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  1. #1
    RC poster
    Join Date
    Feb 2018
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    13

    UDR gear rations

    Interesting about gear rations and as a comment points out....
    "I think if you guys had turned the motor, you'll find for every turn of the motor, you'll get more turns from the rear than the front. The rear axel is 1:1 discounting the differential, the front is 2:1"


    https://youtu.be/iwqqko5cjBk

  2. #2
    RC Competitor
    Join Date
    Aug 2017
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    52
    No correct. He keeps the other front wheel still while turning the other, and that makes the difference. If he'd turn both front wheels TOGETHER one turn, also rear wheels go around one turn.

    They just don't understand what they do - so false information.

  3. #3
    RC Racer
    Join Date
    Feb 2017
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    200
    Quote Originally Posted by BPee View Post
    No correct. He keeps the other front wheel still while turning the other, and that makes the difference. If he'd turn both front wheels TOGETHER one turn, also rear wheels go around one turn.

    They just don't understand what they do - so false information.
    Yeah, I tried that at my hobbystore today on their display unit and you’re correct. I spun the driveshaft and the result was the same as when I spun either both fronts or both rear wheels: equal revolutions. Only if you hold one front wheel like in the video you can re-create this.....


    Sent from my iPhone using Tapatalk

  4. #4
    RC Qualifier MAC FAB's Avatar
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    Apr 2014
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    Can someone explain the physics of why it speeds up when a wheel is held? The gearing hasn't changed, so please enlighten me as to how that can happen? Over my head.

  5. #5
    RC Competitor
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    Aug 2017
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    https://youtu.be/F40ZBDAG8-o

    Starting at 3:33. THE moment lasts only about ten sec, but if you watch it carefully - you’ll understand.

  6. #6
    RC Racer cozyFozy's Avatar
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    Oct 2017
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    Quote Originally Posted by BPee View Post
    https://youtu.be/F40ZBDAG8-o

    Starting at 3:33. THE moment lasts only about ten sec, but if you watch it carefully - you’ll understand.


    That's a great visualization for teaching,
    I just had a short rant on another thread about the same video the original poster asked about here. I didn't realize you guys were discussing this over here. I think they (the two guys in the video) may have just forgot/didn't notice that the rear axle has the same set of planetary reduction gears that is in front of the center diff. Front and rear wheels spin equally, not 2:1 front/rear.

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