Power Loss With Bevel Gears

Discussion in 'Clock Construction' started by scootermcrad, Apr 18, 2020.

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  1. scootermcrad

    scootermcrad Registered User
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    Hey everyone,

    In my ongoing efforts to understand all things horological, I have been thinking about the use of bevel type gears (wheels) in large clocks. Especially tower/turret clocks. It seems the use of bevel gears for fly fan governors is not as popular in US makes, but very popular in European makes to put the fly fans above the clock (horizontal rotation) instead of the back or front of the clocks (vertical rotation).

    Does anyone have information they can share on power loss through bevel gears/wheels with cycloidal type teeth? There are some high level documents out there on power loss with involute style bevel gears, (they read like stereo instructions) but I haven't found much of anything on cycloidal types.

    My end goal is to learn about power losses through the use of bevel gears/wheels to place fly fans above the clock movement and the additional weight that could be needed to address power losses in these configurations. Maybe these are completely negligible losses, but it seems there is some theory about loss in these types of components.

    Any help would be appreciated!

    Thank you!
    Scott
     
  2. scootermcrad

    scootermcrad Registered User
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    I'm seriously open to any theories and discussions here. I'm thinking on a larger scale (weight driven clock), the power losses would be negligible, as apposed to a smaller skeleton clock, but maybe even then the effects would be small.

    No way I've stumped the board with this question. HAHA :)
     
  3. gmorse

    gmorse Registered User
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    Hi Scott,

    Since the purpose of the fly is to dissipate excess energy, surely the power absorbed through gearing and that through air resistance both contribute to the desired result?

    Regards,

    Graham
     
  4. scootermcrad

    scootermcrad Registered User
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    That is a good point. And assuming that there won't ever be a situation where you wouldn't want SOME kind of rotational resistance from the fly, it may help the equation a bit.

    Thank you for the input!
     
  5. Jim DuBois

    Jim DuBois Registered User
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    Properly sized and executed bevel gears consume no more power than other versions of gear trains.
     
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  6. scootermcrad

    scootermcrad Registered User
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    Thanks Jim! I don't have much experience using bevel gears. It seems that would be the case as long as the geometry was properly cut into each gear.

    Is it also a true statement that cycloidal bevel gears must be two different sizes in order for there not to be binding. I'm trying to process that statement as well. Again, it seems if the geometry is the machined correctly, it wouldn't be an issue, but maybe I'm missing some basic info, here.
     
  7. Jerry Kieffer

    Jerry Kieffer Registered User
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    While I can certainly discuss the issues, it is not practical because of the amount of material that may need to be covered on a forum such as this. My suggestion would be to contact customer service at a gear manufacturing company such as Boston gear.
    Open Gearing Products | Stock Gears, Modified Gears, & Custom Gears | Boston Gear

    At this point, request a catalog that contains the pros and cons of the various types of bevel gearing as well as functional specifications. From this you will be able to select what you wish and determine if it is best to purchase gearing or machine your own.

    Good Luck
    Jerry Kieffer
     
  8. scootermcrad

    scootermcrad Registered User
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    Thanks Jerry! I appreciate that response. Good idea.

    I've seen discussions of power loss with involute style profiles in bevel gears, but cycloidal profiled bevels for horological applications have little to no information available. Engagement seems to be different between the two styles, thus different loss characteristics. But, I've also never really designed around ANY type of bevel gear.

    Thanks again for any discussion!
     

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