Question 183Motor Plants - Assistant Engineer

The correct answer is B) The air starting valve is opened by cam action. The air starting valve, labeled "III" in the illustration, is a component in the engine's air starting system. This valve is responsible for allowing compressed air to enter the engine cylinder to facilitate starting. During normal engine operation, the air starting valve is not constantly opening and closing, as described in option A. When the engine is being started, the air starting valve is opened by the cam action of the engine, allowing the compressed air to flow into the cylinder and crank the engine. This makes option B the correct answer. Options C and D are incorrect, as the air starting valve is not closed when starting air is secured, nor is it held open by air pressure during the starting process.