Rockshaft control

Discussion in 'John Deere' started by altontractor, Nov 11, 2009.

  1. altontractor

    altontractor New Member

    14
    Nov 11, 2009
    I'm new to the JD 790 having used a 1957 IH Utility 350 for the last decade, so ...

    I just removed the model 7 backhoe and cannot get the rockshaft upper link arms to rotate downward. Any suggestions on what I've missed here?
     

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  2. Hoyte_Clagwell

    Hoyte_Clagwell New Member

    24
    May 24, 2007
    The 790 has a knob under the seat that adjusts the rate of drop for the 3 point. It may be turned to where the lift is locked. I use this feature when sharpening my finishing mower blades. I put saw horses under the mower and then turn that knob to keep 3 point from leaking down.
     

  3. altontractor

    altontractor New Member

    14
    Nov 11, 2009
    I've cycled that knob through its entire range and there is no change. Thanks for responding.
     
  4. Live Oak

    Live Oak New Member

    Dec 21, 2003
    Should be a lever on the right side of the operators seat that goes up and down with numbers along the slot the lever moves in. I take it you have tried moving this lever and the rockshaft has not responded?
     
  5. altontractor

    altontractor New Member

    14
    Nov 11, 2009
    I have moved this lever ... a lot. The linkage to the hydraulic unit moves in conjunction with the lever, so it isn't broken.
     
  6. Live Oak

    Live Oak New Member

    Dec 21, 2003
    Have you tried applying some strong downward pressure on the lift arms with the rockshaft control lever in the full down position? It may just be a matter of the lift arms being stuck in the up position due to a long period of none use and the fact that the rock shaft links and arms are not installed which normally place enough downward pressure to pull the hyd. lift arms down.

    Keep in mind that the rockshaft hyd. lift arms are a ONE WAY servo. They only have hyd. power in the UP direction. Gravity and weight pull them down.

    You might try installing the rock shafts and lift links and try standing on the rock shaft for added weight to pull the hyd. lift arms down. As already mentioned, be sure the rock shaft drop rate valve under the operators seat is open to allow the rock shaft to drop down.
     
  7. altontractor

    altontractor New Member

    14
    Nov 11, 2009
    When all else fails, apply a lot of judicious force. So, I put the rockshaft control lever fully down, speed control to fast and then stood on top of it and hopped a little. 2 things happened - kids laughed, lift arms lowered. Everyone happy.
     
  8. Live Oak

    Live Oak New Member

    Dec 21, 2003
    Glad things worked out. My kids laugh at me a lot too....... at least until what told them proves out true. :D ;)
     
  9. MFreund

    MFreund New Member

    332
    May 1, 2008
    I was imaganing a video for America's Funniest Videos. Glad it all worked out!!
     
  10. Live Oak

    Live Oak New Member

    Dec 21, 2003
    Same thing happened to me yesterday. I got the tractor out of the shop to remove the MMM and install the FEL and the rock shafts would not go down.

    They would go down VERY slowly, about 6 inches in 15 minutes. Even with the bush hog on the back, it would not go down proper.

    I had not messed with the drop rate valve under the seat but somehow it got turn back to almost shut. Brain fart on my part. :clown: :kookoo:

    I forgot about the drop valve at first so I came back inside and re-read this post, adjusted the drop valve and all was well.