What is the air pressure for brakes on a cargo truck?

• A. 40 psi
• B. 60 psi
• C. 80 psi
• D. 100 psi

Answer: (B)

Air brakes rely on compressed air to apply and release the brakes, so having a sufficient pressure is essential for safe stopping. The system is designed so that you still have effective braking and a warning when pressure gets low, with sixty psi serving as the key minimum threshold for normal brake operation. If pressure drops to this level, you’ll typically see a low-pressure warning, reminding you to recharge the system; below it, braking performance can degrade and the spring brakes can engage in an emergency/parking situation. The normal charged state of the system is higher (often around full charge), but sixty psi represents the critical minimum for the brakes to function reliably. That’s why sixty psi is the correct value.