Texas CDL General Knowledge Practice Exam

During a pre-trip inspection, it is crucial that you check the brakes and suspension system components for the presence of oil, grease, or brake fluid. These substances can indicate potential leaks or malfunctions which could compromise the effectiveness of the braking system. For instance, oil or grease on brake components can lead to decreased friction, making it more difficult for the brakes to function properly. Similarly, the presence of brake fluid could suggest a leak in the brake lines, which could ultimately result in brake failure.

While substances like rust, mud, or dirt might be observed, they do not necessarily indicate a functional problem in the same direct manner as oil and grease. Rust can be an indicator of age or weather exposure, but it does not automatically signify a failure unless it's severe enough to affect component integrity. Therefore, keeping brake and suspension systems free of any oil, grease, or brake fluid is essential for maintaining safe vehicle operation.