What Does Engine Braking Mean?
2 Answers
Engine braking refers to the braking effect on the drive wheels generated by lifting the accelerator pedal without depressing the clutch, utilizing the compression resistance, internal friction, and intake/exhaust resistance produced during the engine's compression stroke. Essentially, it means driving in gear without applying throttle, where the engine provides no traction to the vehicle. Instead, the rotation of the wheels drives the transmission system, and the idling engine generates a counteracting resistance on the vehicle. The higher the gear, the lesser the engine's effect on the vehicle, and vice versa. Engine braking is the process where the wheels overcome the engine's resistance to brake. Once the engine's passive speed reaches a certain threshold, it stops fuel injection, achieving fuel-saving purposes. Additionally, engine braking reduces wear on brake pads, extending their service life.
I love using engine braking when driving a manual transmission car on mountain roads. When going downhill for a long distance, I shift to a lower gear without stepping on the accelerator. The engine RPM will soar, but the speed is actually held back, which is especially good for saving brake pads. This essentially cuts off the fuel supply, causing the piston movement to be hindered, and utilizes the internal resistance of the engine to slow down. Veteran truck drivers call this 'gear braking,' which is much safer than just using the brakes, especially on rainy or snowy days when tire traction is poor. It’s both stable and prevents brake overheating and failure. However, be careful not to shift into too low a gear, as sudden traction force can cause the rear wheels to skid.
