CDL Vehicle Combination Practice Test

What is the maximum allowable air leakage rate for a combination vehicle when the engine is off and brakes are off?

1. 1 psi per minute

2. 5 psi per minute

3. 3 psi per minute

4. 10 psi per minute

The correct answer is: 3 psi per minute

The maximum allowable air leakage rate for a combination vehicle, when the engine is off and the brakes are off, is typically set at 3 psi per minute. This standard is essential for ensuring that the braking system remains functional and can maintain its air pressure, which is crucial for safe operation. If a vehicle were to leak air at a higher rate, it could indicate an issue with the air system, such as a defective hose, a problem with the air tanks, or a malfunctioning valve. A leakage rate exceeding this standard could compromise the ability of the vehicle to stop efficiently, leading to dangerous situations on the road. Thus, knowing and adhering to this specific limit is pivotal for drivers and safety inspectors, ensuring that the vehicle can operate safely without risking brake failure due to insufficient air pressure in the braking system.