CDL General Knowledge TestAir Brakes (if applicable)Medium
A driver is inspecting the brake drums on a vehicle with air brakes. They notice a significant amount of grease and oil on the inside surface of the brake drum. What is the most significant safety concern posed by this condition?
- AAccelerated wear of the air compressor.
- BReduced air pressure in the brake system.
- CIncreased effective braking surface.
- DContamination of the brake linings, leading to reduced braking power.
Show answer & explanationAnswer & explanation
Correct answer: D. Contamination of the brake linings, leading to reduced braking power.
Grease or oil on the brake linings contaminates the friction material, drastically reducing its ability to grip the brake drum. This leads to a severe loss of braking power and can cause the vehicle to pull to one side during braking.
Why the other options are wrong
- A. This condition does not directly affect the air compressor's wear rate.
- B. Contamination of brake drums does not directly reduce air pressure in the system; it affects the mechanical braking effectiveness.
- C. Grease and oil reduce, not increase, the effective braking surface and friction.
Brake Lining Contamination
When foreign substances like grease, oil, or brake fluid get onto the brake lining material, impairing its friction properties.
- Causes significant loss of braking power.
- Can lead to uneven braking.
- Requires immediate replacement of contaminated parts.
Memory trick: Grease on the brake, a dangerous mistake.