Answer :
The correct option is a. to open the valves a greater distance. The rocker arm ratio is used to open the valves further for better engine airflow and performance by acting as a lever that magnifies the movement of the cam lobe at the valve end.
The rocker arm ratio is used in most valve trains primarily to open the valves a greater distance without requiring a drastically different camshaft profile. The rocker arm acts as a lever; thus, a higher ratio means a smaller movement at the cam lobe will translate into a larger movement at the valve end. This allows for better airflow into and out of the combustion chamber, improving engine performance and efficiency.
It is important to note that while a higher rocker arm ratio can indeed open the valve further, it does not inherently decrease the force against the camshaft, as options b, c, and d might suggest. Instead, the force on the camshaft may increase due to the greater leverage exerted by the rocker arm. The correct option is a. to open the valves a greater distance.
