Commercial Driver License (CDL) Class B Practice Test

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Study for the Commercial Driver License (CDL) Class B Test. Study using multiple-choice questions, hints, and explanations. Prepare for your exam effectively!

Practice this question and more.

What is the primary purpose of downshifting?

To activate the retarder
To save fuel
To control speed and improve braking
To increase engine power

The correct answer is: To control speed and improve braking

Downshifting primarily serves the purpose of controlling speed and improving braking, especially in heavy vehicles such as those driven by CDL Class B license holders. When a driver downshifts, they shift to a lower gear, which increases the engine's RPM and allows the engine to provide more engine braking force. This action can reduce the reliance on the traditional brakes, which can help prevent brake overheating during long descents or when navigating challenging terrain. Additionally, downshifting ensures that the vehicle maintains better traction and stability while slowing down, making it safer and more manageable, especially in situations where rapid deceleration is needed. The ability to maintain control over the vehicle’s speed is crucial, particularly in commercial driving where cargo weight and road conditions can significantly impact vehicle dynamics.