What is the relationship between car gears and speed?
4 Answers
It is recommended to drive at 15 km/h in 1st gear, 25 km/h in 2nd gear, 35 km/h in 3rd gear, 55 km/h in 4th gear, and 65 km/h in 5th gear. Car transmission: The car transmission is a gearbox containing many gears. The driving gear (connected to the engine via the clutch) receives power from the engine to drive the driven gear (connected to the wheels via the main reducer and drive shaft), thereby rotating the wheels. Each gear has a pair of driving and driven gears, and engaging a specific gear means connecting that particular pair of gears to transmit power. Introduction to gears: P gear is the parking gear, used for long-term parking; R gear is the reverse gear, engaged when the vehicle needs to move backward; N gear is the neutral gear, used when the vehicle is parked for a short time without turning off the engine; D gear is the drive gear, where the transmission automatically shifts gears based on throttle opening and speed data when the gear lever is placed in D.
After driving for so many years, I'm quite familiar with the relationship between gears and speed. Starting off in low gears, like first or second, gives slower speed but more power, ideal for climbing hills or in heavy traffic. On the highway, shifting to higher gears, such as fifth or sixth, allows the speed to stabilize above 100 km/h while reducing engine RPM, making the ride quieter and more fuel-efficient. It's important to match gear shifts with speed properly, keeping the tachometer between 2000 and 3000 RPM for optimal performance. If you accidentally use a high gear at low speeds, the car will struggle to move, making starting difficult and consuming more fuel; using a low gear at high speeds causes the RPM to skyrocket, wasting fuel. In the city, I often manually shift gears to adapt to road conditions—automatic transmission cars are convenient but still require attention to mode selection. Additionally, using lower gears to control speed on rainy days is safer, helping to avoid skidding. Proper matching over the years reduces wear and tear, saves on repair costs, and makes the driving experience smoother.
Gears are like switches in the transmission, controlling the relationship between engine rotation and wheel speed. Vehicle speed is the actual speed we're traveling at. When using lower gears, the vehicle speed is slower but the engine spins faster, providing more power; after shifting to higher gears, the vehicle speed increases while engine RPM decreases, making the ride smoother. Poor matching can cause problems: shifting to high gear at low speed makes the car feel sluggish; shifting to low gear at high speed causes the engine to scream at high RPMs, wasting fuel and damaging components. Automatic transmissions usually handle this automatically, but manual transmissions require our own adjustments. I often remind myself to shift gears based on speed changes - for example, using third gear around 30 km/h and top gear above 80 km/h. This allows the engine to operate efficiently, reduces malfunctions, and extends vehicle lifespan. Remember to return to neutral when parking to protect the transmission - developing good habits saves trouble and money.
When I was learning to drive, I was really confused about why gear and speed had to be matched. The instructor taught me to start in first gear, gradually pressing the accelerator to pick up speed; then shift to second and third gears when reaching over 20 km/h. Now I understand: lower gears provide slower speed but more power, making uphill driving easier; higher gears offer faster and smoother speed, making highway driving more effortless. If you shift incorrectly—for example, starting in a high gear—the car will shake violently for a moment; if you shift to a low gear at high speed, the noise becomes deafening, as if the engine is about to explode. At first, I only focused on the speedometer to shift gears, but later I learned to watch the tachometer and keep it within the optimal range. Every time I hit the road, I still need to practice—smooth shifting makes driving safer. In rainy or foggy weather, using lower gears helps control speed and prevent skidding. After driving a few times, it becomes second nature. Beginners often overlook this, but learning it early reduces stress.
