Which shutoff valves should remain closed?

The correct answer indicates that the rear shutoff valves should remain closed. This is important for maintaining proper vehicle operation and safety. Keeping the rear valves closed prevents the potential for unintentional leakage or flow of fluids, which can create hazards such as spills or loss of pressure in a system that relies on fluid control.

In many vehicles, especially commercial trucks and buses, the rear valves are critical in controlling the flow of essential systems like fuel, air, or hydraulic fluid. If these valves were left open, it could lead to significant operational issues, affecting performance and safety. Therefore, understanding when and why to keep certain shutoff valves closed is vital for any CDL holder to ensure the safe and efficient operation of their vehicle.

While front and middle valves are also important, the focus on the rear valves in this context highlights their critical role in vehicle safety and fluid management.