What is Transmission System | Function of Transmission System

Introduction to Transmission System :

Transmission system is the system by means of which power developed by the engine is transmitted to road wheels to propel the vehicle. In automobiles, the power is developed by the engine which is used to turn wheels. Therefore, the engine is to be connected to the transmission systems for transmitting power to wheels. Also, there should be a system by means of which engine could be engaged and disengaged with the transmission system smoothly and without shock so that the vehicle mechanism is not damaged and passengers do not feel inconvenience. A clutch is employed in automobiles for this purpose.

The engines employed in automobiles are of very high speed. Hence, a speed reduction is necessary to reduce the speed to moderate level as well as to get the required high torque while moving from rest. For this purpose, a gearbox is employed in automobiles. Figure 3.1 shows the general arrangement of power transmission system of an automobile. The various parts of the system are elaborately discussed in further topics of this unit. The motion of the crankshaft is transmitted to the gearbox through the clutch. The gearbox consists of a set of gears to change the speed according to the requirement. The motion is then transmitted to the propeller shaft from gearbox through a universal joint. The purpose of universal joint is to connect two shafts at an angle for power transmission. The power is transmitted to the differential unit through another universal joint. Finally, the power is transmitted from differential to wheels through the rear end. The differential unit is used to provide the relative motion between two run wheels while the vehicle is taking a turn.

Functions or Purposes of Transmission Systems

1. It enables the running engine to be connected or disconnected from the driving wheel smoothly and without shock.
2. It enables the leverage between engine and driving wheel.
3. It enables the reduction of engine speeds.
4. It enables the turn of the drive round through 90°.
5. It enables the driving wheel to be driven at different speeds.
6. It serves as a safety device by slipping when the torque transmitted through it exceeds a safe value, thus preventing the breakage of parts in the transmission train.