[Tim Harrigan]

Here is the graph I used in the logging draft bulletin. Flat tires are a pain for sure, but you will be asking a lot more from your team with steel tires. Draft with the pneumatic tires ranged from 4% to 9% of GVW, the steel tire wagon draft ranged from 9% to 16% of GVW. Steel tires do not deflect under a load so they sink in until the carrying capacity of the soil equals the downward pressure of the tire. Rubber tires deflect and increase their surface area under load so sinkage is less. Less sinkage means less motion resistance. You can see here that on the hard surface of the gravel road (mostly hard-packed sand) the average draft for the steel tires increased 115% compared to the pneumatic tires. On the hay ground, more irregualar surface, some sinkage but barely noticeable, 79% increase, and on the firm soil that was soybean stubble ground from the previous year early in the spring, the steel tire average draft increased 56% compared to the rubber tire. The background picture shows how the steel tires were cutting into the ground. It takes energy to compress that soil to move the wagon over the surface.

[Tim Harrigan]

OK, this discussion is drifting off topic so I will take this to a new thread.

[Tim Harrigan]

mitchmaine;17251 wrote:

are you saying then that the spring, with stretch somewhat like the nylon, might develop a higher draft?

I suspect it will based on what I have seen with the nylon rope system. I am not speaking against the spring buffers, it is just that they are best selected to protect against shock loads. That means occasional and uncharacteristically high loads such as hitting a rock when plowing. So if you are using one and you see a lot of spring compression or extension, depending on the type of buffer you have, perhaps it is undersized for the operation you are doing.

[Tim Harrigan]

Looks good. Maybe they can measure the hp output sometime. That would be very interesting. There were a few questions/comments about such a machine on this site not too long ago.

[Tim Harrigan]

I agree that the greatest benefit of the springs is to protect the equipment from shock loads such as when hitting a rock when plowing or maybe when catching a root when skidding a log. I have not seen any evidence that they do much to reduce high-end draft forces under normal conditions. I have compared draft forces for standard harness (horses) and tow chains (oxen) with nylon tow rope and generally I have measured higher forces with the nylon tow rope (I am not referring to the nylon rope and pulley systems). Why this is so is sort of a long story but I will get into it later when I have more time.

I think the buffer springs can be a good idea but you do not want to see them extending very often.

An example of the higher draft with the nylon tow ropes is in the graph and picture I posted some time ago in the Sustainable Forestry section under ground skidding. We did some side-by-side skidding over a ton on a scoot uphill, on level ground and downhill with standard traces and the nylon rope. It is surprising how much higher the average draft is with the nylon. If you look closely in the picture you can see the nylon traces.

[Tim Harrigan]

Countymouse;17237 wrote:

I noticed that the chart plots everything above 700 lbf as one event. I am curious what the maximum force you recorded in this run or other runs… In the same vein, it seems that a spring hitch (like the ones used on some of the pioneer sulky plows) could “smooth out” some of those higher draft spots. I am interested in hearing opinions about the use of these springs and if they help much in the real world…

The maximum pull with that plow on that day was 821 lbf. Your question made me think of some plowing we did with a 14-inch sulky plow in the fall one year after it had been really dry for an extended time. It was on a Kalamazoo loam but I am sure it would texture out as a sandy loam. The average draft in this case was 1002 lbf and the maximum pull was 1692 lbf. We used two teams of oxen and they had their work cut out for them and they did a great job. I will attach two images, one is a draft map showing the spatial distribution of forces across the field, the other is a graph of the frequency of forces similar to the one for the walking plow. This is based on 5,100 measurements of the plow draft.

Notice the pulling forces for the plow on this hard, dry soil. The highest forces for the walking plow were in the 700 lbf range, the lowest forces for the sulky plow were in this range. I would normally expect the average plow draft to be in the 700 to 800 lbf range on this soil. Plow draft is hard to predict because it is so strongly influenced by soil conditions.

This is why a team has to be prepared to pull a plow. An equivalent sled or scoot load would be 2500 lbs.

[Tim Harrigan]

Those are all great suggestions. Geoff, yes, usually someone drives the ox team and another person plows. Not required though if you have a well trained team.

[Tim Harrigan]

Those are good suggestions for understanding the mechanics of the plow and it will certainly be helpful if you can work with an experienced plowman. There are quite a few plow days around this time of year, make a point of visiting a few if you can. It is not clear based on your description how you have been using your team. I work with oxen and two of the things I would want to have confidence in are 1) are they prepared to pull the load created by the plow, and 2) do they understand what it means to follow the furrow. Plow draft can be highly variable so it is difficult to predict what normal plowing is in your area. If you have a 12 inch plow and run 6 or 7 inches deep the pull will typically be about 600 to 800 lbf. It is good to condition the team this early in the year for that level of effort. If you improve their condition by building up a load on a sled or stoneboat to 1500 to 2000 lbs they will be ready for plowing. That load with be about the same as the plow load. Also, the furrow-side horse will need an introduction to walking in the furrow. They will probably pick that up fairly quick, but respect that it is a new skill if they have not done it.

[Tim Harrigan]

Must be a regional thing. I my part of the world they are called SAV’s, suburban assault vehicles. You mostly see them parked near where you want to go and taking up 2 parking places.

[Tim Harrigan]

I really have a hard time using elite and Hummer in the same sentence. Can we just use ‘out-of-touch’ or ‘self-absorbed’ rather than elite?

[Tim Harrigan]

Rob FLory;17046 wrote:

Chris still holds his head down no matter what I do with his bows so I am calling that his own personal problem. /quote]

Rob: My off ox Abe has always done the same thing no matter how I adjusted the bows. I assume it is a personal preference and stopped worrying about it. When the behavior becomes a habit they are much less responsive to equipment changes and it gets harder to identify cause and effect. That assumes, of course, that the equipment is not causing pain. So you can not always assume that because an ox carries his head low that it is because the bow is set too high.

[Tim Harrigan]

Yes, that was a good conference. Were you there?

[Tim Harrigan]

It is really just a minor issue for clarification on my part. Still trying to mentally calibrate that log and betting it was a good 4000 lb.

[Tim Harrigan]

Carl Russell;15597 wrote:

The butt log, being 10′ long, and probably at least 30″ will scale around 300-325bf, which at 11000#/MBF for NRO, should put it near 3500#,
Carl

Carl, with your rules-of-thumb for timber density do you allow for likely moisture of the wood? I was looking at the USFS info and they list red oak at 63 lb/cu-ft green and 46 lb air-dry. Based on your description of the butt log I figured 70 cu-ft so on the ground at 3200 to 4400 lb depending upon if it was alive when it fell and how long it had been laying there. Does the 11000#/MBF refer to sawn lumber, what is in the log, rather than the log itself?

[Tim Harrigan]

Good idea. Then you can let us know what you find out. Maybe green/steam/bark and green/steam/bark/band as well. If you have the bands and a steam box use every trick you have. It is a lot of work to have it fail.

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