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  • what gear ratio to use?

    Discussion in 'The main mechanical design forum' started by jawnn, Jun 22, 2015.

    1. jawnn

      jawnn Well-Known Member

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      [FONT=Lucida Grande, Trebuchet MS, Verdana, Helvetica, Arial, sans-serif]I really do not know how to think abou this, I want to know ratio I should use for a single gear on a specific hill[/FONT]

      [FONT=Lucida Grande, Trebuchet MS, Verdana, Helvetica, Arial, sans-serif]I am wanting to use no more than 2 brake horse power at the axle. for a moped velomobile. I understand that most people just don't even thinnk abou tthese things, and just use all the power they need to climb a hill.[/FONT]

      I used this calculator on the 'streamlined trike' setting. I assume that it is taking into account a two stage gear reduction loss of 15%. http://www.kreuzotter.de/english/espeed.htm

      The motor I want to use produces 1500 rpm at 1500 watts [on 7% grade with 400lbs it should produce 22.2 mph]

      Ie: 3â€pulley on motor/12â€rim pulley on drive wheel= 4:1; 1500rpm/4 =375 rpm

      20†tire with a 12†rim pulley on the 20†drive wheel and 3†pulley on the motor (1:4 ratio) with 1500 rpm motor (at 1500 watts or 2 HP would give you about 22.3mph.

      4â€/12â€= 3:1....1500rpm/3 = 500rpm = 29.73mph minus 20% = 23.78 mph? Is that close enough to keep the motor from over heating on that same 7% grade?

      this is the motor:
      http://www.cloudelectric.com/product-p/mo-me0909.htm
       
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    3. jawnn

      jawnn Well-Known Member

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      [FONT=&quot]Notknowing how to think about this concept, I am contemplating how some motors useexponentially larger amounts of power to just to double the speed. So will thatmean that at 1500 watts the vehicle would slow down on the given hill, than Icalculated?[/FONT]
      [FONT=&quot] [/FONT]
      [FONT=&quot]And ifthe Elf pedal-car can climb the hills that they claim, it is definitely notlimited to the one HP the motor is rated at. And they use a 1:1 gear ratio![/FONT]
      [FONT=&quot] [/FONT]
      [FONT=&quot]Thismotor is rated at 1.6 HP (1193.6 watts) so the top cruising speed should begeared to about 21.6mpg for near to sea level....on a 5.6% grade. What withthat being 20% less than the 7% grade I want to climb. Or do I need tocalculate an exponentially smaller grade?? if so, HOW?[/FONT]
      [FONT=&quot] [/FONT]
      [FONT=&quot]And ifyou understand that can you tell me if this motor is this a compoundseries/shunt motor?

      Is this understandable at all?[/FONT]
       

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