If my understanding is correct, a car (in simple terms) has;
- The crankshaft, then;
- The clutch and gearbox, then;
- The propshaft, then;
- The differential, then;
- The driveshafts and the wheels.
Therefore, assuming the car is in gear and the clutch pedal is not pressed, surely turning the crankshaft would turn the wheels, and move the car? If this is not the case, which component can spin without spinning the component it is connected to (other than the clutch)?