What is Engine Braking?
3 Answers
The so-called "engine braking" is a term in driving behavior, which refers to effectively controlling vehicle speed by utilizing the resistance generated during engine operation. Both "downshifting" and "releasing the throttle" commonly mentioned can achieve the purpose of using engine resistance to control speed. Below is relevant information: 1. Definition of Braking: Braking, commonly known as "applying the brakes," is the action of stopping or reducing the speed of moving locomotives, vehicles, other transportation tools, or machinery. The general principle of braking is to fix a wheel or disc on the high-speed shaft of the machine and install corresponding brake shoes, bands, or discs on the machine base to generate braking torque under external force. 2. Advantages of Engine Braking: (1) Due to the differential effect, braking torque can be evenly distributed on the left and right wheels, reducing the possibility of skidding or fishtailing; (2) Effectively reduces the frequency of using foot brakes, avoiding prolonged use of brakes that could lead to increased temperature of the brake friction pads, resulting in reduced braking efficiency or even failure; (3) Vehicle speed is always limited within a certain range, facilitating timely deceleration or stopping, ensuring driving safety. 3. Process of Engine Braking: (1) On slippery surfaces such as tar roads, muddy or icy roads, engine braking should be utilized as much as possible, along with flexible use of the parking brake, minimizing foot braking. If foot braking is necessary, intermittent braking is preferred, avoiding locking the wheels to prevent skidding. (2) On steep roads such as long downhill slopes or rugged mountain paths, engine braking must be used in combination with intermittent braking to control speed. Prolonged use of brakes can affect braking efficiency or even render them ineffective. Therefore, in such situations, it is advisable to stop and rest appropriately, allowing the brake drums and shoes to cool before continuing. (3) When using engine braking, select the appropriate gear based on road conditions and vehicle load, and apply appropriate wheel braking according to the vehicle speed. Too low a gear results in excessively slow speed; too high a gear leads to frequent use of wheel brakes.
When driving a manual transmission car on mountain roads, I most commonly use engine braking. Simply put, it means releasing the throttle without pressing the brake, relying on the engine's resistance to slow the car down. The higher the engine RPM, the more noticeable this braking effect is. For example, when going down a long slope in a lower gear, you can clearly feel the car speed being held back by the engine, which is much safer than constantly using the brakes and also saves brake pads. However, it's important to note that for automatic transmission cars, you need to switch to manual mode to use this technique, as the effect is not obvious in direct D mode. This deceleration method is particularly suitable for slippery roads in rain or snow, as it is stable and won't trigger the ABS to jerk uncontrollably.
As a driver who frequently goes on long-distance trips, engine braking is my secret weapon for controlling speed. The principle is actually quite intuitive: when you release the throttle, the reduced engine air intake is like holding your breath, and the vacuum suction generated by piston movement consumes the kinetic energy of the wheels. The higher the gear in the transmission, the weaker the deceleration effect, so steep slopes require shifting to 2nd or even 1st gear. Once, when I drove a friend's electric car downhill, I found that the one-pedal mode worked just like engine braking when releasing the accelerator, even the brake lights would turn on. The biggest advantage of this deceleration method is reducing heat fade, especially for heavy-duty trucks on long descents—it can be a lifesaver.
