CDL General Knowledge Practice Test

Wheel lockup during braking primarily occurs due to excessive brake application. When the brakes are applied too firmly, particularly on slippery surfaces, the wheels can stop rotating completely, leading to a loss of traction. This condition can result in skidding, making it difficult for the driver to maintain control of the vehicle. In normal operation, the brakes should be applied progressively to allow the wheels to continue turning, which helps maintain traction and enables steering. Understanding this concept is essential for safe driving, as it emphasizes the importance of controlled braking techniques to prevent skidding and enhance vehicle stability. The other options can influence vehicle performance but do not directly cause wheel lockup in the same way. For instance, low engine power or too much cargo weight can affect the vehicle's handling and braking efficiency, while improper tire pressure can impact overall traction and wear but is not the direct cause of wheel lockup during braking.