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# Electric Scooter Transmission2

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## Electric Scooter Transmission

(OP)
We are a group of students working on a corporate project developing an electric scooter. We have been working on the system, but are having problems finalizing the exact ratios of gears. This is because of the problem we are facing in calculating the exact torques required at various driving conditions. We would be happy if someone could throw light on how to calculate the torques required for a scooter when the scooter is under development.
Hope to hear from someone soon.

### RE: Electric Scooter Transmission

If you go to my webpage then you will see how we approached the rather more complex problem of estimating the energy usage for our solar car. It does include the vehicle resistance equation. http://www.geocities.com/greglocock/index.html

Your big problems are 4 fold

1) determining the rolling resistance of your tyre. The manufacturer may be able to help, or you could measure it yourself (I recommend this, it is amazing what you learn). We used a large cylinder of steel, of the corect weight, and two wheels, rolling down a ramp and onto a level surface.

2) determining your air resistance - may or may not be important for your speeds - should be plenty of estimates of Cd around for a bike. 1 would be a good start

3) what gradients do you need to climb, at what speed?

4) the efficiency of your gearbox.

Cheers

Greg Locock

### RE: Electric Scooter Transmission

How about an infinite ratio "transmission"? A great design in use now by Yamaha. Wherein a belt drive is the clutch,trans,etc. A fixed pulley is attached to the crankshaft. While a variable clutch pulley is hooked to the rear wheel drive. The infinite drive works like this.The pulley consist of two halves.Spring loaded to keep them a predetermined distance apart. The belt at idle "slips" around the pulley. As engine speed increases the belt is "driven" up to the larger diameter section of the pulley. Its crossection also gets smaller to grip the belt.The faster the engine speed the higher the belt climbs up the larger part of the pulley,crossection closes up ,etc.Till it is at its highest rate of speed.Great for low powered vehicles,it only uses what "gear it can" Terrible description of how this works,but I hope you get the idea. Craig...Maybe Greg can elaborate!!

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