Arkansas Commercial Driver License (CDL) Practice Test

When is the braking effect the greatest?

1. Near the governed RPMs with transmission in low gears

2. At high RPMs with transmission in high gears

3. At low RPMs with transmission in high gears

4. At idle with transmission in low gears

The correct answer is: Near the governed RPMs with transmission in low gears

The correct answer highlights that the braking effect is greatest near the governed RPMs with the transmission in low gears. When a vehicle is running near its governed RPMs in a low gear, the engine's power is effectively harnessed, allowing for maximum braking efficiency. This is due to the engine's ability to provide robust engine braking, which helps to slow the vehicle down more effectively than it would in other scenarios. Using low gears increases the engine's revolutions per minute (RPMs), which enhances engine braking through the compression and friction of the engine's components. The governed RPMs represent the maximum operating speed of the engine, allowing for optimal performance in braking situations. In this context, the engine can work in conjunction with the vehicle's braking system to provide the most effective stopping power. This technique is particularly valuable when descending hills or when needing to slow down rapidly for any reason, as it prevents overheating and excessive wear on the brake components. In contrast, while braking in high gears can provide some stopping power, it is less effective because the engine is not able to provide the same level of resistance as in low gears. Thus, choosing lower gears aligns with maximizing the braking effect.