Answer :
Final answer:
a) Fully pressurized, The tractor should not be moved until the air system is fully pressurized after pushing in the trailer supply valve to ensure braking systems work effectively and to prevent safety risks.
Explanation:
After pushing in the trailer supply valve, you should not move the tractor until the air system is fully pressurized. It's essential for safety and optimal performance of the tractor-trailer's braking systems that the air supply systems are properly pressurized before motion. This pressurization ensures that the pneumatic systems, which operate the brakes and other components, have adequate air pressure to function effectively. Attempting to move the vehicle before the system is fully pressurized could lead to brake failure or diminished braking capability, posing serious safety risks.
