Which of the following is an auxiliary braking system?

• A. ABS Interface
• B. Jacobs Engine Brake
• C. Transmission Retarder
• D. Thelma Brake Retarder

Answer: (B)

Auxiliary braking systems slow the vehicle using methods other than applying the wheel brakes. A Jacobs Engine Brake, commonly called a Jake brake, is the classic example. When engaged, it changes the engine’s valve timing to convert part of the engine’s energy into drag, creating resistance in the drivetrain and slowing the vehicle without using the service brakes. This helps control speed on descents and reduces wear on the wheel brakes.

The ABS interface is part of the anti-lock braking system and its role is to modulate brake pressure to prevent wheel lock, not to provide extra deceleration. Other options represent different braking devices, but the engine brake is the standard example of an auxiliary braking system.