[Andy Carson]

Oh, I am probably not going to be able to resist testing this. I have seen black hooves sold as chew toys for dogs, I can probably find a white one somewhere. Then I just need a high intensity UV light and a hoof rasp to test resistance to abrasion. Check, check. Seems like it would be a pretty easy test, although I would be using shorter duration high intensity light rather than letting the hooves sit outside for god knows how long. Plus, it’s not that sunny here very often. If the hypothesis really is true, the color of the hooves are probably less important in places where it’s not that sunny. More to come.

[Andy Carson]

I am not aware of any scientific studies of hoof color/strength either, but it seems to match with my experience with the few horses I have had. I can hypothesize a mechanism. Keratin is the major structural protein of hoof walls (and hair and horns and other “stuff”). It is made up of many amino acids, and one of the most important amino acids in keratin is cysteine. This amino acid can form chemical bonds between protein molecules (called disulfide bonds) and is essentially the “glue” that keeps a hoof together. Cysteine is damaged by exposure to UV light, which would weaken the hoof. Melanin is very efficient at blocking and absorbing UV light, some might even go so far as to say this is melanin’s evolutionary fuction… People who’s hair gets dry and brittle when it’s exposed to light in the summer are experiencing this effect, and I think animals that spend most of thier lives outside would experience it too. A hypothesis is made to be tested, but I think this makes sense…

[Andy Carson]

This is becoming very interesting… I believe both a deep yoke on a tilt and a two chain attachment on a shallow yoke would act as an evener. If one used two chains, it would be critical that the chains be kept short, moving the pivot point back only a few inches. This still allows the yolk to act as a class II lever, as it rotates around the union of the two chains. If the chains are very long (and or spread wide apart) the lever action would be lost, which I would suspect would be a very bad thing (as Tim points out).

There are another two points in this thread I find interesting. One is if an evener effect is even desirable for oxen. Perhaps as some yokes would have an evener effect and some do not, maybe this is not an important design element. Why this might be is very interesting. Perhaps oxen “lever” a load (with one ox moving and the other acting as a pivot) more than horses do. If this is the case, than a yolk with need to not shift too much weight onto the forward animal and a “lagging” pivot point would be a bad thing and one would want to keep it even. I do not know about oxen enough to know if this is an important aspect to thier pulling…

The other thing that I think it interesting is the general idea that things that have been around for a while must be perfected by now. I do think there is some merit to this idea, but I generally disagree. I think alot of old technology was developed in large part by trial and error and observation. I think this type of design is critical for getting a design generally right and for figuring out what the most important elements of a design are, but I do not have much faith that this type of design truly makes something “perfect.” I believe there is still substantial room for little tweeks to existing technology that optimizes it. Granted, these are likely going to be minor modifications and improve efficiency by less than 10%, but I think they are important none-the-less. I think being open to these types of design tweaks keeps the “language” of animal power “alive,” is exciting and attactive to creative people, and helps animal power adapt to a constantly changing world. I suppose I am getting a bit philosophical here, but I look at the tools and techniques passed down through the ages as a wonderful and very well informed start, not a finished product. I mean no disrespect with this… Indeed, I think some of the old timers might be proud that someone is thinking and tweaking as they probably did to some degree in thier youth.

[Andy Carson]

I was on my riding lawnmower the other day and yelled “whoa” to stop. I think that’s more dumb…

[Andy Carson]

I bet that would work too, Tom. Based on the horse evener analysis, you probably wouldn’t want the ring to hang back too far, maybe in the range of 4 inches or so.

[Andy Carson]

Looking at a yoke sitting vertically, the staple (and pivot point for the ring) looks to be ahead of the point where the oxen make contact with the yoke. If the yoke stayed verticle, than this arrangement would distribute less weight to the leading ox, rewarding them for stepping up. I know the yoke doesn’t stay completely verticle, though, and the angle it assumes under load would have a big effect on this load distribution. If the yoke tilts forward, than the pivot point of the ring might indeed be brought behind the contact point of the oxen on the yoke, and distrubute a greater load on the forward oxen. This ability of the yoke to do this would depend alot on the height of the yoke and the angle it assumes under a given load, as well as attachment point of the staple and the geometry of the staple/ring attachment.

If you have a photo of the particular yoke you are interested in, and a photo of it being used under at least a moderate load (side view), I could speculate in a more detailed way.

[Andy Carson]

I think a picture and flowchart helps to explain what I’m talking about here. The horse and wagon can leave at the top and bottom of the slope. There is no hitching or unhitching needed except for attaching and detaching the counterweight line.

There will always be somewhat of an inbalance in this system, which will require power input from the horses and braking from the wagon. If one is clever about the counterweight, though, all the power from the horses would be exerted pulling downhill where they are super strong, and all the braking would be applied going uphill to feather to descent of the counterweight. The horses just have to walk themselves up the hill and stear. As horses can walk themselves (and only themselves) up some very steep slopes this kind of system might open up some very steep slopes (and what is beyond them) to horse logging.

[Andy Carson]

Carl, you and I are figuring slope the same way. Maybe 60-70% does seem impressive to you, but I think it is quite a feat and it seems very demanding. Scott, this snub line is pretty close to what I’m proposing, except with a counterweight (perhaps a large loag or group of logs) attached to the other end of the line so that it raises as the horses fall. This live counterweight reduces the amount of downward force and if properly chosen could move it into a range that the horses (and some supplemental braking on the wagon) could control. On the return trip, the counterweight would fall and assist in pulling the horses and wagon up. If the counterweight is picked well, if could provide enough brake and power assist to allow the horses to supply a large percentage of the work, with no snub man needed to control braking. You just tie of the line at the bottom and tie off the line at the top. You would want to make sure the line doesn’t break, that would be terrible. Of course, if your brakes on a wagon went out going down a hill like that you’d likely be toast too. I am not sure which I would prefer… I suppose if you have brakes on the wagon and a line then both would have to break… It would probably be better if the path the counterweight takes is different than the path the horses/wagon takes, that way, there wouldn’t be logs falling on you if the line broke.

[Andy Carson]

Scott, I am glad that these slopes were well out of the range of most existing ground harvesting systems, as they definately (at least according to math) seem very very difficult. Earlier in this thread Carl mentioned on this particular job he had a 60-70 percent slope on the return trip for about 50 feet. In the woods around here (and probably in many places in the east), having some sort of techinique to tackle very steep but moderately short slopes like these would be useful. In alot of areas around here, “flatter” areas are excessable if one can get up and down a short steep slope. Using a counterweight on a sky-line (of sorts), I am essentially proposing a low-tech, low-cost hybrid between a cable logging system that is great for steep slopes and the horse drawn system, which is nice for flatter terraign. Both could be made to be low impact. I know the system doesn’t already exist, I am kinda thinking outside the box and doing a certain degree brainstorming. I do think the concept has merit though.

[Andy Carson]

I am still thinking about the challenge of going up and down slopes in excess of 50%. I kinda worry about loss of traction and spinning wheels at these slopes too (with power assist or even with tractors). I really like the idea of using a line or rope anchored on the uphill side to provide positive traction that can’t slip. Bungees can store energy from a descending load and assist in climbing it again, but the amount of tubing needed to store that much energy is enormous and cost prohibitive. I am most attracted to the concept of a counterweight. If one attached a load of two tons (perhaps some logs from a first load) to a tree at the top of the hill through a block and tackle (1:4 ratio), it would provide 1000 lbs of braking force on a steep downhill (this raises the logs) and 1000 lbs power assist going up the hill (the logs descend). Rigging the logs for 20 ft of verticle movement would allow for 80 feet of brake and power assisted movement up and down a steep slope. If the slope was longer, one would have to rig the block up rig up the block higher to allow for more movement. If the slope was steeper or the load heavier, one might want to use a heavier counterweight. 4 tons at a 1:4 ratio, would provide 2000 lbs brake and power assist, for example. 2 tons at a 1:2 ratio would provide 500 lbs brake and power assist over 160 ft for a longer pull. You might even be able to find a tree that would allow for longer verticle movement, and you might not even need the block and tackle… The concept would take time to rig things up, but it’s super cheap, low tech, and gives both brake and power assist on what would have otherwise been wasted power. It also adds zero weight to the fowarder. Perhaps this is already used, I seem to be on a tear of coming up with already invented ideas. 🙂

Even better, you could rig up a cable to run between an anchor tree at the top of the steep slope and another tree at the bottom of the steep slope and hang a log on it zip-line style. Attached through a pulley to your wagon and the top (or bottom) of the slope, this would give you pull and brake assist that is the same weight as the suspended log and would be exactly the same length as the total pull. No need to use an extra heavy weight and mechanical advantage to gain length.

More brainstorming from a bonafide nonexpert… Again, it’s fun to think about this stuff.

[Andy Carson]

If it weren’t for the presense of a 70% slope, I would guess simply adding more horses would be better too. You all would know better than I, but this really looks like a tough task even for a group of 4 (at least from the math). If it’s truly a tough task, than there really isn’t any problem to be solved in the first place. If it is, then that’s another story… Perhaps electrical power is not the way to go and other energy storage methods would be better… In the spirit of brainstorming simpler approaches that don’t use machines, how about this?

Attach a long bungee cord (probably a set of bungees cords) to the wagon when descending a steep hill. When you get to the bottom, stop and tie them off to something (presumably a tree). This stores the huge amount of potential energy that is usually lost when descending a hill. On you way back up, hook up the bungee cords and they’ll assist in pulling you back up the hill. Unhook at the top and there you go. No complicated noisy machines, no potential of spinning wheels, sure traction, sure braking assist without the potential of sliding wheels, and power that is always matched to the application. There would need to be details worked out such as how many bungees to use, how to attach and detach them, how long the cords would need to be, etc. This would probably have the greatest application where most of the slopes are in the range of something that the horses could handle themselves and this “assist” would only be needed on a few steep slopes.

[Andy Carson]

Ha! Those Scandanavians already have a power assist, huh? No sense reinventing the wheel then… So much of that European logging equipment looks so cleverly designed.

[Andy Carson]

Tristan, I am not sure about the moisture aspect, but I would probably want to provide some protection for it. That said, there’s plenty of engines on tractots ans such that have minimal protection from the elements and the starter is right there… as far as it being a winch, I bet it would be great with proper gearing.

You might right Ronnie, about the simplicity of having a big team. It’s not a “slam dunk” for the types of slopes Carl is talking about. Let’s say you have a 20% slope, that would be a draft of 450 lbs for just the wagon (assuming a 1500 lb wagon, 20% slope, 10% rolling resistance) or a draft of 1800 lb loaded to 3 tons total (6000lb, 20% slope, 10% rolling resistance). The horses have to pull themselves up the hill too, adding 600 lb of work for a team (1500 lbs 8 2 horses, 20% slope, no “rolling resistance”) and 1200 lbs to four up. That’s a total of 1050 lbs of load for a team, or 35% of thier weight (1050/3000) for the empty wagon. With 4 horses, that’s 1650 lbs or 27% of their weight (1650/6000) for an empty wagon. Not a big difference here, because the work is predominantly the horses lifting thier own body weight. If the wagon is loaded, that’s 2400 lbs for a team (1800 for wagon + 600 for horses), or 80% (2400/3000) of their weight. For a group of four, that’s 3000 lbs (1800 + 1200), or 50% (3000/6000) of thier weight. So it almost doubled the power on a 20% slope with a heavy load.

At a 70% slope the picture is different. The wagon draft would be 1200 lbs empty and 4800 lbs loaded. A team adds another 2100 lbs of load (3000*70%) for a total of 3300 lbs (1200+2100) unloaded (this is 110% of the horses weight) and 6900 lbs of load (4800+2100) if the wagon is loaded (this is 230% of the horses weight). Four up adds 4200 lbs of workload (6000*70%) for a total of 5400 lbs (4200+1200) (90% of the horses weight) with the sled unloaded or 9000 lbs (4800+4200) (150% of thier body weight) with the wagon loaded. I am sure the horses would appreciate a reduction of 110% to 90% or their body weight in load (as well as a reduction from 230% to 150%) but the additive effect is not as dramatic with these really steep slopes because most of the horses energy is spent lifting themselves. In the end, it looks like adding more horses is most effective when you have mild to medium slopes and a heavy load. A power assist might solve this problem, but implementation might be hard and possibly have little advantage over a tractor. I am kinda brainstorming and seeing what makes sense with the math. 4 up seems to work with the math as long as you don’t have to deal with very steep slopes in the range of 70%, where the power erquirements are so high and the horses spend so much energy lifting themselves.

[Andy Carson]

I am curious about the possiblity of an electrical power assist for hill climbing. The power is there to do this work on paper. 4 deep cycle batteries fully charged will give you the power to climb about 100 verticle feet (50% discharge and 50% efficiency) with a 3 tons load (wagon and logs). Of course, more woud be possible with some power from the horses. I think this could be useful as a “hill assist” for the horses, providing maybe 75% of the power needed to climb the hill. The challenge is more about getting the power out of the batteries fast enough to keep up with a horses minimum walking pace. A V8 starter motor is close to the range one would need to use the power in the proper amount of time (with existing/recycled technology). As a rough estimate, one starter could provide 75% of the power to climb an 18% hill with a 3 ton load, two starters would give you 75% of the power to climb a 36% hill, 3 starters to give you 75% of the power to climb a 55% hill, and four starters would be needed to climb a 73% hill. They would only run for about a minute a pop (or so). They could, of course, run longer with more batteries, but I thought 100 feet of climb was a good target. This system would require some sort of “slushy” linkage between the drive motor(s) and the driven axles so as to still allow the horses to pull some of teh weight and direct the load. Also, there would need to be a charger, but this could run for a long time to recharge the batteries and need not be a big expensive unit. You would probably want one if you were going to use an electric winch anyway… Maybe this gas-electric-animal super hybrid sounds crazy (maybe it is), but electrical assist for hill climbing is established technology for bike riding. Maybe it can find a home here as well? Good brakes would be crucial as well. I would hate to run out of “juice” half way up a 70% grade with a 3 ton load…

PS. This amount of power works in reverse too… In other words, the load coming down 300 feet would be enough to charge about a dozen deep cycle batteries (even taking into account the inefficiency of power generation). If you add the weight of the horses, it might be closer to 20 batteries. Considering the weight of the batteries, it’s really too much power to store unless you get into some advanced technology. This is truly an immense amount of power (esp from animals) and considering that it’s all lost and wasted is a shame… You could generate power from this for sure.

PSS. After a little more thought, it might be a better plan to have jsut one starter and link it to the differentiation thought a long winding torsion spring (like a clock spring). With the horse assist, this will probably provide enough power for hills up to maybe 25%. Beyond that, one would have to let the motor “wind up” the spring, go forward at horse speed, stop (with brakes), let the spring wind again, then proceed over and over again. The spring not only lets the horses take as much of the load as they can, but also distributes the time that the power is appllied over (but providing intervals). This lets things proceed at “horse speed” without having to have a ridiculous number of motors or batteries. You might be able to cut the batteries down to two with this if you keep the generator running. The downside is I haven’t seen a spring like this large enough for what I’m talking about.

[Andy Carson]

Wow, you weren’t kidding about the slopes. I had originally been thinking about some sort of regenerative brakes system, but the amount of energy lost in that amount of weight falling 350 feet is beyond massive. Storing it would take expensive, complex, and/or heavy technology. A smaller amount of energy could be stored in batteries from a generator that might also run a wire winch. If properly geared through a differential, this could provide a super low (and very slow) granny gear for steep and short hills. The math supports a strategy like this, when some extra powered is stored for assist on very steep hills. Implementing the concept might take alot of futzing around though, and really would still probably be inferior to a tractor in the end (except in terms of gas consumption). Another approach might be to use a four up team. Having four might let you use smaller horse that have better power to weight ratios and better surface area to weight ratios allowing them to climb better and cool faster. I think this is my favorite idea.

Maybe not really that creative in end… I was pretty suprized at how challanging those kinds of hills make this. I had somehow been expecting 10% grades, with a few short 25% slopes here and there. That’s an easier problem…i

[Author]

Posts