Re: What is Draft Control

Posted by Salmoneye on January 16, 2002 at 05:40:52 from (207.40.137.11):

In Reply to: What is Draft Control posted by Wayne on January 16, 2002 at 04:31:31:

I stole this from the Ford N Board and it was written by 'Larry'.

This explanation refers to Ford N's specifically, but also explains in general terms the way that Draft (Draught) and Position control work on a 3-point lift...

"Position control and draft control are meant to do two entirely different functions. Thus they have two entirely different ways in which they act in response to the touch control lever. Position control, obviously, is meant to hold an implement at a fixed height above the ground anywhere within the lift range from full up to full down. And the height is proportional to the position of the touch control lever - lever full up, implement full up; lever one third down, implement one third down; and so forth.

Where as draft control is meant to hold the amount of draft (pulling load) or drag. The draft is a function of the depth of a plow, as well as soil type. The same proportionality as in position control - full down, maximum pulling load; half up, half the pulling load as full, and so forth. BUT you can not easily move from one field to another with an implement in the ground. SO the last little bit of the touch control range at the top is used to tell the hydraulics to lift the implement to transport position. Since there is no need for a plow to go up only part way, say six inches off the ground, the lift is raised fully for transport position.

To tell where the transition point between transport and draft is on the touch control lever, carefully move the control lever, from full up, down very slowly, until you reach the point where the implement starts to slowly drop. This is the lightest, or shallowest, draft setting you can achieve. Raising the touch control lever any higher will activate transport mode. When you drive forward the hydraulic system will continually adjust itself to maintain the draft setting you have made. Then as you move the control lever father down you are setting a higher draft. Thus the draft will be harder or the plow depth deeper. You can set the drag so high that the N will either stall or slip the wheels. Or at least that is true with my unweighted rear wheels.

This is the genius of Fregusen's design. If you hit hard soil you do NOT have to readjust the implement height to keep from stalling or spinning the wheels. Until Ferguson's hydraulic control design came along, maintaining a constant depth, consistent with the pulling ability of the tractor was a constant fight for the farmer. In uneven ground, varying soil conditions, meant the farmer had to readjust the plow as he went along, NOT an easy task, especially when many plows of the time were manually adjusted.

I almost always use draft control when I am grading. I find I can control the amount I am "digging in" much easier that way. You can also pickup a "set" amount of material and pull it as far as you need to. In the case of snow, since it is relatively light compared to other "loads" that the blade might work, you probably need to use the very lightest draft setting you can get by with.

Also remember, if you are not moving then there is no pressure on the top link and thus on the internal control mechanism, so the lift will fall all the way down. Then when you start to move the internal control mechanism will sense the load and adjust. But the first few feet you may not have happening what you want. :-) I generally try to have the blade up when stopped and then lower it as I am moving. I have better control that way. You will just have to practice to get good."

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