Ohio CDL Practice Test 2025 - Complete Exam Preparation Guide

The purpose of air brakes in commercial vehicles is to slow down or stop using compressed air. Air brakes operate on the principle of utilizing compressed air to activate the braking mechanism, which allows for greater control and stopping power, especially in larger trucks and buses. This system is particularly effective in heavy vehicles as it provides the necessary force to handle the additional weight and momentum.

Air brakes are essential for achieving safe stopping distances, particularly under loaded conditions or on inclines, where traditional hydraulic brakes may not provide sufficient braking power. The use of air also allows for a more reliable braking system that can be easily serviced and maintained in commercial vehicle applications. Therefore, the correct option highlights the main functional aspect of air brakes and underscores their importance in the safety and effectiveness of commercial vehicle operations.