AG Mechanics CDE Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The correct answer is D. Throttle. In a carburetor, the round disc mounted on a shaft that is located beyond the main fuel nozzle is known as the throttle. The throttle controls the amount of air that enters the engine, which in turn affects the fuel-air mixture ratio for combustion. By adjusting the throttle, the operator can regulate the engine speed and power output.

Options A, B, and C are not correct in this context:

- An air filter is a component that removes particulates from the air before it enters the engine for combustion. It is not directly related to the disc mounted on a shaft in a carburetor.

- A choke is a valve that restricts air flow to the carburetor to enrich the fuel-air mixture when starting a cold engine. It is also not the round disc mounted on a shaft in a carburetor.

- A float is a component in the carburetor that controls the fuel level in the float chamber. It is not the disc mounted on a shaft in a carburetor beyond the main fuel nozzle.