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  • Help mee! Center bolt of Pulley loosen!!

    Discussion in 'The main mechanical design forum' started by anhlt7337, Sep 18, 2021.

    1. anhlt7337

      anhlt7337 Member

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      Hi everyone!
      Have a good day!

      I'm designing a transmission for scooter. But I have a problem.
      The center bolt to fix driver pulley was loosen after run test although it applied thread lock adhesive.
      Its wrong direction of thread or the bolt tightening torque not enough? anybody can help me to calculate how much axial force of center bolt is enough to fix driver pulley. Thanks so much!

      upload_2021-9-18_17-18-59.png
       
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    3. s.weinberg

      s.weinberg Well-Known Member EngineeringClicks Expert

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      Can you replace the single bolt with 2 that are off-center? That way the rotation of the pulley wouldn't be loosening your bolt in the same way
       
    4. Dana

      Dana Well-Known Member

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      Generally you need something positive to lock the shaft and pulley together rotationally, relying on an axial bolt clamping and friction isn't going to do it. A shaft key in a keyway is the standard method. A clamping hub (taper bushing) is another option. A setscrew from the side against a flat on the shaft is also commonly used, or sometimes a cross pin in a hold drilled through the pulley and shaft.
       
    5. anhlt7337

      anhlt7337 Member

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      Of cause, I use spline coupling instead of key shaft
       
    6. anhlt7337

      anhlt7337 Member

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      I know this concept, but it just suitable with chain driver. (prevent driver sprocket move out). But for belt driver, driver pulley have to fixed. So I have to tightening by center bolt. KTM or Zero motor also tight center bolt with high torque, so I want to know how to calculate torque of this bolt
       
    7. Dana

      Dana Well-Known Member

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      True, though a spline coupling will usually be more expensive to manufacture than a keyway.
       
    8. s.weinberg

      s.weinberg Well-Known Member EngineeringClicks Expert

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      I'm not sure I'm getting it.
      I don't know why you can't use two or more bolts.
      I especially don't understand why if you are using a spline for torque transfer, and the bolts just to handle whatever axial forces you need to hold the assembly together.
       

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