Which of the following statements about a vehicle's retarder is FALSE?
- Its use is often restricted in residential areas.
- On a slippery surface, it may make a skid more likely.
- It is more efficient at a higher engine rpm and in a lower transmission gear.
- It is powerful enough to replace the service brakes. ✓
Answer: D. It is powerful enough to replace the service brakes.
The false statement is that a retarder is powerful enough to replace the service brakes.
Why this is the answer
The handbook describes retarders as devices that provide auxiliary slowing and assist the main brake system. They are meant for tasks such as controlling speed on long downgrades without using the main brakes, and engine retarders help save the service brakes for emergency stopping. Even though some retarders can absorb a lot of horsepower, the handbook still treats them as helpers to the service brakes, not as a substitute for them.
Why the other answers are wrong
- A. Its use is often restricted in residential areas. — The supplied passages do not mention residential-area restrictions, so this is not the statement the handbook evidence identifies as false.
- B. On a slippery surface, it may make a skid more likely. — The supplied passages do not discuss slippery surfaces or skids, so this is not the statement the handbook evidence identifies as false.
- C. It is more efficient at a higher engine rpm and in a lower transmission gear. — The supplied passages do not discuss retarder efficiency by engine rpm or transmission gear, so this is not the statement the handbook evidence identifies as false.
Remember it
Think of a retarder as a helper that shares the slowing job with the service brakes, not as a stand-in for them.