Answer :
Final answer:
Spring brakes typically engage at approximately 20 to 45 psi, but the provided options do not match this range. Option c) 40 psi is closest to the typical engagement pressure.
Explanation:
The question is about the air pressure at which spring brakes on a vehicle begin to engage or drag. Spring brakes are a safety feature in large vehicles such as trucks and buses. They use springs to apply the brakes automatically if the air pressure drops too low.
The correct answer is that spring brakes typically begin to drag at approximately 20 to 45 psi; however, this can vary depending on the specific brake system design. Since none of the options provided (60 psi, 80 psi, 40 psi, 100 psi) are within this range, there is no correct answer listed. It is worth noting that 40 psi is closest to the typical engagement pressure, so if forced to choose from the options, c) 40 psi would be the best guess.
