What are the adverse consequences of continuously using the service brake on long downhill slopes?
3 Answers
Continuously using the service brake on long downhill slopes can lead to adverse consequences: it causes the brake temperature to rise, resulting in a sharp decline in braking effectiveness. If the brake is continuously applied on a long downhill slope, the brake pads will overheat, leading to reduced braking force. In severe cases, this can result in a complete loss of braking ability, causing brake failure. Therefore, when descending a long slope, it is advisable to use a lower gear and employ engine braking. Engine braking refers to lifting the accelerator pedal without depressing the clutch, utilizing the compression resistance generated by the engine's compression stroke. This creates internal friction and intake/exhaust resistance, which applies a braking effect on the drive wheels. Simply put, it means driving in gear without supplying fuel, so the engine no longer provides traction to the vehicle.
I've been in freight transport for over a decade, and long downhill sections are what I fear most. If you keep your foot on the brake continuously, the brake pads will glow red enough to light a cigarette! The high temperatures can warp the brake discs and grind the entire brake pad into iron dust. The most dangerous part is when the brake fluid boils and forms bubbles, making the pedal feel as soft as stepping on cotton—this can be deadly. I've personally witnessed several large trucks lose their brakes on steep descents and plunge off cliffs. Remember this veteran driver's advice: shift to a lower gear in advance, let the engine control your speed, and combine light braking with exhaust braking—that's the life-saving trick.
Last time I drove the Sichuan-Tibet Highway, I encountered a continuous 20-kilometer downhill slope. At first, I foolishly kept pressing the brakes. By the time I reached the mountainside, I smelled burning, the brake pedal started shaking, and all the warning lights on the dashboard lit up. Later, the mechanic said the high temperature caused bubbles in the brake fluid lines, and the brake pads were severely carbonized. The worst part was that the brake discs developed blue cracks from overheating, and the entire braking system was ruined. Now I’ve learned my lesson—when facing a long downhill slope, I directly switch to manual mode and lock it in 3rd gear. The engine whines to help slow down, and my right foot can actually relax and rest.
