CDL Combination Vehicles TestCombination Vehicle Air BrakesEasy
A driver is inspecting the air brake system on a combination vehicle. When checking the brake pedal free play, what is the maximum acceptable amount of free play before adjustment is required?
- A2 inches
- B1 inch
- C4 inches
- D3 inches
Show answer & explanationAnswer & explanation
Correct answer: A. 2 inches
Excessive brake pedal free play can indicate issues with the braking system, reducing braking effectiveness. The maximum acceptable free play is 2 inches.
Why the other options are wrong
- B. 1 inch is generally too little free play, indicating potential issues or improper adjustment.
- C. 4 inches of free play is highly excessive and would make the braking system unsafe and ineffective.
- D. 3 inches of free play is excessive and indicates a problem that requires immediate attention.
Brake Pedal Free Play Limit
The maximum allowable movement of the brake pedal before resistance is felt, indicating that the brake system is beginning to engage.
- Ensures proper brake system response.
- Excessive free play reduces braking effectiveness.
- Must be checked during pre-trip inspection.
Memory trick: Two feet for two inches of play.