Draft control, commonly referred to as the cheater control. It is used on implements that are hooked to the three point hitch and operate below the ground surface, like moldboard plows, mounted field cultivators and chisel plows. When using the draft control, you adjust the depth of the implement using the draft control lever. Once you get it set the depth you want to operate, you then adjust the speed that the hitch responds to a change in the draft (how hard implement is to pull). You do this with the position control lever by moving the position control lever down into the very lower offset section of the quadrant. There is an off set on quadrant that , if levers are properly adjusted (which very few are now days with everybody and his brother working on the tractors) the farther you go into that action control, (speed of raise control) the slower the hitch will respond to a change in load. It does this by bypassing a portion of the oil from pump when hitch calls for a raise of hitch.
You attempt to adjust the action control so that the engine maintains constant RPM's. In other words, when you hit a tough spot, the hitch raises some to reduce the pull on the tractor. If you set it too fast, the hitch will be constantly adjusting and jerking up and down. Too slow and engine will start to pull down.
It works good on uneven ground where the front end of tractor goes up and down over the terrain a lot. On those occasions, the draft control will actually keep a much evener depth of implement than a set point using positon control. On flat ground, with varying soil conditions, the raising and lowering of the hitch will cause uneven depth. That is why very few ever use draft control in this part of the country.
For normal three point work you put the draft control ALL the way forward so it is locked out. I always felt and still do that it should be an option on three point hitch. If you left out all those torsion bars and internal linkages a customer would have a lot less problems especially when tractor ages. The new tractors use a electronic lower hitch pin that is very expensive and trouble some. After market mfgs come up with by pass kits and plain old pins to replace them. I think that would be an option mfgs would offer.