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NCTIM, Draft control and position control are two separate systems that work with the 3-point. The Ford-Ferguson 9N and 2N as well as the TO-20, TE-20 series and possibly the TO-30 & TO-35 only had the draft control. Here is basically what they are. Draft control: Maintains a constant drag force on the tractor for soil engaging implements.. i.e. plows. This keeps the tractor pulling with the same amount of force as you proceed through the field. How it works: When a plow is in the soil the tractor pulls it forward on the two lower points of the lift. To keep the plow from rotating on that axis the top link is there. Thus, there is a forward force on the top link. As the soil gets thicker and the implement is harder to pull the force on the top link increases. When the force gets high enough to compress that big spring under the seat the rod going through the spring actuated the hydraulic pump to raise the implement. As the implement is raised the force drops back to the desired level. This was Harry’s brilliant engineering addition to the industry. All his systems have this. Position Control: Maintains a implements height (or Position) off the ground. i.e. a mower. The fingertip control sets the height of the implement, however, it is very hard to set the controller at a truly neutral position… i.e. where the lift is not continuing to raise or fall just a little. This movement may be less than ½ an inch a minute. But if you are mowing, then this little movement can give you varying grass cut heights over a couple of hour job. Thus, the need for position control. How it works: The easiest position con troll is to hard link the implement to the tractor. i.e. limiter chains. This has the obvious draw back of being limited in height selection and difficult to set/reset. The other method is a hydraulic feed back loop in the control system. This method links the lift arm rotation to the fingertip control lever. Thus, as the lift drops, the lift arms rotate down and the feedback linkage pulls the fingertip control lever back commanding the lift to rise. As the lift rises the lift arms rotate up and push the fingertip control lever forward, commanding the lift to lower. As you can see, this system is constantly commanding the lift to return to the originally set position… thus position control. Now there are at least three current methods to add position control to your tractor. There are two commercial products for around $80.00 and a make at home plan that you could do for around $10. They all work about the same and all are effective. If you want the plans for the make at home I can send them to you if you leave an e-mail address. Respectfully Jeff
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