Every self-propelled road-going vehicle needs some form of transmission to take the output from its power unit to the driven wheels.
每一个自带动力驱动的道路行走车辆需要一个变速装置来将发动机的动力传输到车轮.
The vast majority of vehicles are powered by internal combustion engines, and a large part of the task of the transmission in these vehicles is to compensate for the inherent drawbacks of the engine -in particular, its need to remain running when the vehicle is stationary, and the limited range of speed within which it develops sufficient torque to drive the wheels.
大部分车辆都靠内燃机驱动,变速装置的主要作用在于补偿发动机内在的不足,特别是在车辆停止运动,发动机仍然需要保持运转的时候.还有一个作用就是保持在一定的速度下保持驱动车轮足够扭矩.
To overcome the first problem ,some kind of clutching arrangement is necessary.
第一个问题,就需要用离合器来解决.
To overcome the second, the transmission needs to include a gearbox providing a range of different ratios of input to output speed, enabling the engine's speed to be maintained within the useful range of torque output over a more or less wide range of vehicle speeds.
对于第二个问题,可利用变速箱来安排不同的输入输出比,使发动机保持一定的转速,以便提供保持车辆速度的有效扭矩输出.
So important have these solutions become that"transmission" has in many minds come to mean that part of the system between the engine output and the gearbox putput, neglecting the many complexinties which exist between the gearbox output and the driven wheels..
所以,作为发动机输出和变速箱输出连接纽带的“传动”系统,就非常重要.（此处不考虑变速箱输出同从动轮之间的复杂关系）