What Does Rear Axle Ratio Mean?
2 Answers
Rear axle ratio is an important parameter of the engine, commonly known as the rear axle ratio. Its academic name is the final drive ratio. The ratio of the vehicle's drive axle, which is the ratio of the final drive assembly, can be understood as amplifying the torque transmitted from the driveshaft, essentially determining how much force is needed to make the car move. More details are as follows: 1. The larger the ratio, the greater the output torque, but the slower the output speed. To achieve greater power (torque) output for the vehicle, suitable for climbing or heavy loads, a relatively larger final drive ratio (e.g., 6.83) can be selected to meet the demand, but this sacrifices speed. 2. The smaller the ratio, the smaller the output torque, but the faster the output speed. By choosing a relatively smaller final drive ratio (e.g., 3.89), the need for higher speed can be achieved. 3. All vehicle rear axles are equipped with a reducer to attenuate the speed from the driveshaft. The ratio here refers to the gear ratio. For example, if the driveshaft speed is 4.1r/s, it will be reduced to 1r/s (referring to rotational speed). The 'plateau gear' is the optimal gear ratio set for vehicles on specific high-altitude terrains, such as a ratio of 4.3, while the 'plain gear' is the optimal ratio set for vehicles on plains or highways, such as 4.1. The optimal gear ratio varies for different vehicles, helping the engine operate under optimal conditions and minimizing gear wear.
The rear axle ratio is essentially the gear ratio in the vehicle's rear axle system, indicating how many times the engine turns for each rotation of the wheels. When driving a family SUV, I paid special attention to this parameter. Simply put, higher ratios like 3.73 or 4.10 mean the engine turns more while the wheels turn less, providing greater torque, which is particularly useful for climbing hills or towing. Lower ratios like 2.8 mean the engine turns less while the wheels turn more, making them ideal for highway cruising, offering quieter engine operation and better fuel efficiency. My car is a standard family model with a 3.55 ratio, delivering moderate fuel consumption on long trips but slightly sluggish acceleration, requiring a heavier foot on steep hills. When buying a used car, I compared ratios across different models and found that choosing the wrong one can affect daily driving comfort and fuel expenses—too high, and the engine roars on the highway with soaring fuel consumption. My advice: opt for lower ratios for city commuting and higher ones for frequent hauling or off-roading.
