how many horses

[Tim Harrigan]

I think tractor manufacturers are happy with machines that will pull (drawbar) their own weight (mass). 100% efficient. Nebraska tests are done on concrete and they measure pull in all gears, fuel consumption etc. Early tractors also introduced rotary power options, flywheel and pto that eased the transition. The lawn mower is a measure of rotary power and the hp is relatively high because of the high rpm, not particularly high torque.

[Carl Russell]

This is in part becoming a discussion that I have been trying to have with the “Alternative Energy” crowd for several years. Our culture has become so dependent on the internal combustion motor that we just take for granted the advantages that they provide, without really looking at the efficiency of the conversion of fuel into power.

If the HP efficiency is really as low as has been described here, then it must also apply to the fuel efficiency per unit of work. The dependency on motors has motivated initiatives to use Bio-fuels, but the discussion about conservation and energy efficiency when directed toward animal power is still a non-starter.

I wonder if we can get together some detailed info that shows how much more HP animals have in comparison to machines combined with fuel efficiency per unit of force, to show how viable animal power truly is in comparison to machines using bio-fuels.

I would love to have this presented at 2010 NEAPFD. Tim, Ben, anybody else? Would you, could you present some of this at our event in Tunbridge, VT 10/15-17/10?

Carl

[Tim Harrigan]

The hp unit was developed by James Watt in the late 18th century. He wanted to rate his steam engine in terms of the competition, the horse. After some tests he determined that a horse could lift 366 lbs of coal from a mine at a rate of 1 ft/sec or 22000 ft-lb/min. He increased it by 50% to 33000 ft-lb/min (550 ft-lb/sec) to underrate his steam engines. That has been the unit for hp ever since. A watt is now a unit of power. One hp is 756 watts.

[jac]

The bio fuel thing is a real bug bear of mine.. fuel from food bi products or animal waste fine… but fuel from wheat or any other food product is an international scandal.The horse can utilise less than perfect grazing but bio fuel needs to be grown on good arable land. As you say the green loby have upteen chances on tv to push animal power but choose to try and find ways to keep the car/tractor running at seemingly any cost.. How much of the bio fuel does it take to get the end product?? The cultivator pulled by a team of say 7 horses is doing part of the cultivating by simply pulling the implement . The tractor leaves tracks that the cultivator needs to eradicate so extra tines behind the wheels need to be added..more power needed..
So Watt increased the readings purely to make his invention look more efficient beside the horse !!! Looks to me as if thats back firing now.. It might be an idea to try and attack this on two fronts.. the efficiency of animal traction and also the subsidy laden ineficiency of bio fuels.
John

[Traveling Woodsman]

@Carl Russell 15058 wrote:

This is in part becoming a discussion that I have been trying to have with the “Alternative Energy” crowd for several years. Our culture has become so dependent on the internal combustion motor that we just take for granted the advantages that they provide, without really looking at the efficiency of the conversion of fuel into power.

If the HP efficiency is really as low as has been described here, then it must also apply to the fuel efficiency per unit of work. The dependency on motors has motivated initiatives to use Bio-fuels, but the discussion about conservation and energy efficiency when directed toward animal power is still a non-starter.

I wonder if we can get together some detailed info that shows how much more HP animals have in comparison to machines combined with fuel efficiency per unit of force, to show how viable animal power truly is in comparison to machines using bio-fuels.

I would love to have this presented at 2010 NEAPFD. Tim, Ben, anybody else? Would you, could you present some of this at our event in Tunbridge, VT 10/15-17/10?

Carl

This is something that I have always been interested in, in fact I almost did a research paper on it in high school. By this I mean a real world comparison between draft animals and tractors/skidders as prime movers, one that looks at the big picture of, say, a lifetime. In reality, the comparisons would be different depending on what specific piece of equipment you’re talking about, and I am specifically interested in comparisons involving farm work and logging. I may also be interested in research on earthwork too, because when I was talking with the Forest Service in Utah about some large scale dam work, this issue was central to their decision making process. Specifically, what can realistically be accomplished with horses, and all of the other factors involved besides actual production rates that would affect the project. They had wildly ranging estimates on production rates, and were forced make decisions based on the lowest production rates, which resulted in a decision to go with helicoptering excavators into a pristine 500,000 acre wilderness area. This also brings up the point that horses can accomplish a wide range of tasks that many different pieces of equipment have been made to accomplish. For instance, my horses can skid logs, pull any piece of farm machinery, move dirt, be ridden, and pack loads. I was just at a hunting camp where I packed in camp on my team, rode them during the day while hunting, then pulled my truck out of the ditch when we were trying to get over the pass.

There was a fair amount of research done on this in the ’20s and ’30s, when horses were still a major source of power and engineering had advanced to needing hard data, much like what we’re talking about. I would be interested in pursuing this further, such as getting accurate numbers and compiling a list of all the factors involved in using animals and tractors on the ground level, not just theoretically or in artificial environments like a pulling track. Carl’s point about horsemanship is but one consideration that should be included here. Cultural skills are a very important part of this conversation.

And as far as comparing animals to machines on fuel efficiency per unit of force, that is a very interesting idea. You would have to come up with some unit of energy that you could measure both muscles and fuel/engines with. I’m sure somebody somewhere has worked on this idea at some point. I know of several old books that at least deal partly with this. I think I will start looking into it.

On a different note, to apply Tim’s equation for estimating horsepower to some numbers, let’s use some dyno numbers and 3 mph, this being a common working speed for horses. And many forces exerted at a horse pull are actually done faster than a walk. This would definitely be the upper end of anything any team has ever done, but it’s interesting to talk about anyway.

So,
HP = #4000 x 3(mph) / 375 = 32 HP

Or,
#4000 x 2(mph) / 375 = 21.33 HP

Or, to use the biggest numbers,

#4900 x 3(mph) / 375 = 39.2 HP

Or,

#4900 x 2(mph) / 375= 26.13 HP

As you can see, the speed can have a big influence on horsepower numbers, but it is a real world consideration in how much work can actually be done. Interesting to think about.

I wouldn’t rule out making a presentation on some aspect(s) of this if you were interested Carl. I would have to do more research before I would feel comfortable making a presentation. Is anybody aware of research about this stuff? Anybody have thoughts?

[Andy Carson]

This is a fascinating discussion. Because of the second marker on youtube videos, there is no need to guess at the speed of the pull. I got about 8 seconds on really heavy pulls. Most pulls were faster than this, in the heighborhood of 6 seconds… At any rate, 27.5 feet in 8 seconds is about 2.34 MPH. That comes out to 30.6 HP, or 15.3 HP each. It would also be interesting to estimate the HP that a team can put out on average during a days work. If a team is pulling a 12 inch plow at 6 inches deep (as in the previous posts), the draft might be between 600-800 pounds and the pull might be at 2-3 MPH. If so, that would be an output of between 3.2 and 6.4 HP. That’s less than 10% of the maximum output over a few seconds, but much more than 1 HP each.

[Carl Russell]

Traveling Woodsman;15067 wrote:

……..

And as far as comparing animals to machines on fuel efficiency per unit of force, that is a very interesting idea. You would have to come up with some unit of energy that you could measure both muscles and fuel/engines with. I’m sure somebody somewhere has worked on this idea at some point. I know of several old books that at least deal partly with this. I think I will start looking into it.

…….
I wouldn’t rule out making a presentation on some aspect(s) of this if you were interested Carl. I would have to do more research before I would feel comfortable making a presentation. Is anybody aware of research about this stuff? Anybody have thoughts?

I am considering a break down of the different energy centers, if you will, those points in the machine where the energy produced by the motor is reduced. Not so much a comparison of how efficiently horses or tractors utilize the intake fuel, but some comparison that can show the power apportionment.

For example a tractor has to use a certain amount of fuel to run all the attachments, drive the transmission, carry the weight, and perform the work. Because the power range is limited by the engineering, then there is always some portion of the power that is not fully utilized to perform the task. (A similar example is that it take 2 KW to transmit every KW of electricity used in the average home.)

Horses however inefficient they may be in terms of conversion of food into power, they are a flexible power unit, and they can be used to exert a wide range of energy output to more appropriately meet the exact power demands of the task.

These types of facts and figures may not be easy to arrive at, but as our culture begins to evaluate energy sources, one of the primary factors need to be efficient conversion. If we can show that for every calorie of petroleum that is used, that a certain portion is being wasted because of the dependence on the internal combustion motor, then we may be able to engage more people in this thought process. It makes me think of the figure that Michael Pollan used in the Omnivores Dilemma, something like it takes 10 calories of petroleum for every calorie of corn in processed food. How much of this is actually applied effieciently to the process, and how much is burned because of inherent inefficiency? These kinds of comparisons seem to be captivating to people.

I just don’t have the time or resources to do this research, so I am hoping that some others have done something like this. But I would be glad to be involved somehow.

Carl

[near horse]

Where do I start? Lots of ideas and comments to make. In relation to Old Kat’s Kubota vs horses story – therein lies one of the benefits of using animal power you can add HP as needed (or borrow). Not so with the tractor you bought. So the modern solution is overkill – buy the biggest tractor you can afford, even if most of the time you’ll not be using that extra HP.

I am considering a break down of the different energy centers, if you will, those points in the machine where the energy produced by the motor is reduced. Not so much a comparison of how efficiently horses or tractors utilize the intake fuel, but some comparison that can show the power apportionment.

Carl and others – isn’t the Nebraska test number essentially the end product ( like the 1KW in your electricity example)? So are you just wanting to figure out what the input is that is required to generate that end product (the 2KW in your example)? So we could measure the mount of fuel consumed do do the work and calculate how much E is in it. The difference btwn how much E we burned and how much was necessary to do the work should be the amount lost in the ” inefficiencies” of the tractor – wheel slippage, heat, friction …..

Is that what you were thinking?

The fly in the ointment is the “time component”. It takes the same amount of energy (calories) to walk a mile as it does to run a mile. Just takes longer to walk the mile. But we are always get concerned with how much work per hour or day can a tractor or a team do.

I think the alternative E crowd sees the need for new ways of providing E but they’re stuck trying to fit it into the current, massive and entrenched infrastructure already present. I don’t see us getting away from the means of transportation we have in place BUT we can look into other ways of powering those vehicles. And maybe draft power could fit in here – if say folks drove electric powered cars, there still needs to electrical input from somewhere to charge the batteries – if it comes from the grid then you’re really using coal, natural gas or nuclear power. But why couldn’t we use draft power to generate the electricty to charge the batteries? MAybe something like a pulley setup (like winding the bucket up out of a well).

An interesting sidelight for horse afficionados – there was a pretty neat research paper written back in the early 80’s called “Why Horses Change Gait”. As you might expect and they show very nicely with graphs in the paper, within a gait (like walking), as a horse increases energy spent on locomotion it increases speed to a point. At some point it becomes more efficient to switch to another gait. Easier to see in a graph than my explanation.

Sorry about the rambles – couldn’t seem to get my thoughts straight tonight.

[mitchmaine]

the skidder is an amazing tool. you can hook a chocker to a tree and literally rip it, stump and all, from the ground. how many horses does it take to produce that much power? who cares. i think the beauty of the horse is its range of motion. a horse can do things for you that no machine can match. a team of horses twitching wood can squeeze between two trees narrower than their evener and keep going. walk to a tree and spin in one spot heading out. when your machine is stuck, its stuck. a horse is never stuck. i used to hotn yard for a quy with a skidder on a loooong hitch. we were back a mile and a half in the woods across two farms, and three brooks. i’d hot yard for him treelength and have 10 or twelve trees ready headed out. he’d make a hitch an hour and we did ok. i couldn’t have made a living there, and he couldn’t either. both had a job. you can’t compare a horse to a machine. they ain’t the same.

[Tim Harrigan]

The energy density (cal/gal) of diesel fuel can be determined from published values. Fuel consumption of forwarders and other machinery can be estimated based on fuel consumption per engine hp and likely fuel consumption rates can be estimated based on the Nebraska tractor tests. Energy use (cal) of horses can be based on feed intake. Good estimates of harvest productivity (bd-ft/h) will be needed for the horse-drawn system and whatever system it will be compared to. The comparison could be hp/bd-ft or cal/bd-ft delivered or whatever units of measure make sense. Hp output for the horses can be estimated based on reasonable and likely transport speeds and the size of the logs harvested. The calculations are not particularly difficult, a harder part is sizing and defining the nature of the systems to be compared.

[jac]

Comparing horses to tractors on purly work they can achieve is a non starter, but as Mitchmaine said, horses can be more flexible and besides that do much less damage. A skidder does root damage to good trees. I believe that in Scandinavia they use horses to feed a skyline which means they dont need to set up so often and save a lot of time.. For me the argument is the amount of wheat or other food product that is used to make fuel. I did a quick Google search and some of the figures blew me away..1.2 million tons of wheat to make 80m galons of ethanol.. now Uk wheat runs at around 3t/acre so on that basis you need an acre to keep just 4 cars going for a year at 40mpg and 12000 miles/year!!!!. Roughly.. Im not that great at the figure stuff.. Am I wrong to think that its ethicly wrong to keep cars going when half the worlds starving ???
John

[CharlyBonifaz]

Am I wrong to think that its ethicly wrong to keep cars going when half the worlds starving ???

no, because I think the same;
problem is: distribution; in parts of this world there is so much food it is thrown away while in others there is none
I do cringe when I see wheat being burnt for fuel (shows how cheap it has turned); still can hear my parents “don’t play with food”…..

[Carl Russell]

Well I didn’t mean to start a discussion to COMPARE horses and machines. My interest is in pointing out how inefficient machines are at turning fuel energy into energy output. This has been highlighted throughout this discussion in discussing the reduction of HP when applied to work.

Mitch’s point about the skidder winch is a perfect example. You can winch much more with a skidder than you can pull. Winching the load up into the basket gives them the advantage, and traction, they need to pull the load. The winch has more effective power than the wheels do.

The concept that macines are so effective at converting fuel into motive power is at the root of modern assumptions about animal power. I agree that pure comparisons of energy/unit of work are pointless, especially for draft people, but there is an undisclosed INefficiency associated with machines that continues to relegate animal power to the dark ages.

When fuel was cheap and apparently endlessly available, the inefficiency was overlooked for all the EASE that the motor provided. It still provides ease, and PROficiency, but the inefficiency should be more significant, except that most people are so inamored with MOTOR EASE that they don’t want to believe how much fuel/energy they are wasting.

A particular example of how I see this being applicable is the difference between using a tractor with a mower or baler, versus a team with motorized forecart and mower or baler. There is an increased energy efficiency because the horses are moving the load which they are ideally suited for, and the motor is running at it’s designed level of out put, getting the most out of the fuel. We ran into this when we were setting up a demo at NEAPFD. If you read the specs for the round baler, the tractor HP required is much higher than the HP provided by the motor on the forecart.
However the smaller motor is entirely sufficient to perform the task of baling.

Obviously in this case there is still an energy requirement to move the load, and as Geoff pointed out it is the same amount of calories regardless of the motive power. It’s just a matter of where the calories are coming from, and are they renewable, and can that power unit be used for many different applications?

Another point to consider is even though it takes the same energy to travel a distance running or walking, what if you were yelling at the top of you lungs and swinging you arms wildly? There would be alot more energy spent then. This is the type of energy that I see motors using. There is a designed level of fuel use that exceeds the amount that is actually needed to complete the task.

Anyway, 10 below here today, gotta go feed some critters, Carl

[Carl Russell]

I also got thinking about another example. When I was building this house I had a generator with an idle control so that when I wasn’t drawing electricity it would idle, but as soon as I hit the trigger on the saw it would rev up. Even at that it was generating about 65 amps, and the saw was only drawing about 10 amps. This is the way that engines perform a lot of work. Because of the way they burn fuel it is rarely apportioned precisely to the actual power demand.

The solution in the case of the house was to put in my battery bank. Then I could dump amps into the batteries as fast as my generator could make them, then draw them out in accordance to the task at hand. This is another feature of animal power. Their bodies are like batteries is some sense. They are not burning fuel as it is being put in, they are burning reserves, and they are only using as much energy as they need to accomplish the task. They can automatically change gaits and respond to the changing demands of the work.

Another part is that animals are growing, living components of the farm system. They are actually energy sinks, whereas motors are destructive of the energy stored in fuel molecules as it passes through them. They gain nothing from it, and they give nothing back from using it.

I know I’m making this complex, but it is the basis for why I started using draft animals 25 years ago, and have never owned a tractor.

Carl

[Tim Harrigan]

There are many interesting aspects to this. In my way of thinking it is important to decompose the major issues in the fashion of peeling an onion. Inefficiencies exist in both systems. Engine-based systems have many inefficiencies but the productivity is greater. Animal-based systems have certain power delivery advantages but their engine is running 24/7. Certainly they can be integrated in other parts of the system, but this daily care and feeding responsibility was perhaps the biggest wedge that pushed horses out and let tractor power in. So while I really appreciate the energy and power delivery of draft animals I still think it is important to understand how energy use nets out. On an energy per board ft basis a low input system may have an advantage compared to a high input, higher productivity basis.

I am not exactly sure how to sort these things out without comparing two or more systems. It is sort of like the keyline plow question. If such a power intensive operation provides real and measureable benefits then they have to be real and measurable, not just a promise or a nice story. If you plow the entire field and things look better or worse the next year, was it because of the plowing? My pastures look different every year based largely on temperature, rainfall and rainfall distribution. If I split the pasture and plow only part, then I can see, measure and separate the plowing from the other environmental effects that I can not control. So I need to make objective comparisons to draw defensible conclusions. That’s the way I roll.

Now the ethical issues, environmental effects, renewable energy, those are deeper layers of the onion. Integral and important in a assessment of the entire system but different questions in my mind. If that is the way the assessment needs to go, that is fine, but if energy inefficiency or delivery is a component of a system I am trying to understand and you include it in your defense of a challenger system, my first question is ‘How inefficient is it? And compared to what?’

It is almost always harder to identify the specific question you want to answer than it is to actually answer it. In one of the classes I teach I tell the students to set field comparisons up to answer one question at a time. They do that by asking a question that includes the word ‘or’. Keyline plow or no plowing? Fifty lb/acre of compost N or no N? Do not ask ‘keyline plow and 50 lbs/acre compost N or no plowing?’ That question can be answered but it is more complicated and the separate effects still need to be unraveled. If you ask that question and measure or observe real effects you still do not know if the effect was the compost N or the plowing.

[Author]

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