Question 199Motor Plants - Assistant Engineer

The correct answer is B) spring force. Starting air check valves are held firmly on their seats by spring force. The spring provides the necessary force to keep the valve closed and sealed against the valve seat, preventing backflow of air when the starting air system is not in use. The other answer choices are incorrect because: A) Cam rollers on the camshaft are not involved in the operation of starting air check valves. C) and D) Air pressure is not the primary mechanism for holding the starting air check valves in place; it is the spring force that keeps the valves firmly seated.