Which of the following statements about a vehicle's retarder is FALSE?
- Its use is often restricted in residential areas.
- It is powerful enough to replace the service brakes. ✓
- It is more efficient at a higher engine rpm and in a lower transmission gear.
- On a slippery surface, it may make a skid more likely.
Answer: B. 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 calls engine brakes, retarders or auxiliary brakes devices that slow the vehicle and help avoid excessive brake temperature. Because it describes them as assistance, it does not support the idea that a retarder can take the place of the service brakes. The supplied passages say nothing about residential restrictions, engine rpm or gear selection, or skids on slippery surfaces, so the reliable point from the text is that a retarder is an auxiliary aid, not a replacement.
Why the other answers are wrong
- A. Its use is often restricted in residential areas. — Nothing in the passages makes this the false statement, and they do not discuss residential-area restrictions on retarder use.
- C. It is more efficient at a higher engine rpm and in a lower transmission gear. — The passages do not mention engine rpm or transmission gear, so the handbook text does not show this to be the false statement.
- D. On a slippery surface, it may make a skid more likely. — The passages do not discuss skids on slippery surfaces or retarders in that situation, so this is not the statement the text contradicts.
Remember it
Think of a retarder as an assistant, not a substitute: it helps slow the truck and spare the brakes.