DRAFT CONTROL How does it work?

[Industrial Toys]

I have had this on a tractor since 1972, but I don't farm and have often wondered how it works.

Does it work? How does the system know what depth your implement is actually at?

What effect does this draft setting have if using your 3PH for other applications? I have never noticed a difference in operation.

Thanks

 

[bcp]

Draft doesn't mean depth in this case. It means pulling force, as in "draft horse."

Usually it doesn't know the depth. It knows the pressure at the forward end of the top link. When a plow hits resistance, the top link increases forward pressure, and the hydraulics raise it a bit so the resistance decreases, then it lowers the plow after passing the resistance. It tries to keep the pressure constant at the sensor mechanism.

Bruce

 

[k0ua]

The draft control does not know or care how deep your implement is. What it does care about, if you adjust the sensitivity of the draft control, is how much "draft" is applied to the lower links and how much pressure is applied to the top link when that draft increases.. as the implement becomes buried either too deep or hits a root or a rock this causes pressure inward on the top link. This applies force to a sensor, mechanical or electronic, that says the threshold you have set the sensitivity to by adjusting the draft control, has been exceeded, and it is time to apply hydraulic fluid to the 3pt cylinder/cylinders. This raises the 3pt and relieves the pressure on the top link when the "pull" or draft is relieved by going over the object or coming up out of the ground a bit.

The position control then lowers the 3p to its preset by the operator position, and the implement returns back into the ground at your preset position. This is mixed draft/position control. So to sum up, when the draft gets too high as sensed by the top link sensor, the position control is over-rode, the 3pt is lifted and returned back to its original preset position.

If someone knows more or can explain it better, please correct me.

 

[bcp]

Imagine a box blade that had the capacity to stall the tractor. When the load started to get too heavy, it would lift the blade to let some dirt out. The draft control would try to keep a constant pull (draft) on the implement.

Bruce

 

[Industrial Toys]

Does this mean the top link attachment point is not fixed?

 

[k0ua]

And the reason you have never noticed anything could be for two reasons.
1: you have never adjusted the draft control to the sensitive region. You normally don't do this unless you want the draft control to operate. For normal 3pt operation you leave it on "deep"

2: one or more of the top link holes will not make the sensor work at all. One or more of the holes will be "immobile" no matter how much top link inward pressure is applied. Your manual will tell you this. But the gist of it is, the top link holes are like a "lever" that on one end will apply a lot of force to the draft sensor, and on the other end no force or very little force. This is easier to see than explain.

 

[k0ua]

Does this mean the top link attachment point is not fixed?

Some of the top link holes are "fixed" and some aren't. see my above post.

 

[Industrial Toys]

So, a person plowing a field can see or sense a difference in these settings?

Our JD 6200 has only one top link. But I have a potentiometer. Probably the electronic equivalent of the multiple hole top link. Years ago, when considering a 3ph backhoe, the dealer warned me about some guy ripping the top link off the tractor with such an application. Would this be the reason?

 

[joefromga]

So if you wanted to smooth out some ripples with a box blade would it be better to use or not use draft control? Or just do multiple passes?

 

[Industrial Toys]

I guess, a question might be. Other then tillage, is there any other application for this feature? If not, I am surprised, (since cost seems to be everything), that ALL tractors seem to come with it, and that it is not merely an expensive option. Because, it cannot be terribly simple in design.

 

[joefromga]

Not terribly complicated I guess. Push a variable valve lever and it raises hydraulic then when the valve isn't pushed it goes back down. But you're right, for such a pinpoint usage you'd think it wouldn't be standard.

 

[Rustyiron]

IMO a box blade sitting on the ground has very little top link "effort" and I don't think would influence the draft control at all. It came on all of my tractors over the years, and have never hooked up to a more than a single bottom plow in a large garden situation. I have "played" with it and ultimately did not use it. I wanted a consistant depth (deep) turning of the soil. I think that their (draft control) origins were from the days of lower HP tractors and multiple 3pt. mounted plows. But that only a guess.
I would be curious to hear from someone that actually uses this function. It seems to me that they might as well put an 8 track tape player on a tractor, just as usefull:laughing:
I like k0ua's explanation.

 

[ovrszd]

I've used draft dozens if not hundreds of hours. My Kubota and Ford both have it. I've never used anything but mechanical draft. It's very easy to describe.

Older tractors (60s 70s) versions usually only had one control lever. A separate lever flipped the system into/out of draft mode. Later models use 2 levers. Let's talk about that method.

So if I want to use draft I place the normal use 3pt lever in the lowest position. Now I control the 3pt with the draft lever. Let's say I'm pulling a 3pt moldboard plow.

I determine the maximum depth I want to plow. I set the stop adjustment on the draft lever at that position. So everytime I drop the plow with the draft lever to the preset stopper, my plow will always plow at that maximum depth. How does it do that???

The top link assembly on the tractor is not rigid. It's usually mounted using a very strong spring. Somtimes using a compression system with a durable rubber bushing or some type of system that compresses and extends by the push/pull forces applied by the top link on my plow. Clear as mud right?

So I drop the plow with the draft lever to the stopper and start forward movement. The plow immediately heads for China (digs itself into the ground. This causes extension forces on the top link. The plow wants to go deeper. As this force increases it begins to extend the top link assembly on the tractor. As the mechanism extends it begins to move the controller inside the tractor toward the position of raising the 3pt. When the force is great enough lifting action stops the descending plow at the depth you previously determined. If the plow for whatever reason starts elevating above your preferred depth the top link assembly compresses and lowers the 3pt arms.

This process repeats itself however often required to maintain desired depth. If I have my plow adjusted properly, i.e., sitting flat laterally and level front to back, these automatic adjustments are barely felt. I plow all day and my depth basically stays the same. Plow pulls easy. Tractor maintains speed and traction. Life is good.

There are other implements that might benefit from Draft Control but none as effectively as the Moldboard Plow.

Also understand, a tractor without draft control cannot control the 3pt action with the same precision and smoothness. Without Draft it's left up to the operator to make those adjustments. Simply not possible.

I'm not talking about plowing your garden. I'm talking about plowing acres and acres for hours and hours.

 

[jeff9366]

So if you wanted to smooth out some ripples with a box blade would it be better to use or not use draft control? Or just do multiple passes?

"Ripples" are unlikely to provide enough draft resistance to trigger Draft Control hydraulic lift of the Box Blade.

A Box Blade full of heavy, moist dirt can trigger Draft Control hydraulic lift.

 

[Coyote machine]

I've used draft dozens if not hundreds of hours. My Kubota and Ford both have it. I've never used anything but mechanical draft. It's very easy to describe.

Older tractors (60s 70s) versions usually only had one control lever. A separate lever flipped the system into/out of draft mode. Later models use 2 levers. Let's talk about that method.

So if I want to use draft I place the normal use 3pt lever in the lowest position. Now I control the 3pt with the draft lever. Let's say I'm pulling a 3pt moldboard plow.

I determine the maximum depth I want to plow. I set the stop adjustment on the draft lever at that position. So everytime I drop the plow with the draft lever to the preset stopper, my plow will always plow at that maximum depth. How does it do that???

The top link assembly on the tractor is not rigid. It's usually mounted using a very strong spring. Somtimes using a compression system with a durable rubber bushing or some type of system that compresses and extends by the push/pull forces applied by the top link on my plow. Clear as mud right?

So I drop the plow with the draft lever to the stopper and start forward movement. The plow immediately heads for China (digs itself into the ground. This causes extension forces on the top link. The plow wants to go deeper. As this force increases it begins to extend the top link assembly on the tractor. As the mechanism extends it begins to move the controller inside the tractor toward the position of raising the 3pt. When the force is great enough lifting action stops the descending plow at the depth you previously determined. If the plow for whatever reason starts elevating above your preferred depth the top link assembly compresses and lowers the 3pt arms.

This process repeats itself however often required to maintain desired depth. If I have my plow adjusted properly, i.e., sitting flat laterally and level front to back, these automatic adjustments are barely felt. I plow all day and my depth basically stays the same. Plow pulls easy. Tractor maintains speed and traction. Life is good.

There are other implements that might benefit from Draft Control but none as effectively as the Moldboard Plow.

Also understand, a tractor without draft control cannot control the 3pt action with the same precision and smoothness. Without Draft it's left up to the operator to make those adjustments. Simply not possible.

I'm not talking about plowing your garden. I'm talking about plowing acres and acres for hours and hours.

Good explanation! Now for an average box blade trying to grade a gravel drive, would the use of draft make sense, from your POV, or is it just as easy or easier to operate the BB manually?
For instance I have 3 holes in the toplink bracket on the tractor. Which one would be best to accomplish the task. I also have top-n-tilt cylinders to raise the BB or adjust it's angle/tilt hydraulically.
Thanks for any further clarity you can bring to this subject.

 

[jeff9366]

The original purpose of Draft Control was to keep plows encountering underground obstructions from pivoting tractors on their rear axles into a vertical orientation.

I had this experience once, dragging logs behind a JD 750, when one of the logs stopped against an exposed root. Going from horizontal to vertical took less than one second. I was glad I had my seat belt secure.

Most new plows today have either a trip protective mech or shear bolt protection.

 

[MtnViewRanch]

Part of the problem with draft control is, well there is no problem. The only problem is that people do not understand how and where to make use of it. Most people think that it is a feature purely for plowing.

While that may very well be what it was originally designed for, by no means is it the only use for it. People think, oh it raises and lowers and that changes the out come of what I'm trying to do. Really? When a box blade or rear blade raises less that 1/8" that it changes your out come?

If you have large jumps happen, then most likely you have things set wrong for the existing conditions. I have had my draft control set so sensitive that it literally was going up-down no more than 1/16". It drove me nuts and have never set it that sensitive since. Seems to work quite well with my rear blade to where it will raise up about 1/8". I can move along making a cut for a new road in virgin ground and never get stopped. The blade raises just enough to let me continue on.

I will say that I'm sure that it is easier to make use of with a heavy tractor that has some power, but I have given people with 6-7000lb tractors instructions on how and what to do and they have all been grateful.

Number one thing, READ YOUR OWNERS MANUAL. Typically this should tell you how and what to do and then with a little experimentation you can apply that knowledge to whatever the ground engaging implement is that you want to use it with.

 

[ovrszd]

CM,

In regards to your top link bracket on your tractor with 3 holes. One end of this bracket is pinmed to the tractor
The other end is pinned to the compression/extension system I described earlier? The closer you pin your top link to the rigid pin the less sensitive the draft control will function allowing more vertical movement of the 3pt arms before action is taken. Closer you pin the top link to the compression/extension assembly the less vertical movement necessary for action.

Not judging your ability to run a BB, just saying. For me I'd not use the draft function. I'd control the BB with the normal 3pt lift lever/system.

I've actually never considered using Draft Control for that purpose. I'll try it next time I'm using the BB.

Give yours a try and report your results.

 

[ovrszd]

I was typing while Brian was typing. I consider him a master with his BB. If he says draft control improves BB function, I believe it

 

[Rustyiron]

Brian & Richard, for this post d/c = draft control
For plowing - say your in some nice topsoil and run into a section of hard clay, shale, what ever. The d/c raises up the hitch until the "resistance" (in the d/c) is the same as your setting in the nice topsoil. The plowing depth does change. What influences the d/c is the pressure on the top link at the tractor and that is a result of loading and the depth (of cut) is the "fix" right?

And Brian, I could see "roughing in" a new grade using d/c, but for finish grade?
I am not questioning you guy's at all, actually the opposite, but the above has been my thinking for a long time, it makes (mechanical) sence to me. But then, I was never really taught the proper use. Edgumcate me Thnx.