[Tim Harrigan]

Countymouse;17781 wrote:

I can see the spring rarely compresses more than 1 inch over the preset.

Andy, I thought you were targeting the higher end by selecting the preset level. It seems like you would not expect to see a lot of spring action by doing that. And, maybe I am not remembering correctly, but didn’t you fall in to annoying harmonic oscillations of the spring when the pre-set was set too low for the load? That hitch uses two small springs, one on each singletree rather than a single larger spring. Maybe they are targeting the lower end and the starting forces.

[Tim Harrigan]

Countymouse;17781 wrote:

The picture doesn’t look like they were pulling a wagon with this set-up, there is no breeching and it looks like the horses are to be attached to whatever they are pulling with a dragging chain. I would have guessed this to be a heavy dragging load, maybe a log?

I also am curious about this tack and how/what it is used for.

[Tim Harrigan]

My guess would be a relatively light load buffer, probably for wheeled vehicles. Looks to me like it might buffer the start and lower range peaks. I would expect to bottom out most of the time with skidding loads.

[Tim Harrigan]

John, you make a good point and I agree that it certainly is possible to have unintended consequences when making these modifications. I have already explained and have shown situations where, at least with the draft buffer I used, there are situations where buffers can actually be a drag on the system. Andy explained seeing harmonic oscillations that he interpreted as annoying to his horse, so buffers can also be counterproductive. I have seen other cases where the buffer was no benefit and in at least one case a buffer reduced draft almost 20% with no negative consequences. So there are a lot of possibilities, we just do not have many practical guidelines for selection and use of a draft buffer.

The challenge is that horses and oxen are effective in buffering the effects of draft so it is really hard to visualize or confirm the impact of a buffer. It is hard to watch a team and draw defensible conclusions because unless you are working near the edge of their capability they do not seem to reveal a lot. Part of the problem is that we can’t see the nature of the forces pulsing through the traces or towing chain. Even when we can get a look at the forces such as in the graphs I showed it is quite a challenge to interpret them in a practical and meaningful way because the animal can only inform us by it’s behavior. And, that assumes we can correctly interpret the behavior.

This thread has been about discovery. I like the turn it took from a display of forces generated to the practical implications of modifying those forces to linking and interpreting changes in animal behavior in response to those modifications. Andy’s work has the potential to be very informative. But we are still working around the edges of the bigger picture. Proper harness or yoke fit and design, hitching, conditioning and reasonable expectations have potentially a much bigger impact for our community of interest than a draft buffer. There is a possibility that in some hands a buffer could be another excuse for poor management or a lack of skill.

A draft buffer is a tool that could have a place and value in easing the burden of our draft animals by improving animal comfort and productivity. But it has to be practical. I think there is a certain practicality in a buffer for shock load protection, and perhaps in trimming peak pulling forces above a pre-set level. That practicality means the buffer will not be in action very often. I think it would be possible extend those benefits to a wider range of pulling forces but at the cost of more management and fussing around. There is value in that in the discovery process, but the practical use drops off. I don’t think anyone is suggesting everyone needs a draft buffer but there is potential value for many situations. We can still learn a lot with some fairly simple measuring of pulling forces coupled with close observation of behavior.

The better we understand the nature of the forces that are transmitted to our team and understand how our team responds to those forces, the better we can demonstrate our trustworthiness to them. That will be returned many times over by the trust they demonstrate in us.

[Tim Harrigan]

near horse;17688 wrote:

– in the TB vs Draft horse comparison while both had similar peak force-speed , the draft achieved it at 2 m/s (~ 4.5 mph) vs 5m/s (~ 11mph) and the experimental treadmill couldn’t be set any slower than 2 m/s. Perhaps the benefit of the draft animal is the force generated at low speeds – much more practical for farm work.

The typical travel speed for drafts for farm work is about 2 mph, about 1.75 mph for oxen. So the treadmill really was not representative of typical work. I have not read the article, not sure if it makes any difference.

[Tim Harrigan]

When I measured the draft of a springtooth harrow on ground that had been plowed in the fall then disked in the spring the draft was very sensitive to depth of tillage. We used a 22-tooth harrow and a map of the tillage draft across the field is attached for 2-inch and 3-inch depth. We did some measurements at 4 inches but I thought it was unreasonable to ask the team to work at that level for very long. On a per tine basis the average draft increased from 19 lbf per tine (418 lbf for us) at 2 inches to 28 lbf per tine (616 lbf for us) at 3 inches to 45 lbf (990 lbf for us) at 4 inches. The frequency chart shows the frequency of pulling forces in 100 lbf increments for each tillage depth.

I have noticed that folks just really like to bury those tines in the ground but there is really no need for it. At 2 inches you get reasonable leveling, breaking of crust, sizing of soil clods and uprooting of weeds. At three inches you get all of that plus you pull up buried residue and dry out your seedbed. At 4 inches you get a dried out seedbed and a tired team.

The left half of the field was harrowed at 2 inches, the right half at 3 inches. The high draft area in the southwest corner was were we started picking up and dragging some sorghum residue that fell into the field from the field next to this one. The really high draft in the northeast corner was with the tines set at 4 inches.

[Tim Harrigan]

Countymouse;17680 wrote:

I had thought the average draft on this load might be 368 pounds (920*0.4), which would only decompress the spring when the load is exceeded by 108 pounds ((4*119)-368), a nearly 30% increase. Perhaps because the trail is muddy in parts and full of ruts the draft is not best estimated by simply multiplying the weight by 0.4 it seems substantially higher… My thought was that reguardless of the terraign, I can vary to load, observe the behavior of the spring and the horse, and later “zoom in” on load and spring ranges that seem to warrant further observation.

I like the fact that you have visual and audio ques to help you assess the action of the buffer. I did not have either with the nylon tow rope. The 0.4 rule-of-thumb applies on firm, grass covered pasture or hay ground, level. It can easily vary from .3 to .5 as you do to other surfaces so if you are on a surface that offers more resistance it could easily .5, maybe more if it is soft and you are tilling ruts. A sled or scoot will be more variable than a flat bottom stoneboat particularly in soft soil or muddy ground. Because the weight of the scoot or sled is more concentrated on the runners it tends to cut in more so you not only have the resistance of the implement but the tillage effect as well. A flat bottom stoneboat will increase also, but not nearly as rapidly as a sled.

[Tim Harrigan]

Good report, Andy. It is really hard to assess these draft buffers unless you have some quantitative measures to compare. I like your attention to the signals your horse is sending, if it turns out we can do some actual measurements that confirm what you suspect is happening you will have more confidence in your interpretation.

It looks like at 4 inches the buffer is set to act at just about the average pulling force. You must be seeing a lot of action at that point. Does that seem favorable?

[Tim Harrigan]

Good luck with the calves, get all three if you can. Its great to be home, isn’t it?

[Tim Harrigan]

Countymouse;17639 wrote:

… Tim, on the graphs you generated for starting a load, were the horses starting with a “double leg thrust” or simply “walking off”?

I don’t remember watching for that specifically. My guess is with that load they used both legs, at least for the first stride.

[Tim Harrigan]

Countymouse;17622 wrote:

… maybe the spring could be tested on your team at your place. I wouldn’t mind mailing the spring to you for testing and we wouldn’t have to wait until June to see what happens…

That might work. I am trying to make it work with new software right now, if I get it working reliably I will let you know and we can work it out.

[Tim Harrigan]

Don’t take my comments about Jason’s horses being able to hang there and cross on two feet too literally. What I mean is they are able to dig in and push into the collar without having to counteract the downward rotation that there would be if the line of draft was too low. It is more with the efficiency of movement and the ability to balance and channel all the effort to the goal at hand.

[Tim Harrigan]

Carl Russell;17613 wrote:

How would you guys feel about me approaching RH or SFJ about publishing this thread?
Carl

I guess if it contributes to discussion and continued education of the broader community of interest it advances the main benefit of DAP. Any proceeds could support continued availability and access to the site.

[Tim Harrigan]

Thanks, Kevin. I had not seen that site but I think they are a variation of the Pinney spring buffers that John mentioned. It would be interesting to test them but a bit pricey at $165/pair plus shipping.

[Tim Harrigan]

What I like about Jason’s skidding pic is that the 4-up is pulling so well together to move a big load and it also shows in action some of the things we have been discussing. The wheel team has a pretty good draft angle on the arch, not quite as great as a choker on the log, but the arch provides lift and some other benefits that amplify the effort in moving the load. The front team has a higher hitch because of the linkage to the wheelers. You can see how that alters the line of draft to less than perfect (a low draft angle) but you can see that team knows how to work with what they have.

The other picture at a pull is a great example of a perfect hitch angle. The line of draft runs right through the balance point at the center of gravity. The balance is so perfect that it looks like the team could just hang there while they dance across the line on their hind feet. Great stuff, Jason.

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