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.