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  • Gearing down & High torque

    Discussion in 'The main mechanical design forum' started by pierroil, Jul 18, 2011.

    1. pierroil

      pierroil Member

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      I need to achieve a a very low RPM (0.01) and I have a servo motor (BSM60 from Aerotech) motor that can go down to 1 RPM.

      So I just need a speed reducer that will be able to bring it down 100 times more.

      I'm looking at products from SDP-si (the only company i'm allowed to use) but i'm totally confused!

      The problem is torque : I need high torque / my motor is going to produce a hell of a lot of torque (given the power = torque * velocity equation and the fact that i'm moving at such a sow rate)

      Can someone please help me find a product from SDP-si (sdp-si.com) that can actually take this load! 90 degree angle drive, or striagh drive, it all doesn't matter, so long as the product won't break.

      I was looking at their speed reducers, but they only do a maximum of 4 N.m which means they will break when I give them a slow moving motor...

      Thanks a lot for your time!

      PS : Example of my dilemna : 100 speed reduction but only 1.97 N.M? So does that mean if I pucnh in a slow moving BSM motor (with high torque) it will break?!
      https://sdp-si.com/eStore/Direct.asp?GroupID=790
       
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    3. michmichyo

      michmichyo Member

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      First of all, keep your head cool to solve any problem like this.

      You have to be careful of splitting in your mind what are your inputs and what are your outputs of the "speed reducer".

      Clearly, you have your motor as an input and another system as an output.
      The torque should be greater at the output as the speed has lowered.

      If you need more that 4N.m to have the output rotate (for your example) so then yes, you will have a risk of failure.
      Another thing is the safety coefficient. If you need 4 or 3.5 N.m to have your output rotate, don't choose the speed reducer limited to 4N.m any case !! According to the system/norms, choose the right safety coeff: is you need two for example and the limitation of the reducer is 4N.m, ensure you need no more than 2N.m to have your system rotate.

      To design a system, think in terms of output and inputs.
       
    4. maniacal_engineer

      maniacal_engineer Well-Known Member

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      I had a similar problem when designing an infinitely variable transmission that could go down to zero - the output would theoretically go to infinite torque. I resolved it by making soem assumptions about the maximum load that could be generated (based on traction etc) and sizing components based on that. I would figure out the maximum load, add a factor of safety, and then use a torque limiting clutch as a fuse to protect the gearbox from itself.
       
    5. pierroil

      pierroil Member

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      Thx all
      (Thanks a lot to the first replier which I subequently msged) finally just decided to use a Art310 from aerotech. Should be enough, and if not, i'll use a belt drive and pulleys to finish off my reduction!

      Thanks
       

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