getting very tired, because his pedals were difficult to push. In other words, his pedals required more force than Dave’s did. So does Dave expend less energy going up the same hill? Dave expends half the energy per pedal revolution, but this is only because he goes half the distance per pedal revolution. Dave has to pedal twice as many times to get up the hill. So, the energy expended both Dave and Jeff going up the entire hill is the SAME in either case. So, the bottom line is, when we gain a speed advantage, we are losing the force advantage. The pedals are more difficult to turn. You can gain either speed or force advantage, but not at the same time. Selecting the Proper Gear Ratio So, how can you choose the best gear ratio? Experimentation is probably the easiest way to find out. The idea is that your motor, like your legs when you ride a bike, like to go a certain speed. They also have a limit as to how much force they can exert. First you must find the speed at which the motor gives the most power (this is usually half the speed the motor will rotate if there is no load, or force, exerted on the motor shaft). Try to keep the motor turning at approximately that speed as you experiment with different gear ratios. It helps if you build your car in such a way that you can change the gear ratios easily as you experiment. Remember, the ideal gear ratio may change some if you change different characteristics of your car (size, weight, etc.). Just remember, if your car is not going very fast it can either be that the wheel speed is too slow, or (like Jeff riding uphill) the force required to turn the wheel is too high. Try a different gear ratio! Materials The materials you choose vary greatly depending on the type of transmission you build. If you decide to build a belt drive, try stiff, rubbery materials for the belt - such as a slice of inner tube or an o-ring. Make sure your pulleys are pulled away from each other so that the belt is tight. One suggestion: one way to change the
getting very tired, because his pedals were difficult to push. In other words, his pedals required more force than Dave’s did. So does Dave expend less energy going up the same hill? Dave expends half the energy per pedal revolution, but this is only because he goes half the distance per pedal revolution. Dave has to pedal twice as many times to get up the hill. So, the energy expended both Dave and Jeff going up the entire hill is the SAME in either case. So, the bottom line is, when we gain a speed advantage, we are losing the force advantage. The pedals are more difficult to turn. You can gain either speed or force advantage, but not at the same time. Selecting the Proper Gear Ratio So, how can you choose the best gear ratio? Experimentation is probably the easiest way to find out. The idea is that your motor, like your legs when you ride a bike, like to go a certain speed. They also have a limit as to how much force they can exert. First you must find the speed at which the motor gives the most power (this is usually half the speed the motor will rotate if there is no load, or force, exerted on the motor shaft). Try to keep the motor turning at approximately that speed as you experiment with different gear ratios. It helps if you build your car in such a way that you can change the gear ratios easily as you experiment. Remember, the ideal gear ratio may change some if you change different characteristics of your car (size, weight, etc.). Just remember, if your car is not going very fast it can either be that the wheel speed is too slow, or (like Jeff riding uphill) the force required to turn the wheel is too high. Try a different gear ratio! Materials The materials you choose vary greatly depending on the type of transmission you build. If you decide to build a belt drive, try stiff, rubbery materials for the belt - such as a slice of inner tube or an o-ring. Make sure your pulleys are pulled away from each other so that the belt is tight. One suggestion: one way to change the
221826-59c2b4dd-5380-4973-9a36-6b15d0c585a0.docx