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  • Worm gears disengagement

    Discussion in 'The main mechanical design forum' started by Cardboard, Mar 26, 2010.

    1. Cardboard

      Cardboard Guest

      Ok so worm gears can only transmit drive they cannot receive from the cog correct...
      They are somewhat hard to disengage and reengage continuously so how would you recommend disengaging drive so that you can turn an axel freely when you want to and then engage the worm gear when you want to power the axle

      imagine a drive shaft coming off each side of this cog
      http://img.photobucket.com/albums/v280/ ... RMMOA1.jpg

      thanks
       
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    3. NPuglisi

      NPuglisi New Member

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      The few worm gears that I used to deal with in a factory were custom fitted to the gear they were driving, so they created matching wear patterns between the worm and the driven gear. That means if they were disengaged they needed to be engaged at the same location, and when we replaced one of them we replaced both. I don't know if your app needs that type of tolerance though.

      I have a few questions.
      What are the tolerances of the gears?
      What is the rpm range for the worm gear?
      Do you want the axle spinning in one direction only?

      I was thinking if you put some sort of clutch between the power source and the worm gear, you could release the clutch when you need to spin free, and engage the clutch when you need power.

      What's the application?
       
    4. Cardboard

      Cardboard Guest

      it is spinning at around 400 rpm and the axel needs to spin at around 40 rpm, the torque transmitted to the wheels needs to be around 100Nm, the wheel diameter can be between 50 to 150mm and there will be two wheels. the axel wont be more than 200mm long.
      the gears have not been specified yet so there is lots of play surrounding these.
      some sort of simple mechanism between the axel and the gear would be the simplest solution i think? but i cant think how to implement one. it can be too complicated tho some sort of lockable bearing that runs on the inside of the driven gear???

      [​IMG]
       
    5. Cardboard

      Cardboard Guest

    6. mvalenti

      mvalenti Well-Known Member

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      can you leave the gears in place and disengage the shaft with a clutch?
       
    7. Cardboard

      Cardboard Guest

      where would i clutch it? and how would i actuate it?
       
    8. maniacal_engineer

      maniacal_engineer Well-Known Member

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      You might be able to fit a dog clutch beside the worm wheel. The two wheels would be on a common live axle and the worm wheel would be separately rotating on the same axis, and could have holes in the side that would be engaged by the dog clutch, which would be splined to the wheels. the force to hold it in is small - essentially zero. you cannot continuously engage though. I am not sure how you would actuate it. Do you just need over-running? Then you could us a sprague / needle bearing type over-running clutch.
       
    9. Cardboard

      Cardboard Guest

      http://i108.photobucket.com/albums/n22/ ... 220016.png


      thats what i have at the moment, this wont allow over run but will allow the unit to be moved forwards while the worm is engaged.

      i get what you mean about a dog clutch actually and it could be quite simply done i think. it would have to be actuated by hand but it doesnt need to be sprung heavily as when it is engaged it has no reason to jump out. i just need to think about how you would move it along the axel engaging and disengaging it.
       
    10. SunilG

      SunilG New Member

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      I had sent you the solution. Was it of any help? Did not receive any feedback, so I was wondering if you had doubts about the suggestion.
       
    11. Cardboard

      Cardboard Guest

      sorry i was on holiday but pm sent
       

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