Conventional wheel-rail system drive principle

The principle is that the wheel creates a friction with the ground as it rotates. Suppose this friction is very small, or even zero. Then the phenomenon is that the wheels slip in place, the car will not move forward (or backward). Suppose the friction is very large, or even infinite, then the phenomenon is that the wheels are purely rolling on the ground. Because the wheel and the car are one, it will drive the car forward (or backward). And the wheel and the car is connected by rolling bearings, frictional resistance is very small, so the general resistance of the car, that is, the frictional resistance of the wheel and the body, as well as the wind resistance.