A hydraulic retarder is used to supplement the vehicle braking system and is electronically controlled. Which technician is correct?

• A. Technician A
• B. Technician B
• C. Both Technician A and Technician B
• D. Neither Technician A nor Technician B

Answer: (C)

Both are correct. A hydraulic retarder acts as an auxiliary braking device that adds braking torque in the driveline, slowing the vehicle without relying solely on the service brakes. This helps reduce heat and wear on the main brakes, especially on long descents or during sustained braking. It’s electronically controlled, so the vehicle’s braking control system modulates the retarder’s output to provide appropriate deceleration, coordinating with other braking components. So describing it as a supplement to the braking system and noting its electronic control are both accurate aspects of how it works.