Experiment with your own transmission in this manner ;
Put it in first/low gear, leave it in frst gear.
Now as you drive notice the speed of the ENGINE as you go about as fast as you can in this first gear.
when the engine has reached its maximum ability you can’t go any faster.
– how could you possibly go faster ? –
By changing the ratio of gears ( now change to second gear ) so the engine can begin anew at its lower rpm…advancing to its maximum. allowing you to go that much faster …untill …
now you get the picture.
A transmission changes the ratio of the rolling speed versus the engine speed.
You can’t go faster without more gears . The engine only has it maximium. And then what ?
The 10 speed bicycle is a great pesonal experience of this.
Counting is another.
0,1,2,3,4,5,6,7,8,9 in the engine
10,20,30,40,50,60 etc is the transmission
You can’t count past 9 without ‘‘shifting gears’’ to get to 10,11,12,13,14 and so on.
Then you have to shift again 20,21,22,23
Then faster still…30,31,32,33,34,35