I just bought a Case 105A upgraded from a Kubota that did not have this. In the operators manual it mentioned 2 settings. One is where you push the position lever all the way forward and set the implement depth with the draft control lever. The other is where you set the position of the implement with the position lever and then you move the draft control lever to match the position lever. Basically seems like you get the same results ? It does not say much else.
I will be pulling a 3 point plow and I am wondering what is the difference between the two settings?
I understand that the basic function of draft control is to keep the plow from digging deeper while plowing but I’m not sure how to set the levers for when I am using the plow with draft control.
Here’s how it worked on my IH2500b. That used a rock shaft to detect load. Other machines use different methods. But the goal is the same: if the tractor load starts to increase, draft control raises the plow (or whatever implement) out of the ground to decrease the load. As the load returns to normal, the draft control lowers the plow further into the soil, up to the depth that your position control was set to, and no deeper.
How draft control works, as explained on my old IH2500b...
There's a triangle formed by three sides:
1- the line of the back of your tractor
2- the line of your lift arms to implement
3- the line of your top link
There's a rock shaft somewhere at the point that your top link connects to your tractor.
Now, let's say you're driving along with a plow in the dirt. You're in soft easy soil, and all of a sudden you come into some harder soil. Your plow has a harder time cutting through the soil, putting drag on the tractor, so the rear wheels start spinning instead of pulling forward.
As the rear wheels spin, they start digging a hole, which lowers the rear of the tractor.
When the rear of the tractor lowers, the implement does not, because it floats.
Since the rear goes down and the implement does not, that puts pressure on your top link. The top link is trying to get shorter but it's solid. It has to maintain the three legs of the triangle. The implement pushes the top link against the rock shaft. The rock shaft activates the 3 point hitch to lift the implement out of the ground. It keeps lifting until the plow comes out of the ground enough to allow the rear tractor tires to stop digging a hole and start moving forward enough to allow the pressure on the rock shaft to diminish and it lowers the plow back into the ground, eventually back to the pre-determined depth that your position control was set at, unless it hits hard dirt again.
The plow causes a constant push and relax on the top link, depending on soil conditions.
You can manually set the sensitivity of the draft control to react faster or slower to conditions.
So, to summarize:
Draft control keeps your tractor from burying the rear tires by raising and lowering the implement as soil conditions change.
Position control allows the implement to drop to a preset depth and no more.