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  1. #1
    Elite Member JasG's Avatar
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    Default old model 4020 draft control question

    Today I helped a friend replace the seals on the draft control shaft on his old model 4020. In order to get the shaft back in through the notch in the draft control arm we had to play around with the level on the side of the rockshaft control. This lever has 3 positions, it was always in the middle position, to get the draft control arm free we had to move it to the bottom postion.

    Now the arms will only lift with that lever in the bottom position and only lift part way.

    Any ideas what went wrong or how I can correct the situation? I'm not sure what that lever is. The dealer I picked up the parts, they said I might have to play with it to get the shaft back in. Until I move that lever there was pressure on the arm and the shaft wouldn't line up with the holes on the other side.

    It is also possible the hitch was set up due to my friend doesn't use the hitch that much. Had a hard time getting the hitch to drop when I started.
    “Government is like a baby. An alimentary canal with a big appetite at one end and no sense of responsibility at the other."


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  2. #2
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    Default Re: old model 4020 draft control question

    That lever is for draft sensing. The three positions are "L" for load control, "D" for depth control, and "LD" for combination of load and depth control. "L" should be used when moldboard plowing so if the ground gets too hard and it tries to make the tractor spin out, the load shaft flexes and moves the linkage to raise the plow automatically until through the hard spot. "D" should be used for most general three point work such as rotary mower or scraper blade. "LD" can be used for light tillage, such as maybe a chisel plow.

    Now for your problem. With the lever in "D"(bottom position), try shortening the cable from the lift lever to the lever going into the control valve. You need to remove the sheet metal from the right side of the rockshaft housing to get to the adjustment. You should be able to shorten it enough to get the hitch to raise all the way. If not, either the cable is bad or some of the internal linkage could have become displaced while you were trying to get the load shaft back in. Did you have the three point arms all the way down when you removed the shaft? If not, the likelihood of displacing linkage is much higher. If this happens, the rockshaft valve housing needs to be removed to repair.

  3. #3
    Elite Member Tx Jim's Avatar
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    Default Re: old model 4020 draft control question

    If parts key #8 gets out of rockshaft control linkage is what JD110 was referring to(displacing linkage) but usually rockshaft won't raise any when this happens. If adjusting cable doesn't help then place rockshaft control lever on dash on the "1" with small lever in "D" and remove bung in rear of trans. With engine running insert a ""taped on an extension"" 9/16 socket,push in on spring loaded lock(parts key #4) and turn nut(parts key #1) until rockshaft just starts to raise.
    Attached Thumbnails Attached Thumbnails old model 4020 draft control question-rxa0051164_____un25jan01.gif  

  4. #4
    Elite Member JasG's Avatar
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    Default Re: old model 4020 draft control question

    Thanks for the advice, I will give it a try sometime in the next day or 2.

    When I started the rockshaft was all the way up. It wasn't till I had the shaft out that I had realized what was there.

    This repair started out as to repair a leaking seal around his PTO. Been leaking for a month or so. Then he told me he went from a very slow not even able to notice other than the PTO area wet leak to a gallon a day. Went up and found the draft seal on 1 side dripping badly. I had already set it up with the service department to replace the seals and and other worn parts on that.

    They told me this was an easy job if you know how to install seals.
    “Government is like a baby. An alimentary canal with a big appetite at one end and no sense of responsibility at the other."


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  5. #5
    Elite Member JasG's Avatar
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    Default Re: old model 4020 draft control question

    Quote Originally Posted by Tx Jim View Post
    If parts key #8 gets out of rockshaft control linkage is what JD110 was referring to(displacing linkage) but usually rockshaft won't raise any when this happens. If adjusting cable doesn't help then place rockshaft control lever on dash on the "1" with small lever in "D" and remove bung in rear of trans. With engine running insert a ""taped on an extension"" 9/16 socket,push in on spring loaded lock(parts key #4) and turn nut(parts key #1) until rockshaft just starts to raise.
    I hope to get to this over the weekend. When you say bung do you mean the threaded plug that is about 1 1/4 dia that needs a 1/2 drive ratchet to remove. this would be to the right and a little below the rockshaft valve housing?

    I'll try the linkage 1st then go after the adjustment.
    “Government is like a baby. An alimentary canal with a big appetite at one end and no sense of responsibility at the other."


    Ronald Reagan

  6. #6
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    Default Re: old model 4020 draft control question

    Quote Originally Posted by JasG View Post
    I hope to get to this over the weekend. When you say bung do you mean the threaded plug that is about 1 1/4 dia that needs a 1/2 drive ratchet to remove. this would be to the right and a little below the rockshaft valve housing?

    I'll try the linkage 1st then go after the adjustment.
    That is the correct plug. I don't want to confuse the issue, but I believe Tx Jim is mistaken on the position of the small lever. I think you need to be in "L" when adjusting the "load control extension". When in "L" and rockshaft is not raised, turn the 9/16" nut counter-clockwise until hitch just starts to raise. Just be sure to adjust the cable first, or the load control adjustment won't be accurate.

  7. #7
    Elite Member JasG's Avatar
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    Default Re: old model 4020 draft control question

    Quote Originally Posted by jd110 View Post
    That is the correct plug. I don't want to confuse the issue, but I believe Tx Jim is mistaken on the position of the small lever. I think you need to be in "L" when adjusting the "load control extension". When in "L" and rockshaft is not raised, turn the 9/16" nut counter-clockwise until hitch just starts to raise. Just be sure to adjust the cable first, or the load control adjustment won't be accurate.
    Thank you.
    “Government is like a baby. An alimentary canal with a big appetite at one end and no sense of responsibility at the other."


    Ronald Reagan

  8. #8
    Elite Member Tx Jim's Avatar
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    Default Re: old model 4020 draft control question

    Yes JD110 corrected my "Oldtimers" mistake. The only correct way to adjust the load & depth mechanism is following a JD service manual and start at the beginning and adjust item by item.

  9. #9
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    Default Re: old model 4020 draft control question

    I am about to change my draft control seals so thanks for all your advice. My lift is slow and drifty in the D position. It raises some, but I have to finish raising equipment with the L/D lever in L/D position. Will the adjustment on the back of the rockshaft fix this problem or should I look at the cable adjustment?

  10. #10
    Elite Member Tx Jim's Avatar
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    Default Re: old model 4020 draft control question

    jed4570
    To correctly adjust the L/D control mechanisms one needs to follow the instruction in a service manual. There are several adjustment steps that must be performed or checked for correctness.

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