[mstacy]

Geoff,

There is no catch. But there is no free lunch either. Approximately half the energy content in a stick of firewood is in the volatiles and the other half is in the solid carbon.

Whether you “pyrolize” or burn the wood the end results are not that different. As the wood is heated the volatiles are driven off and the carbon is left behind. Both components will burn provided there is enough oxygen and a high enough temperature to support combustion. You’ve seen this everytime you sat in front of a campfire. The charcoal is what’s left after the volatiles have been driven off.

Howie alluded to the efficiency of gasification stoves … and compared to a conventional wood stove … and the way we use them he’s right. Most wood stoves spew pyrolysis products (unburned fuel) up the stack when we pinch down the air flow to keep the fire going all night. A gasification stove is designed to ensure that the pyrolysis products are fully combusted rather than wasted (adequate secondary air and high enough temp to support combustion).

If you burn the volatiles and keep the charcoal you’ve recovered approximately half the energy content … and kept a big lump of carbon to use however you see fit. You have to decide. Would you rather burn that charcoal (heat your house, water, etc) or keep it? It’s akin to having your cake and eating it too.

Regards,

Matt

[mstacy]

Great question George. I wish I knew the answer. It would be extremely helpful to have basic data on draft requirements for various pieces of equipment (plows, tedders, mowers, etc).

Has anyone seen this sort of data (pounds required to pull various implements)? This ties into the work that Tim Harrigan and Andy have been doing.

With draft animals we’re working with limited power, delivered over a fairly limited speed range. A tractor has extra power to waste and multiple gear ratios to optimize shaft speed relative to ground speed. I think it’s reasonable to assume that we aren’t going to exceed 1hp per animal for extended time durations. I’m talking about real work, not a 6 foot exhibition pull. 1hp = 550 foot*pounds/second. Given that a draft animals gait is basically fixed at something on the order of 5 feet per second that equates to about 110 pounds (in the horizontal direction) per animal.

It’s definitely a challenge to design an implement around those limitations, not impossible but challenging. I suspect that efficiency was not a primary design criteria for tractor implements. When you’ve got 40 plus horse power to work with it really isn’t that critical if you waste a few. Next time you jack your car up, turn a wheel by hand. The amount of bearing and brake drag is significant. Now imagine that same amount of drag on a bicycle. It would kill you.

In general what we need for animal drawn implements are VERY efficient mechanisms, narrow “swaths” (width of plow bottom, tedder width, mower bar length, etc), and light weight construction. This last one (weight) is also critical. A ground driven implement should weigh just enough to get the job done. I’m convinced that my MD9 mower is far heavier than it needs to be to provide enough traction to work. This is an artifact of the cost effective manufacturing methods of the day. Think “light wall tube bicycle construction” versus heavy iron casting.

Regards,

Matt

[mstacy]

Robernson,

I made one from scratch. The old pitman arm had long since rotted away by the time I took possesion of my #9 mower.

I don’t know how long the original factory parts were. I determined a lenth to set the register more my particular mower (knife stroke centered on guards). A drawing is attached.

Regards,

Matt

[mstacy]

Geoff,

I’ve got a couple books on gasification. As you mentioned a lot of work was done on this in Germany during WW2. You should be able to find oodles of information online. Try searching “downdraft gasifier”. http://taylor.ifas.ufl.edu/documents/Handbook_of_Biomass_Downdraft_Gasifier_Engine_Systems.pdf is one document that popped up.

There are up, down and crossdraft systems. Each type behaves differently in terms of efficieny, gas quality, and responsiveness.

Almost any wood stove is working as a gasifier when you pinch down the air inlets. If you see thick white smoke coming out of the chimney that’s a pretty good indication that you’re dumping pyrolysis products (unburned fuel) into the atmosphere. If you plumb that to a burner (or engine), mix with air and provide an ignition source you’re in business.

Regards,

Matt

[mstacy]

On http://www.amsteelblue.com/cpage.cfm?cpid=518 I noticed that they offer a stretchy version too. This ties (pardon the pun) back to a previous thread on draft buffers (Tim Harrigan, Andy, et al).

This stuff might prove vastly superior to chain for hitching draft animals to heavy loads. I’m referring specifically to starting the load rather than trying to get a free lunch out of the buffer. The stretch should allow the animals to utilize their kinetic energy rather than just straight muscle strength to start the load … without hurting themselves. Trying that trick with a chain would be begging for injury to beast and equipment.

Has anybody tried using this sort of tow strap like this? I like to hear about your experiences with it.

Personally I think this is the application where “draft buffers” offer the most benefit.

Regards,

Matt

[mstacy]

Rod,

Is your primary intent to use this as a parking brake or to control speed on long descents? I would be concerned about using a pneumatic tire as the friction medium for the latter.

Ultimately all friction brakes convert kinetic energy to thermal energy.

But if you really just want a parking brake consider mounting the brake pad on a lever oriented such that when the animals pull forward it tends to engage harder. This would be self energizing … i.e. power brakes on the cheap. However that self energizing feature only works in one direction.

Regards,

Matt

[mstacy]

Eric,

I am very interested to hear more about your rice experiments. Have you given any thought to putting a few pigs to work in the flooded paddy field with portable electric fencing? Access to dry ground and or an elevated shelter would probably be very important. I bet that three or four pigs could puddle a small paddy in no time flat. I’ve never heard of this being done … but who knows. I’m amazed at how quickly even one of my Tamworths can tear up the sod in a 30 x 30ft section of pasture to unearth all the glacial gifts. I’d be amazed if they chose to test the fence while standing knee deep in mud.

Years ago I spent three years in northeast Thailand. I was fortunate enough to work with small scale rice farmers. Sticky rice is very popular there. Most of the fields are plowed (extremely light plow) and puddled with a simple spike tooth harrow pulled by a single water buffalo or 10hp hand tractor with montrous paddle wheels. The vast majority of the crop is harvested by hand with grass hooks and bound into bundles with zip ties made from split bamboo strips. Roughly half of the crop is still threshed by hand.

Regards,

Matt

[mstacy]

@Tim Harrigan 17214 wrote:

The pulling forces were measured 5 times per second with a hydraulic pull meter in the towing chain.

Tim,

This answers one of my questions from the “load buffering” thread. Your team is towing a relatively sophisticated data aquisition system. You have a pressure transducer coupled to a hydraulic cylinder, sampling at 5Hz? Very impressive.

Are you recording axial loads, or just the useful forward component thereof? It would be extremely interesting to combine your data with trace angle and ground speed to evaluate power, efficiency and other factors. Fascinating!

Regards,

Matt

[mstacy]

Tim,

This is a great thread you’ve started. How are you measuring draft loads (spring scale, load cell, etc)?

I would love to see draft versus time graphs if you are using some sort of electronic data aquisition. The load buffering you refer suggest that periodic variation in ground speed is the root cause. I had not considered this but it makes perfect sense. You don’t happen to have any ground speed (vs time) data do you?

Load buffering could potentially benefit the team (and the teamster getting more work out of them) by reducing shock loads. Also consider than an elastic tug allows the team to use momentum to start a load without hurting themselves (akin to pulling a stuck car out of the ditch with a nylon strap instead of a steel chain).

Thanks for the insight on wheel compliance too. You make a great point about the importance of substrate hardness as a factor in the overall rolling resistance.

Great work. Keep it up.

Regard,

Matt

[mstacy]

Josh,

There’s a plowing competition at the Billings Farm Museum in Wooddstock this spring (first weekend in May I believe). Oxen run on Saturday and horses on Sunday.

My situation is not that different from yours. I have a team of young steers and an ancient walking that I have no idea how to use.

Regards,

Matt

[mstacy]

There are two types of water buffalo. The “swamp type” is common throughout southeast asia. I raised one for a year when I lived in Thailand. They are primarily used for draft and meat. A single animal pulls a walking plow through flooded rice paddies.

The “river type” is common in parts of europe (italy). Guess what “buffalo mozarella” is made from. There is a water buffalo dairy here in Vermont (http://www.bufaladivermont.com/). I visited this farm a few years ago. I was hoping to find a pair of swamp type calves to train as oxen. No luck. However these animals seem suprisingly well adapted to our temperate New England climate. I can assure you that they don’t swim/wallow every day.

There are a handfull of water buffalo farms in the US (Florida, Arkansas, Texas, Vermont, …). I have not been able to locate anyone raising swamp type animals though.

Regards,

Matt

[mstacy]

1 horse power = 550 ft * lbf / second = 746 watts

No single equine or bovine is going to put out significantly more than 1hp for any significant duration of time. Any multi animal hitch or mechanism (e.g. sweep) knocks that figure down even further due to mechanical inefficiency.

Furthermore I’ll wager that the origins of the unit of measure (“horse power”) can be traced back to it’s namesake.

Regards,

-Matt

[mstacy]

Josh,

You’ll find a wealth of advice on this site from the experts. But I’m not one of them. However, in the context of your question my lack of experience may be a virtue. I was standing in your shoes last October, as the proud owner of a devon heifer and bull (both 3 months old).

The first step is to start building a relationship with each animal individually. Don’t be in a big hurry. Work them one at a time. Touch and handle them A LOT. For safety I think it is extremely important. If they don’t get used to you working behind them you’re going to get kicked at some point. A brush and feed can sweeten the deal.

For me the next step was leading them on a halter. I’d say “walk”, tap them on the rump with a whispy stick, walk a short distance, say “whoa” and give them a light tap on the nose. I’m convinced that the actual words don’t matter at all. You could say “banana split” and “martini” as long as you’re consistent. The halter is important, especially initially, but focus on getting them to respond to stick and voice. When they’re stopping and starting well add gee and haw into the routine, again using the stick to reinforce the signal (very lightly).

Keep the training sessions brief and frequent. I’d work mine for 15 minutes or so before and after work every day. We built up to long walks in the woods and on logging roads. Walk them over small logs, through and around obstacles. The more things you can familiarize them with the better in my opion. I have to cross a bridge to get to my woodlot. So we spent a lot of time on that. New situations can be scary for them. Coax them on but don’t push too far too fast. Take baby steps. Challenge them but be careful to setup situations where they can succeed. When you push too far or too fast it will definitely knock your training back a few steps. You’re trying to build their confidence in you as much as anything else.

Have fun an keep us posted on how you’re doing with them.

Regards,

-Matt
W. Topsham, VT

[mstacy]

Tim,

I’m just looking for a little extra traction on packed snow / ice this winter. I use my little guys to skid firewood, haul manure on a sled and stuff like that. We experimented with plowing the driveway too. I want to rig up a better plow this year.

-Matt

[mstacy]

Thanks for the ideas.

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