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  • Timing belt damage issue

    Discussion in 'The main mechanical design forum' started by kevin136, Nov 19, 2011.

    1. kevin136

      kevin136 Well-Known Member

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      Hey guys,
      There is a problem about timing belt of a drive mechanism.The tooth have been damaged completely during the life test with full load.I check the pulley dimension,center distance and the strength of belt,are all ok.
      Does someone have any idea about that?
      Thanks a lot!
      kevin
       
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    3. PeterC1972

      PeterC1972 New Member

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      Are the drive and driven shafts parallel? If there is a slight angle between them, the belt will walk one direction of the other; either motion puts a twist on the belt. I had a water pump on an auto that was manufactured incorrectly. By the time I drove home from the shop (5 km), the belt was completely off of the pulleys.
       
    4. kevin136

      kevin136 Well-Known Member

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      Hello Peter,
      Thanks for your attention!
      According to the drawing tolerance and the way of assembling,I think there is no problem about parallel.Indeed,a slight non-parallel axis may cause badly damage!
      Recently I disassembled the machine and found the tooth of driven pulley (small one) was badly abraded.The material of the pulley is Aluminum 6061.May be it's not strength enough to with stand the heavy load and high speed? Not sure,I want to do some comparable test.
      So the way I see it,after abrading,the pulley and belt are not meshed well,then damage the belt tooth.
      Do you have any comment on that?

      Kevin
       
    5. Dana

      Dana Well-Known Member

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      Belts wearing aluminum pulleys can be a problem, which is why aluminum pulleys are usually hard anodized to increase the surface hardness. But if it's "badly abraded"... is there contamination? Also if (you don't say) the load or power supply is not smooth (for example an IC engine rather than an electric motor) the peak loads may be much higher than the average load.
       
    6. kevin136

      kevin136 Well-Known Member

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      Hi Dana,
      Sorry I didn't clarify the initial condition.The drive structure works in a closed space,so that shouldn't be some wearing contamination.
      we use EC motor and stirrer a kind of liquid with certain viscosity.
      Anodized,maybe I can have a try.
      Thank you for your helpful info.

      Kevin
       
    7. vic.blackall

      vic.blackall Well-Known Member

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      Is the smaller pulley too small for the drive, you may need to increase the size of both pulleys to maintain the ratio.
       
    8. kevin136

      kevin136 Well-Known Member

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      Hello Dude,
      What do you mean " to increase the size of both pulleys to maintain the ratio"? Would you please explain it more details?
      thanks a lot!
       
    9. kevin136

      kevin136 Well-Known Member

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      to increate the diameter of the pulley?
       
    10. vic.blackall

      vic.blackall Well-Known Member

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      If the smaller pulley is being damaged because you are trying to transmit too much power through too few teeth then you need to increase the number of teeth on the smaller pulley and therefore increase proportionally the number on the larger pulley to maintain the same ratio, (if the ratio is important). If the smaller pulley has 15teeth and the larger pulley has 30teeth and you change the number on the smaller pulley to say 25t then you will need to change the number of teeth on the larger pulley to 50t.
       
    11. vic.blackall

      vic.blackall Well-Known Member

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      If it is not possible to change the size of the smaller pulley I would suggest that you change the smaller pulley material to steel, not anodized alum.
       

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