HP required to pull plow

dhilbert

Member
I ran across a 3-14 semi mounted plow the other day, I was wondering if a 511b would pull it. Growing up we had a 4-14 plow same model that we pulled with a big 400. Thanks Dan
 
You will need about 9.5 drawbar horsepower per 14" bottom to pull a plow at 5 mph (assuming that plow is designed to be pulled at 5 mmph). You will also need about 2200 lbs of weight on the drive wheels per 14" bottom. This is assuming that you are working difficult ground that is prime for plowing, assuming that everything is adjusted correctly on the tractor and the plow, and assuming that all of the plow parts are in good condition.
 
The 511 has more horses than a 300 roundnose and we used 3-14"s behind that in all kinds of soil and some hilly areas. You shouldn"t have any issues as long as you have some wheel weights.
 
Here is my plow size rules.

Forget the ego and forget trying to impress the neighbors who have green tractors. Ha

Use at least one less bottom that the tractor's rating.

The small plow allows plowing tougher ground.

The small plow allows plowing deeper to get rid of compaction

The small plow allows the tractor's land wheel to have enough traction to plow in wet falls.

The small plow takes up less room in the barn.

The small plow takes less time to grease the bottoms when done.

The small plow has less rusted bolts and less part to replace and less rolling cutters to adjust. I need a real job. Ha.
 
we always figured 20hp per bottom. this took into account wet spots, clay and speed of plowing. plowed with 3-16's on an 830ck diesel for years in 4th low about 1/2 throttle. plowed all day all night i'm in upstate ny
 
I do have to drive father and that takes more fuel so your point is well taken.

I am curious what tire slip you factored into 2200 lbs per bottom and how you divide the weight between the furrow tire and the land tire.

A tire cannot produce traction without slipping. For heavy field work and not running in a plow furrow, tires typically slip 20 to 25% and belt tracks slip 4 to 6%. Slippage is a pure waste of fuel.

I only have so many wheel weights. Every weight I got goes on the land wheel even when pulling the smaller plow. Even so, observing the tire tracks for wheel slip makes me want a lot more weight on the land wheel. The furrow wheel seems to have low slippage maybe 10% but the land wheel slippage is out of this world. The differential takes a beating.

But then my plowing is not typical so I suppose my rules don't apply. Ha! My 1170 is set at 146 hp and I had to pull in the 12000 lb class tractor pull years ago when I last weighed it. With a ton of weight added to the land wheel and 6 weights on the front, I must be running about 14000+ lbs and pull 4 16s semi mounted.

I raise the plow in the bottom of draws to minimize the draws getting deeper from erosion but I expect to plow tough clay uphill out of the draws 12 inches deep. I expect to grow good crops in these areas and deep plowing helps a lot.

I suspect that I am not the only one who has tough clay on the sides of draws. I would be curious how others plow this situation and what the yields are on their draw slopes.

When we play plow with my antique DC's, we have to stick to about 6 inches deep for the draw slopes.
 
I find that the power required scales proportionally with the frontal area of the soil being moved (assuming everything else stays the same). Thus, it takes about 1/10 hp per square inch.
 
I figured about 15% slip on both wheels into my 2200 lb estimate. Of course, soil type and field conditions make a big difference here. The sandier/looser the soil, the more slip is desirable. In sand, you want 30%+ slip, and you want 0% on pavement. Also, the wheel diameter/tread width ratio, power/contact area ratio, down force/contact area ratio, tread pattern, soil moisture content, soil type, etc. dictate the maximum slip that you can achieve before getting stuck.
I attempt to evenly distribute the slip between the two tires. However, conditions make a big difference here too. Sometimes the furrow wheel wants to slip more and sometimes the land wheel wants to slip more. Of course, All my experience is with 40 hp tractors and smaller (and plowing depths in the 5-10" range), so weights are easy to add and remove, and wheel spacing is easy to adjust.
My comment on fuel efficiency was more directed at the efficiency of the engine. It should be no surprise that an engine is most fuel efficient when it is running at maximum load and speed. This is especially true of spark ignition engines, but is also true of diesels. Thus, you may give up roughly 25% fuel efficiency by running your spark ignition tractor at 1/2 speed. Diesels aren't as bad as this but follow the same trend at the extremes of their load/speed curves. (Have you ever wondered why large gas tractors have a reputation for being gas hogs? Really, they aren't. People just try to run them at partial speed with a miniscule load, and they get terrible fuel efficiency at low speed/load operating conditions.) Of course, a tractor must be in good condition to tolerate full load and speed operation for long periods of time. The typical antique tractor is not in good enough shape to try this without risking major problems.
My experience with plowing is nothing like yours. I have only worked flat ground of fairly uniform consistency. Uphill plowing obviously takes more power, and differing soil types/ moisture levels will force you to size the plow for the worst combination of conditions in order to get the job done.
 
Thanks for the good conversation.

I looked at the Nebraska test for the 4020 JD. On the pto at rated speed and power the gas version lists 10.53 hp hr/gal. and the diesel lists 14.53. The gallons per hour listed is 8.2 for gas and 6.4 for the diesel.

The gas engine is a big vacuum pump so it takes fuel to run the vacuum pump before any power goes to the flywheel. This is one reason the diesel wins big time on part load jobs such as hay baling. The vacuum pump factor become a very big fuel efficiency issue for highway vehicles.

For several years, I was pulling my 11 ft turf mower with a DC and the butter fly looked barely open. That meant high vacuum pump energy loss. I switched to a little diesel about the same power as the DC and my fuel consumption is way down.

Back to plowing, we know that leaning the tractor towards the furrow unbalances the load on the two drive wheels so the land wheel needs extra weight. I replaced the differential in my 1170 once and the rolling cutters take a beating in the tough clay if I am careless and let them run deep. After replacing some broken cutter blades, I adjust them to only as deep as needed to cut the trash.

For about 10 years I stopped moldboard plowing and went to chiseling. Soil samples of the top 4 inches were showing the P and K was high and the next 4 inches down were low in P and K. I went back to moldboard plowing trying to mix the P and K and lime into the top 12 inches.
 
Thanks guys for all the good info. I think I will work on the guy on price, and see if I can pick it up and give it a try.
 
All reciprocating engines are vacuum pumps (a better term is "volume pump"), but like you said, a diesel has no throttle to restrict the flow of air. Also, a diesel can have a larger (less restrictive) intake than a carbureted engine, since there is no need to keep the fuel vaporized in the intake runners to get good throttle response. Really, the throttle butterfly restricts the flow and makes the engine run almost like it would at a higher altitude where the air is thinner (only worse). As you know, the key is to get the throttle open. And the best way to do this is to match the implement to the tractor (and conditions). This is where draft control, COM, torque converter drives, and powershifts pay off. They all supply ways of changing the load on the fly to match conditions. This is especially critical for places like where you are, since conditions change so much from one area of a field to another.
I don't know the particulars of the 1170 and your plow, but in addition to adding weights to the land wheel, I can also offset the body of my tractor to the left by shifting the wheels to the right, and adjusting the plow to the right. As long as the tread width, and position of the plow relative to the right tire is the same, then it will still pull as straight as it did before. However, you will have more weight on the land wheel.
I don't really have to worry too much about soil chemistry, but I have been told that the valleys in upstate New York tend to be very gravelly with a thin top soil. Thus, chiseling deep only brings up more rocks, and plow-pan is a non-issue. I also know that moldboard plowing served two important purposes in the past. The first was to till the ground, and the second was to weed (this was a much bigger deal before herbicide resistant crops). I trust that you are taking full advantage of both of these functions.
 

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