Ch.2: Playing with gears

In this chapter, I learned the relationships between two gears, one on the motor and one on the axle.
This determines, how fast or slow the wheel moves, and is very important in changing the speed by changing the gear.

I think, this relationships of two gears are also included in the car. I heard that, as driver changes the gear, it means that the relationships of gear changes whether to big to small, or small to big.

I read in the chapter that, there are three relationships of gears.

If I have a large gear on the motor and a small gear on the axle, then the robot will move faster, as small gear on the axle turns more than the large gear on the motor. It is because of the difference of circumference. As the large gear on the motor rotates once, the small gear on the axle rotate more than once. The small gear on the axle has less circumference and it always rotates more than the large gear on the motor. Therefore, the small gear on the axle (which is actually wheel) rotates more, in the one rotation of the large gear on the motor, and the robot will move faster.

If I have a small gear on the motor and a large gear on the axle, then the robot will move slower.
It is just opposite of my first statement. The small gear on the motor has less circumference than the large gear on the axle, so I can easily know that small gear rotates more. Moreover, in order to rotates the large gear on the axle once, the small gear on the motor has to rotates more than once. Therefore, the large gear on the axle (which is wheel) rotates once, in the many rotations of the small gear on the motor, so the robot will move slower.

If I have a same gears on the both side, the motor and the axle, then the speed will be moderate (just only depends on the speed of motor in the program, or size of the wheel). It is because that, there is no difference between two gears, as they have exactly same circumferences. There is nothing about rotates more or less, as they rotate same amount. Therefore the speed does not change, as they rotates together, in same amount of circumferences.