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Vehicle Instantaneous Torque in initial motion

  1. Oct 18, 2013 #1
    I'm designing a propulsion system for an electric car as a part of a college project. I'm trying to find the minimum torque needed so the car can begin to move, i'm assuming this will be the greatest torque required for motor selection, provided the vehicle will accelerate relatively constantly and then maintain a constant velocity.
    There will be direct transmission so the only loading I can think of in the car is the static bearing loading that must be overcome. Assuming I know the acceleration of the vehicle, How would I find this torque?
    Thanks for any help..
  2. jcsd
  3. Oct 18, 2013 #2


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    Science Advisor

    The torque will have to initially overcome the total static friction. That has not been specified.

    Can you measure the starting force needed with a spring balance?

    If you put a vibrator or an unbalanced smaller motor on the vehicle you will be able to rock it sufficiently to change the static to the lower dynamic friction.
  4. Oct 19, 2013 #3
    I'm actually making a model of the proposed car to maximise fuel efficiency (km/kWh) so there's no way of doing any physical tension.
    I was under the impression that the total static friction was the maximum torque that could be applied to the car without it the wheels slipping?
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