Disc Harrows: Tandem vs. Offset.

[Poopdeck Pappy]

The diffence between the two types of discs harrows is that an offset disc will allow deeper penetration but it is harder to keep the soil level and the opposite is true for tandem discs. In a tandem disc the longitudinal force exerted by the disc blade is offset by the longitudinal force exerted by another disc blade on the oppisite side. This causes the disc harrow to tend to want to float. With an offset disc the tendency for the harrow to float is decreased due to no oppisite disc blade.

My experience is that an offset disc will always penetrate and plow better than a tandem, even when both are heavy duty. I don't know why, but your explanation makes as much sense as anything else I've heard.

 

[MtnViewRanch]

This is what we pull with our Sears SS12. At 992lbs per blade, it can be a bit much when it gets down to the hubs though. :sarcastic:

 

[Poopdeck Pappy]

This is what we pull with our Sears SS12. At 992lbs per blade, it can be a bit much when it gets down to the hubs though. :sarcastic:

I'll bet penetration isn't a problem with that one!

 

[jeff9366]

(( I have never heard of a towed Tandem Disc Harrow. ))

I SHOULD have written: (( I have never heard of a towed Tandem Disc Harrow appropriate for a 18-40 horsepower compact utility tractor. ))

 

[sixdogs]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil. Apparently the side action of the blades pushing against the soil is responsible. Don't blame me--that's what I have read.

 

[Gary Fowler]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil. Apparently the side action of the blades pushing against the soil is responsible. Don't blame me--that's what I have read.

Not saying the article was wrong just F.O.B.S. Clay or any other soil doesn't compact from disking. When tilling clay, it has to be done at the right moisture content. Too wet and you will have concrete like clods of dirt to contend with all year, too dry and it gets too hard to penetrate with any thing less than the one MtnViewRanch posted. I have never heard of anyone measuring side loading of soil and calling it compaction. Anytime any responsible person mentions compaction they are referring to vertical compaction which in farming is mostly caused by the tractor tires and occasional use of a sub-soiler or chisel plow to break up the hard pan takes care of that.

 

[jeff9366]

Each individual offset disc could be thought of as a heavy, concave, relatively thin, steel tire, unsupported by the soil surface, with a much higher loading per square inch than a pneumatic tractor tire. Below the cut soil you have compaction.

Harrow can cut/chop/throw/mix to the depth of the disc hubs, which may be ample for the root structure of the crop, but below bottom of the sunk disc(s) there is compaction.

Depending on local soil, of course.

In principle, ANYTHING which moves over the field, in contact with the soil, causes SOME compaction. Examples:
LS7010 tractor, harrow of any description, RTV900 utility vehicle, truck, horse, sheep, baseball, elephant, mice, snake.

Depending on local soil, of course.

Don't be mad, now, I am attempting a little levity.

 

[jeff9366]

Regarding soil compaction, all of the farm magazine articles I have read say that research shows the disc harrow to be the implement that does the MOST compacting of clay soil.

When do you find time to read outside TractorByNet?

 

[MtnViewRanch]

I SHOULD have written: (( I have never heard of a towed Tandem Disc Harrow appropriate for a 18-40 horsepower compact utility tractor. ))

Now you have. Here it is. Now it does not have any HP rating, but at 235lbs total weight, it shouldn't be much of a problem

 

[N80]

Now you have. Here it is. Now it does not have any HP rating, but at 235lbs total weight, it shouldn't be much of a problem

I doubt compaction is an issue with that one......penetration probably isn't either.....

 

[MtnViewRanch]

CHULETA, Brian, you continue to post the most interesting suppliers?

Are you sure its not a calf from the disc in your Post #22 ?

:laughing:These are all things that a person sees at the Tulare World AG Expo in California. You know that these manufacturers always want to show the extremes. The worlds largest disc which isn't weight wise, but is for width is pretty impressive at 60' in width. They claim in the brochure that 50 acres an hour can be tilled with it.

 

[MtnViewRanch]

I doubt compaction is an issue with that one......penetration probably isn't either.....

One of those implements that has no purpose because for it to actually work, the process has to already be completed.

 

[sixdogs]

When do you find time to read outside TractorByNet?

Speed reading, that's my secret. Read only one of every few words. I'm almost done with War and Peace right now. It's something about a dispute.

Actually, TBN in the winter is a wonderful thing as long as I don't stray into the political section.

 

[smstonypoint]

Speed reading, that's my secret. Read only one of every few words. I'm almost done with War and Peace right now. It's something about a dispute.

You know, War and Peace was originally titled War, What is it Good For.

Elaine

 

[Chilly807]

One thing no one's mentioned yet is the tendency of a tandem disc to leave a narrow strip in the middle of the gangs that isn't touched. Some have a cultivator type claw that takes care of that strip, others don't. The offset disc doesn't have that problem.
Some older tandem towed discs were actually articulated between gangs, the one I have was like that originally, although now it's been converted to a relatively solid 3-point type. One of the advantages to the solid frame is that it's much harder for the disc to follow the terrain contours, so it does a better job of penetrating high spots and leveling the ground.
One of the things I noticed after converting mine was that the front gangs penetrated much better than they had before, they had no choice other than lifting the rear gangs clear of the ground.

Sean