What is a truck gearbox overdrive

Overdrive is defined as a gear with a transmission ratio of less than 1(i. e. I & LT; 1) , which means that the output shaft of the transmission is faster than the input shaft, and the transmission ratio of overdrive is generally 0.7-0.85

Overdrive is mainly used for light loads on good roads to improve fuel economy. But if the power of the engine is not high, the overspeed gear utilization rate is very low, fuel-saving effect is not significant, and even affect the power of the car！

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