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Thread: Trim motor

  1. #11

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    Default Re: Trim motor

    Quote Originally Posted by jiott View Post
    The black rod that moves up and down when you activate the motor is adjustable...
    This morning I disconnected the scissors link & the rod end and ran it to full up. I turned the inner shaft clockwise until the scissors link tab was down against the outer tube. I did this a dozen times. I attached the heim joint and adjusted to get my 7/16 inch clearance. I ran the stabilized full down, ran it up and it goes to no clearance.
    Full up stabilizer is nose down. I can't imagine ever needing that much up travel. You thoughts.

  2. #12
    Senior Member jiott's Avatar
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    Default Re: Trim motor

    This is incredible, I can't believe it! After you have made the adjustment and reconnected and locked the scissor links and rod end, there is no way the unit can extend farther. If it does, I give up; maybe there is something drastically wrong with the trim motor unit.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #13
    Senior Member jiott's Avatar
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    Default Re: Trim motor

    By the way what is a "heim" joint?
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  4. #14
    Senior Member Dave S's Avatar
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    Default Re: Trim motor

    Heim Joint is street rodder speak for rod end

    DS

  5. #15

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    Default Re: Trim motor

    Also the name of the company that makes them.

  6. #16
    Senior Member jtpitkin06's Avatar
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    Default Re: Trim motor

    I read this post a few times and tried to figure out what was so difficult. Then I went back and read the manual instructions. Yeah… clear as mud.

    OK, here’s the deal. In the final assembly instructions you are directed to check that the rod end is threaded all the way into the end of the actuator. If it is not, then you adjust it inward by disconnecting the scissor links (do not disconnect the rod end) and rotate the actuator rod counter clockwise.

    You are screwing the actuator upward onto the rod end. Why do it this way? Because it is much easier to take off the scissor link and rotate the actuator rod than it is to pull the rod end out of the stabilizer. This method keeps the stabilizer attached to the fuselage at all times.

    Then you are instructed to adjust the rod end by rotating the actuator clockwise. When you rotate the rod clockwise the ball screw turns inward and the assembly gets shorter. At the same time the rod end unscrews and the assembly gets longer. This is why the instructions say to reapply power to extend the actuator and recheck your measurement.

    Just to make the instructions simple let’s rewrite them here:


    Adjust the rod end to obtain 7/16 clearance between the top of the horizontal stabilizer leading edge and the fuselage directly above it with the trim actuator fully extended.

    Step 1. Make sure the rod end is screwed into the actuator all the way.
    Step 2. apply power to the actuator to fully extend the rod. You may use a 9 volt transistor radio battery as a power source.
    Step 3. Measure the vertical clearance at the leading edge of the stabilizer.
    Step 4. To make adjustments, disconnect the scissor link and rotate the actuator rod.
    Step 5. Apply power again to the actuator to fully extend the rod. Recheck the clearance. Repeat step 4 if needed.
    Step 6. reconnect the scissor links and install cotter pins.

    Step 7. Tighten the rod end lock nut and secure with Loc-tite

    You’re done!!!

    First, let’s make it clear that turning the actuator rod does not adjust any internal end points inside the ball screw actuator. If you screw it in manually it will still travel to full extension or retraction when operated electrically. The actuator will extend to the end of the stroke and then it simply recirculates the balls. You can manually run the screw full in and full out and the length of the electrical stroke does not change.Likewise you can fully retract the actuator electrically and it will reach the minimum extension where the balls recirculate.


    You can only change the total length of the mechanism by adjusting the rod end.

    If you adjust the rod end by rotating the actuator rod you temporarily change the ball screw total extension. No problem. Just run it electrically out to full extension and recheck your stabilizer clearance for the 7/16 measurement.

    Now if you have attempted to do the adjustment and your stabilizer is hitting the fuselage, it indicates you do not have your rod end screwed all the way in. It is also possible you are using a lock nut that is too thick preventing the rod end from screwing in the necessary amount.


    That’s all there is to it!!!
    John Pitkin
    Greenville, TX

  7. #17
    Senior Member jiott's Avatar
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    Default Re: Trim motor

    John's got it dialed. A much better explanation than I was trying to give.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  8. #18
    SWeidemann's Avatar
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    Default Re: Trim motor

    John,

    Looks like a well done set of instructions. I've prtinted them to take back to the hangar shop.

    Thanks much, Skot
    Kitfox Vixen 912 ULS
    N24V at C29

  9. #19
    Senior Member jrevens's Avatar
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    Default Re: Trim motor

    Thanks for that explanation, John... excellent!
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  10. #20

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    Oct 2008
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    Stillwater MN
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    Default Re: Trim motor

    Quote Originally Posted by jtpitkin06 View Post
    I read this post a few times and tried to figure out what was so difficult...
    John,
    Thanks for the reply. Many of your replies over the years have been a learning experience.
    My problem still exists. As a test I disconnected the rod end from the stabilizer but left the scissors link connected so the rod would not spin. I extended the rod full length.5 1/4 inches. I disconnected the scissors and turned the rod clockwise until it stopped. 1 1/4 inches now sticking out.
    Re installed the scissors link and extended the rod. It went right back to 5/14 inches. The same thing happens when I do the adjustment. Jim

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