What are the reasons for the parking brake of large vehicles failing to hold the car?
2 Answers
Large vehicles' parking brakes failing to hold the car may be due to prolonged use of the parking brake, causing the steel cable to undergo plastic deformation. Principle of the parking brake: The professional term for the parking brake is auxiliary brake, which differs in principle from the main brake system. It uses a steel cable linkage to apply braking force to the vehicle. Precautions: The parking brake is a highly utilized system, and only proper and correct usage can ensure smooth operation in the long term. Mechanical parking brakes, which are the most common type, should be used according to correct methods. The parking brake system also includes return springs. When the parking brake is engaged, the spring is stretched; when released, the spring returns to its original length. With prolonged use, these springs can also undergo corresponding deformation.
As a truck driver with years of experience, I've encountered several instances where the parking brake failed to hold, especially when parking on slopes, which was particularly dangerous. The main reasons are usually loose or improperly adjusted brake cables, resulting in insufficient tension when pulled; or severely worn brake shoes, where the friction material is nearly depleted, making it ineffective at locking the wheels. Additionally, rainy, snowy conditions or oil spills can significantly reduce braking effectiveness. Once, I neglected timely checks and nearly caused an accident. Now, I've developed a habit: during maintenance every three months, I have the parking brake tension tested to see if the vehicle slides when engaged; I also try to park on level ground to avoid rollaway risks. Large vehicles are inherently heavy, putting more stress on the braking system—don't skimp on maintenance costs, safety is paramount. Also, avoid overloading the vehicle, as it increases brake strain and can lead to long-term issues.
