Horsepower needed for plowing

Seems like I once saw somewhere that a general rule of thumb for horsepower needed for plowing was 1 Hp. per inch of plow.

So if you had a 12" 1 bottom plow you would need 12 Hp.

For 2-12 would need 24 Hp. and so on.

Would that be a safe yardstick to use?
 
Our soil is a little tougher than some areas. I figure 20-25 pto hp per 16" bottom. Here a Farmall M would handle 2-16", or a 4020 would pull 4-16. They would pull it in any conditions, in easy plowing could probably pull a little more plow.
Josh
 
One year I pulled a 4-18 with an 85hp tractor. Was a nice easy
fall. Very rare I could do that.

Some years the same plow will pull the front end up on my
140hp tractor, really make it snort.

My soils plow tough. Lot of areas need less hp per bottom.

A plow is designed to go 1/2 as deep as it is wide per bottom.
So in theory a 3-14 plow moves less dirt that a 2-16 and
should pull easier. That's a theory, not sure it works that way in
the real world.

Paul
 
We always figured 15 for a 14" plow and 20 for a 16. Dad's MF 135 did good with 2-14' and my 4020 did good with 4-16'. Neighbors tried 4-14's with a 5000 ford and a 3020 JD, but not real well, just barely enough power to plow not real deep. Neighbor had a JD 730 gas and it was amazing. It would eat any 3020 around here for lunch with a plow. One local farmer bought a new IH 706 diesel in about 63 or 64 with 5-14's and with in a week took one off.
 
You need to consider more than the tractor HP. Tire type, wheel weight, gearing and front wheel assist are factors to consider. Also the type of soil being turned and the plow depth would make a big difference. An 8n Ford could pull a 4 -12s in light sandy soil if the tractor is weighted correctly and in good running condition. It might have difficulty pulling a one bottom 12 in heavy wet clay.

Another factor to consider is that different plows pulled harder than others. Some claim that JD plows pull harder than Oliver or Ford plows.
 
Soil type and structure make a difference.

Plow (brand) may make some difference.

Plow (type) will make a difference.

Ground speed will make a HUGE difference.

I've seen (in the same field) a 70HP tractor handle 5X16"'s (@ relatively low speed and a LOT of ballast) and a 60HP tractor struggle with 3X16"'s.

Some plows are designed as deep draft bottoms, then there's mounted plows, pull type, and semi mounted... Some brands have different contours to the moldboards, which will pull harder/easier than others.

My dad and his brother owned IDENTICAL 4020's back in the '60's. Both dynoed 98hp at same rpm. Both weighted the same. With same EXACT plow (145H Deere 5X16) dads tractor would walk off and leave my uncles tractor. The ONLY difference was the brand of tires on the 2 tractors. That made dads tractor SEEM to have more ability to pull a load.

Tons of variables.
 
I pull 5-18 with my john deere 4320. It's all it wants hp and
traction wise. They're rated at 115hp, but I was told this one
was tweaked a little. Mid michigan area.
 
Back in the day, Case plows were believed to pull easier than other makes, possibly because of moldboard design.

I don't have any personal proof, but my father-in-law had a Case 3x16 pull type and when he had his auction in 1978 a half dozen guys were after it and it brought twice what any other 3x16 would have.
 
(quoted from post at 13:15:17 02/26/15)

A plow is designed to go 1/2 as deep as it is wide per bottom.
So in theory a 3-14 plow moves less dirt that a 2-16 and
should pull easier. That's a theory, not sure it works that way in
the real world.

Paul

3*14=42 inches

42*7=294 square inches of soil moved

2*16=32 inches

32*8=256 square inches of soil moved

Whether you look at linear cut width or square inches of soil moved, the 2-16 is still moving less soil.




Beyond everyone's experiences, I think if you looked at the bulk density of the soil (compare a clay soil to a sandy soil), and the horsepower required to move that soil, you would see the wide range of horsepower that is required.
 
It's probably as good a rule of thumb as any. The comments below should pretty well cover the other considerations. I can tell you from personal experience that a 5x16 semi-mounted Oliver takes very little more hp. than a 4x16 semi mounted JD. Never had any personal experience with Case plows, but a neighbor pulled a 6 bottom Case plow with the old style 830 for years. Don't know if they were 14's or 16's and I don't know how deep he plowed, but he had hills and low wet ground, too, just like we did.
 
There is no universal 'rule'. It all depends on soil
type and some other less significant factors.Her in
our heavy tight irrigated soil at 5200 ft
elevation,we figure 25 to 30 horse per (16")
bottom.I plowed one field(old pasture) last year
that probably needed 50 hp per bottom.10 miles west
of me they can pull one more bottom with the same
tractor.
 

Soil conditions make a whale of a difference in power required.
If the soil has the right amount of moisture it usually turns best.
Too dry and some soils are hard as concrete.!
One farm of ours has Black Wax and the best time to plow that is in the Fall, when there is nearly some water in the furrow.
The Yellow Wax is sticky and gummy and hard pulling at best, and you don't want to try plowing it too dry..
Both types can be so hard when too dry that the tires will leave rubber on the soil surface and not leave a mark from the tread..!
The clay ground is pretty easy pulling around here, tho..
 
Our soil has some clay in it so to successfully plow you need about 15 hp per 14". You can do a much better job with more hp.
 
I think you need to double that around here. We pulled 3x14 with 85hp then went to 4x18 on 130 and now 120 on the 4x18. The only one that had enough power was the 130 on 4x18.
 

Exactly 2 Hp.... LOL could not resist.
a184500.jpg
 

Depends on the tractor, tires, weight etc.

A 50 HP yuppie hydro tractor on industrial tires won't pull what a 50 HP utility on ag tires will.
 
Tractors were rated to pull oversize plows. Take the all fuel John Deere A, 41 to 52 rated at 29 MAX PTO HP and was rated for 3-14" or 2-16". Around here in northwest Ohio 2-12" for that tractor. Now the 47-52 gas version at 38HP will handle a 3-12" OK. I figure 13 HP for a 12" bottom, 15 HP for a 14" bottom so that 3-14" that they rated tractor at 29 for actually needs 45 or the 2-16 actually needs 40 HP as a 16" bottom needs 20 HP per bottom. Remember the 12" bottom is designed to plow 6" deep, the 14" bottom if for 7" deep so you not only have a 2 x 7" on extra width but a 1 x 12" strip extra across bottom so you are turning a total of 72 square inches with the 12", 98 square inches with the 14" and 128 square inches with a 16" bottom and with an 18" bottom 162 square inches. So not only does the extra width take more power you are also with the wider bottoms going deeper so there it also takes extra power. If you could stay the same 6" deep with the 14" or 16" bottom it would stay theoriticly the same 1 horsepower per inch width of cut but that 1 HP per inch of cut is on the low side. Very easy plowing you could get by with that. Better for that 2-12" plow would be 28 HP, not 24 but go to a 3 bottom and it takes less per bottom to pull as less power to move the outfit per bottom, 4 would take less per bottom than the 3 and so on. The 9N Ford was 23 HP so it with a mounted plow and a lighter weight unit could do about the same with that 2-12" as the 28 HP Deere with a 2-12" drag type because of the different weight. That is Why the NAA Ford at 32 HP could pull the 3-12" about the same as the 38 HP Deere with the same size 3-12" on 38 HP.
 
Soil type makes a huge difference. If I went 10 mile south out of my driveway a super 88 Oliver would have a full load with 2-16's. Turn the other way and head up north 10 miles to the sandy ground and a super 88, super M IH or a John Deere 70-720 would pull 4-14's.
 
It all depends on soil. I own what is reputed to have been a 3-4 plow tractor. On my clay I can make use of a 2-14, don't plow too deep and I'm standing on the diff lock or riding a brake quite often. I generally have to put the double ring chains on if it starts getting wet too. Not a fun farm to plow at all.

Local story is that back in the late 50's a local tractor dealer about 15 miles away got mad because he had several complaints from customers who bought a 45ish hp tractor from him to use on our clay. He sold them 3-12 plows and promised they'd plow anywhere with those plows. Finally he got fed up because the complaints were hurting his business and scheduled a field demonstration on a farm in our town to show the locals here how a real man that knew what he was doing could plow. On the big day there was a huge crowd (by our standards anyway- 45-50 people) and he set out to plow a field. He made it about 15-20 feet and came to a dead stop. He fiddle farted around for about 2 hours before admitting defeat. After that tractors sold in our town got a 2-12 set of plows and the dealer came out to set them up correctly. I understand some farms got 2-10's! I have a set of 2-10's said to have come from that decision.
 
You got some realistic advice here. Most plow threads end up being one big fish story, where people boast about their stock Farmall M pulling 6-18's sunk 12" deep in the ground in road gear.
 
Thanks for all the replies guys.

I asked because, while it's not a Farm Tractor, I have a Large Frame Bolens Garden Tractor with a 23 Hp. Mitsubishi Diesel in it. That's the HP at the engine, so we know that it's less than that at the drawbar.

It weighs in right at 2000 Lbs. with me on it and ready to plow. I can pull a 1-12 with no problem. I'm thinking of maybe trying to pull a 2-10 and was wondering if I was in fantasy land or not.
 
Going from 1-12 up to 2-10 is a very big jump, 66 percent if you stay at the same plow depth. A smaller jump from 1-12 to 1-14 (17 percent) might turn out to be more than you want. You still want to moving at a steady clip without lugging the engine or excessive wheel slip. Often you can cover more ground with smaller equipment moving at a fast steady speed than you do spinning and lugging trying to pull too much.

How many acres do you need to cover in how much time? Sixty year old 30 HP to 50 HP tractors and 2 or 3 bottom plows are less expensive than newer garden sized models.
 
You theroticly are cutting a slab of soil that is 72 Square inches with the 12" cutting its designed depth, now a 10" bottom has a design depth of 5" so a furrow slab would be 50 square inches so a 2 bottom would be turning 100 square inches or 28 square inches more. But remember the garden tractors of back in the 50's-60's were at most about 8 horse engines and they had a 10" plow for them. You should be having a mounted plow on that outfit and if you could make up a 2-10" using a pair of garden tractor plows for that you might be able to pull it. The garden tractor plows were a lot lighter than field plows of the same size. 1 horse could pull a 10" walking plow, takes 2 for a 12" walking plow, now go to a 12" sulky plow and you need 3 horses. The difference between the 12" walking plow and the 12" sulky plow is the extra weight of the sulky and driver. Is this just for show or are you trying to get depth for planting a crop?
 
I would just try it. Just for fun.

My Super C pulls a 2-14" fast hitch plow in my soil with no
problem. It's about a 20 hp tractor.
 
If it's for plow days I'd leave it as-is, keep pace with everyone else and have fun.
 
(quoted from post at 11:49:49 02/27/15) Thanks for all the replies guys.

I asked because, while it's not a Farm Tractor, I have a Large Frame Bolens Garden Tractor with a 23 Hp. Mitsubishi Diesel in it. That's the HP at the engine, so we know that it's less than that at the drawbar.

It weighs in right at 2000 Lbs. with me on it and ready to plow. I can pull a 1-12 with no problem. I'm thinking of maybe trying to pull a 2-10 and was wondering if I was in fantasy land or not.

I'd stick with the 1-12 and be happy. You might get real embarrassed if someone sees you trying to pull a 2-10.
 

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