What is the Principle of Engine Braking?
2 Answers
Engine braking principle refers to lifting the accelerator pedal without disengaging the engine, utilizing the compression resistance generated by the engine's compression stroke, internal friction, and intake/exhaust resistance to create a braking effect on the drive wheels. Below are specific details: 1. Slippery Roads: On slippery surfaces such as asphalt roads, muddy or icy roads, engine braking should be utilized as much as possible, along with flexible use of the parking brake, while minimizing the use of foot braking. If foot braking is necessary, intermittent braking is preferable, and one should avoid stomping on the brake pedal to prevent skidding. 2. Steep Roads: On steep roads like long downhill slopes or rugged mountain paths, engine braking must be used in combination with intermittent braking to control vehicle speed. Prolonged use of the brake can affect braking efficiency or even lead to brake failure. Therefore, in such situations, it is advisable to take appropriate breaks, allowing the brake drums and brake pads to cool before continuing the journey. 3. Gear Selection: When using engine braking, it is necessary to select the appropriate gear based on road conditions and vehicle load, and apply appropriate wheel braking according to the vehicle speed. A gear that is too low will result in excessively slow speed, while a gear that is too high will cause the wheel brakes to be used too frequently.
I've been particularly fascinated by the power mechanisms of cars recently, especially engine braking. The principle is quite ingenious: when you release the accelerator pedal, the throttle instantly closes, and the engine suddenly switches to intake mode. As the pistons move within the cylinders, they have to overcome the significant resistance of compressing air, much like the feeling of pushing a bicycle pump while blocking its outlet with your hand. Additionally, the friction generated between the high-speed rotating crankshaft and connecting rods inside the engine plays a role, along with the backpressure in the exhaust pipe. Together, these forces turn the entire engine into an energy dissipater, converting the vehicle's kinetic energy into heat and dissipating it. This natural braking is especially suitable for long downhill stretches. I've tried using this technique on winding mountain roads—it helps maintain a steady speed without constantly applying the brake pads, making it both safe and convenient.
