what height he was.

Confusion set in, once the US decided to have different liquid measure, and their gallons, barrels were smaller than the Imperial.

The "metrication rot" then really set in, with Napoleon's system eventually conquering the traditional Imperial Measure system.

Now, although I have been working with metrics for over 40 years, I tend to think of timber as 2 x 4 (inches) rather than 100 x 450 (mm) and the like.

I have found it is far easier to measure linearly to 1mm or part thereof, rather than the Imperial 1/16, 1/32, 1/64 inch.

Complexity has resulted in the Screw threads, we had Imperial: brass, cycle, BA, Acme, Whitworth, BSF etc.

Then we went, for some obscure reason to UNC and UNF.

That got phased out for the Metric System for bolt/nut threads.

Now we have machinery up to 100+ years old, and the screw thread problem surfaces every now and then, often a special bolt and/or nut has to be made (On old equipment, because Metric machines cannot make Imperial screw threads very well).

OK, now I'm off to eat my (Good Scots food)

Kind Regards....

Too true Sparky............when I came out of the RAN, one of my first jobs (apart from teaching) was the metrication of all books, handouts etc for the students. Once I got into it ,it wasn't too bad..........and at least I had a good working knowledge of the metric system.

My biggest hassle is the units for pressure and stress.......the Pascal (Pa)

The force applied by 1 newton over an area of 1m².............this is the preferred unit and it is such a piddling little pressure............. but........... more commonly used the kilopascal (kPa or kN/m² or N/cm²)

also the megapascal (MPa, or MN/m² or N/mm²), the Bar may also be used. oh! and I nearly forgot the hectopascal (hPa) used for isobars and atmospheric pressure.

Some manufacturers of pressure gauges use units such as kg/cm² however technically speaking the kilogram is not a force, it is a mass. To get kg as a force it must be multiplied by g(force of gravity = 9,81m/sec²), this then gives you your force in Newtons

This adds up when we know that a force of 1N equals the the force required to move a mass of 1kg at an acceleration of 1m/sec² !!!!!!!!!!

Oops. I didn't respond to the second half of your comment.

Most authorities treat friction as a collection of forces rather than a single one (i.e., surface adhesion, asperities, etc). In that vein, "digging in" is considered a frictional force. Rabinowicz, for example, would even count the resistance to broaching as a frictional force (at least in part).

"quarter h/p pony, ie 450lb as against 2000lb + for big shire, pulling 2000lb generator round streets of Birmingham. No need for shoes, steel or rubber. The assistants were there to work the brakes as a pony can pull an awful lot more than it can stop.

The horsepower was invented as a measurement to sell the virtues of machines over horses and the amount a horse can pull consistently for a full working day isn't that great. What they can shift in variable conditions is far more significant as the reserves of power for the difficult sections of a track are massive.

They evolved to travel long distances at low speeds with occasional bursts of escape velocity. If you want a steady consistent power output they aren't at their best, but then you wouldn't use a rocket either.

For local deliveries where carbon neutral is important, or for manoeverability, or working on soft ground or variable conditions pony and horsepower is unbeatable. And for fun, can you have this much fun with any other quarter horse power system?

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That seems to confirm my suspicion that smaller horses can do more work per pound than larger ones.

Hello TVP45

General Rule: The larger the organism, the more inefficient it is.

Kind Regards....