Correct: Friction between brake shoes and drums generates significant heat, which brakes are designed to absorb and dissipate. Understanding this helps explain why overheating is a real risk during extended or repeated hard braking.

Correct: Because spring brakes work in combination with the service brakes, their holding power is directly affected by the adjustment of the service brakes. Keeping service brakes properly adjusted ensures reliable parking brake performance.

Correct: When the ABS warning light comes on or stays on, you should continue driving normally while also arranging to have the vehicle serviced. The brakes will still function, but the ABS system may not provide its full protective benefit until the issue is corrected.

Correct: When only the tractor has ABS and the trailer begins to swing out, releasing the brake pedal reduces the braking force causing the trailer to push out of alignment. This technique helps restore stability and prevent a jackknife.

Correct: The three air brake systems are the service brake, the parking brake, and the emergency brake, each designed for a specific use. Knowing all three by name helps with inspections, testing, and regulatory compliance.

Correct: When the steering wheels lock up, the vehicle can skid, jacknife, or spin depending on the conditions — all of which are serious loss-of-control events. Maintaining steering control through proper braking technique is essential to safe emergency stops.

Correct: The supply pressure gauge shows how much compressed air is currently stored in the air tank, giving the driver a real-time view of available braking power. Monitoring it regularly is an important part of safe operation.

Correct: Although automatic slack adjusters are designed to self-adjust, they can still require manual adjustment in some situations, such as after brake component replacement or when inspections reveal improper adjustment. Always follow manufacturer guidance when making adjustments.

Correct: Brake lag is the term for the time it takes compressed air to travel through the lines and fully engage the brakes after the pedal is pressed. Recognizing this delay is essential for accurate stopping distance awareness at highway speeds.

Correct: ABS may or may not result in faster stopping depending on the surface and conditions — it may even increase stopping distance on loose surfaces. The key benefit of ABS is preserving steering ability during hard braking, not necessarily reducing stop distance.

Correct: Front wheel brakes provide reliable stopping power in all weather conditions, including wet or icy roads. Drivers should feel confident relying on them as part of the full braking system.

Correct: Air brakes add approximately one-half second of lag time compared to hydraulic brakes, during which the vehicle continues moving before braking takes effect. At 55 mph, this accounts for about 32 additional feet of travel before braking begins.

Correct: The service brake system is the one that engages and releases through the brake pedal during normal operation. It is the primary system used for all routine braking while the vehicle is in motion.

Correct: In controlled braking, the goal is to apply firm, steady pressure just below the point of lockup so the wheels keep rolling. This preserves steering ability and helps achieve a controlled, stable stop.

Correct: Controlled braking requires sufficient compressed air in the tanks to generate and maintain braking pressure. If air supply is low, the brakes may not respond consistently, making controlled braking techniques unreliable.

Correct: The S-cam rotates when the brakes are applied, pushing the brake shoes outward against the drum to create stopping friction. It is a key mechanical component in the foundation brake assembly.

Correct: Total stopping distance is calculated from perception distance, reaction distance, brake lag distance, and braking distance — not vehicle speed itself. Speed influences how long each of those phases takes, but it is not a separate distance component.

Correct: On dry roads at 55 mph, brake lag accounts for approximately 32 feet of travel before the brakes fully engage. Knowing this helps drivers appreciate the importance of maintaining safe following distances.

Correct: The governor stops the compressor when tank pressure reaches approximately 120–125 psi, preventing the system from over-pressurizing. This automatic regulation is essential for safe and consistent system performance.

Correct: Spring brakes use powerful coil springs that automatically press the brakes on if air pressure drops too low. This failsafe design ensures the vehicle stops safely in the event of a pressure loss.