Aug 122012

Question by Mother G: I’m working on a “toy” car for 8th grade science (physics) What gear ratio would be the most ideal?
I tried 5:1, 25:1, 75:1 and others. NOW I JUST WANT SOME DAMN HELP SO I CAN GET A GOOD GRADE ON THIS PROJECT lol. okay…how does she expect us to learn what ratio works when there are like 400,000,000 to try. It would be nice if someone could just tell me what’s best for a ratio and why, isnt that all that really matters. I mean gosh…

Best answer:

Answer by huippi
There is no universal “best ratio”. You have to use different ratios for different projects. If your motor has high rotation speed but it doesn’t have much torque (it has more torque if it harder to stop using hands) you could use higher ratios likes 50:1 (when motor rotates 50 times wheels rotate only once), but if your motor has high torque but low speed you could use lower ratios, even 1:1 over 0.5:1.

You could also measure speed of your car and then grade few ratios or measure how fast your can climb steep hill and then rate all ratios. The last test would maybe produce more useful gear ratio for general use but it always depends how you will use your car.

I am confident that if you will make both tests, plot your measurements and then make your choice based on those measurements you will get good grade.

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