Torque transmission (Mercedes-Benz E-Class W210)

When the car starts moving, the drive wheels require a lot of torque, while the engine develops little torque at low speeds. In this case, you engage 1st gear, and thanks to its gear ratio, the torque increases, and the rotation of the wheels slows down compared to the engine speed.

When driving on the highway in 5th gear, the opposite occurs. Its gear ratio is such that the engine speed increases when transmitting torque to the drive wheels. Thus, with an almost constant engine speed, the desired wheel speed is achieved.

However, the kinematic connection between the engine and the gearbox can also be interrupted - for example, when you start the engine, are stopped at a traffic light with the engine running, or want to change gears. In cars with a manual gearbox, this task is performed by the clutch. It also allows for a smooth start, since it equalizes the speed of the crankshaft and the input shaft of the gearbox. In an automatic gearbox, the clutch function is performed by a torque converter. The main advantages of an automatic gearbox are the following: the engine does not stall, there is no need to change gears, which makes driving easier.