Air Brake Practice Test

The correct choice indicates that hydraulic brakes are not part of a conventional air brake system. In a conventional air brake system, the primary mechanisms involved are the service brake, parking brake, and emergency brake, all of which utilize compressed air to function.

The service brake is the primary braking system that the driver operates, engaging the brakes when the brake pedal is pressed. The parking brake is designed to hold the vehicle stationary when parked and can also be activated to assist with stopping in emergencies. Emergency brakes, often referred to as spring brakes, are in place to provide a means of stopping the vehicle rapidly in case of a primary system failure.

In contrast, hydraulic brakes operate using the principles of hydraulic fluid pressure to engage the brake pads and discs. They rely on a different mechanism entirely and are commonly found in smaller vehicles, rather than the large vehicles typically equipped with air brake systems. This distinction is critical in understanding the various braking systems utilized across different types of vehicles.