Final answer:
The starter gear disengages from the wheel to prevent damage to the starter motor and engine. This is achieved through the use of an overrunning clutch, which allows the gear to rotate freely in one direction but not the other. This mechanism protects the starter motor and prevents excessive wear and tear on the system.
Step-by-step explanation:
The starter gear disengages from the wheel in order to prevent damage to the starter motor and the engine. When the engine starts, the starter gear is designed to mesh with the engine's flywheel and rotate it. Once the engine is running, the starter gear needs to disengage to prevent it from spinning too fast and causing damage. This disengagement is achieved through the use of a device called an overrunning clutch, also known as a freewheeling clutch. This clutch allows the starter gear to rotate freely in one direction, but not in the opposite direction. So when the engine starts, the flywheel rotation causes the starter gear to rotate faster than the starter motor, disengaging it from the wheel and allowing it to spin freely. This mechanism protects the starter motor from damage due to excessive speed and prevents unnecessary wear and tear on the starter system.