Disc Harrow Selection For 18-45 Horsepower Tractors (Revision 2b)

[jeff9366]

Earlier, on another thread, I remember reading about a technique to prevent the discs from picking-up soil which sticks between - and gets packed in tight. It involved chains, but I can't locate the post now.

Here 'tis:

Like others have said, the ground is too damp. Scrapers will help if the disk has a place for them. Sometimes if the problem is just with the rear or just a problem at certain locations, you can place a piece of light chain around the frame and between the discs. Some of our older, smaller, farm discs would have this problem, especially near the tractor wheels or on the very outer discs where it would be near the just tilled/wetter dirt. The chain will prevent the dirt from forming a complete union between the discs. Trust me it does work. If you wanted, you could place chains between all discs. Don't make the chain tight, just leave it hanging loose so it doen't wear on the axle.

 

[newbury]

I may have missed it but what's a "horsepower?"
The disc doesn't use the PTO so it might not be a "PTO horsepower", but it's "ground engaging equipment" where engine horsepower often is not used.

My M4700 "engine" is rated at 50+HP on Tractordata and Tractorhouse, 47HP in the manual
PTO is 42HP for all three.

So are you talking engine hp?

 

[vtsnowedin]

I may have missed it but what's a "horsepower?"
The disc doesn't use the PTO so it might not be a "PTO horsepower", but it's "ground engaging equipment" where engine horsepower often is not used.

My M4700 "engine" is rated at 50+HP on Tractordata and Tractorhouse, 47HP in the manual
PTO is 42HP for all three.

So are you talking engine hp?

Pulling a ground engaging implement you are talking about the drawbar pull. That takes into account all losses between the engine and transmission and rear end gears. You have to have sufficient traction from the tires and ballast to convert the tractors power to forward motion but given that the more engine HP you have the more of it you can get to the draw bar.

 

[motownbrowne]

I may have missed it but what's a "horsepower?"
The disc doesn't use the PTO so it might not be a "PTO horsepower", but it's "ground engaging equipment" where engine horsepower often is not used.

My M4700 "engine" is rated at 50+HP on Tractordata and Tractorhouse, 47HP in the manual
PTO is 42HP for all three.

So are you talking engine hp?

It's too bad that drawbar horsepower isn't listed anymore. I think in the conversation we're having here, 5hp per foot is kinda vague. Honestly, for pulling a disc, HP is only as good as traction, and thus weight and tires. For example, an 8n with loaded ag tires will pull a disc better than a b series Kubota with r4s any day. A b with loaded r1s and weight up front might be closer, but without knowing the drawbar HP it's hard to know. From looking at specs of international hydro's it seems that drawbar HP seems to be a around 75% of PTO HP. I don't know if modern hydro's are any better. So, a 33hp b might be have only 18-20 HP at the drawbar.

Luckily, you can buy a Farmall h or m for a song and have all the drawbar HP you could want. Those old narrow fronts are still really good at what they're designed for. An M claimed 25 HP at the drawbar (not much more than the b) but can pull a 10' disc with no problem.

 

[newbury]

Thanks, I was just looking for clarification by the OP.
With the "5HP/foot rule"
My M4700 with 52 engine HP could pull 10' of disc
My M4700 with 42 PTO HP could pull 8' of disc
My M4700 with 30 drawbar HP could pull 6' of disc

Six to ten foot is quite a range.

 

[vtsnowedin]

Horse power is a "rate "of work so speed is a factor. Having a given horse power combination assumes it is doing the job at a reasonable speed. If you have on more tool then your tractor can pull at that speed you can drop down a gear or two and do the same work but over more time right down to where you don't have enough tires and traction to move ahead at all.

 

[motownbrowne]

Horse power is a "rate "of work so speed is a factor. Having a given horse power combination assumes it is doing the job at a reasonable speed. If you have on more tool then your tractor can pull at that speed you can drop down a gear or two and do the same work but over more time right down to where you don't have enough tires and traction to move ahead at all.

True, but there's other factors, in this case the disc won't do it's job below a certain speed. Discs and plows require a specific rate of travel, so even if I could pull a five bottom plow with my 8n in low gear and low range (Sherman transmission) it wouldn't do the job because the soil wouldn't turn over all the way. I'm not disputing how HP works, plenty of threads for that already, just talking about how the disc works.

@Newbury, I'm not sure if you're actually curious, or just making a point, but HP (especially at the flywheel) isn't going to be your determining factor here. First, weight and tire type is the main factor. Then, likely, soil type, whether you're cutting pasture grass or established ag fields, also, pull behind disc, or three point, and whether you're tractor's geared or hydro.

Yes, 6-10 or even 12' is a wide range, and you'd likely be able to handle many discs in that range depending on your task.

 

[jeff9366]

The disc won't do it's job below a certain speed. Discs and plows require a specific rate of travel, so even if I could pull a five bottom plow with my 8n in low gear and low range (Sherman transmission) it wouldn't do the job because the soil wouldn't turn over all the way. I'm not disputing how HP works, plenty of threads for that already, just talking about how the disc works.

Here is a picture showing ground tilled by my 16/18" Howse Disc Harrow pulled at a brisk pace.

The soil thrown out by the front gangs is clearly visible, as a lapping wave nearest the tractor. The little furrows are where the ouside pans of the rear gang picked up soil to throw inward. Combined…..good mixing.

Location is a firebreak surrounding a community burn pile which I maintain vegetation free.

 

[vtsnowedin]

True, but there's other factors, in this case the disc won't do it's job below a certain speed. Discs and plows require a specific rate of travel, so even if I could pull a five bottom plow with my 8n in low gear and low range (Sherman transmission) it wouldn't do the job because the soil wouldn't turn over all the way. I'm not disputing how HP works, plenty of threads for that already, just talking about how the disc works.

.

That"s all true enough and then there is soil type and moisture content. What you can pull (and roll over) in well drained sandy soil is a lot more then what you can pull through a sticky clay soil. Add enough clay and water and no matter how big the tractor you are stuck.

 

[LouieJunior]

The chain will prevent the dirt from forming a complete union between the discs. Trust me it does work. If you wanted, you could place chains between all discs. Don't make the chain tight, just leave it hanging loose so it doen't wear on the axle.

Thanks Jeff -

Do I create a loop with the chain -- connecting the ends, or connect loosely around the axle with an end dangling between discs. Also, what size of chain?