The Need for Transmission System in Cars


In a car, the engine produces the necessary power that is needed for it to move. But it is important to know how this generated power is transferred to the wheels and get them to rotate. There is system in most of the automobiles which is meant for this purpose. A transmission system in a car generally does two tasks.

a) Transfer power from the engine to the wheels
b) manage the gear ratio between the engine and the drive wheels.

The first task is achieved mechanically with the help of gear wheels. But the job of the transmission system does not stop there. The same system should also be used to perform a lot of other functions for optimal performance of the vehicle. This article focuses on the need for the transmission system in a vehicle.

The need for a transmission system in a vehicle arises due to the characteristics of an internal combustion engine. There are two terms that need to be understood here regarding an internal combustion engine. a)Torque b)Power. Torque is the amount of force that is acting upon the rotating shaft which in turn make the wheels rotate. Power is the calculation of the amount of work done , in a specified amount of time. Which in this case, are the rotations of the rotating shaft, other wise called rpm(rotations per minute).

Now, when a vehicle moves, it does not move in an uniform speed. It starts from zero velocity, attains momentum, increases further in speed, then comes down if the vehicle slows down etc., and all of this according to the requirements faced by the movement. So, it becomes important that the rotations achieved by the axle of the vehicle in a minute matches the power generated by the engine (which is also rpm). Imagine a condition where the engine is connected directly to the axle without no transmission mechanism. There are two possibilities.

a) Since the axle is slender, a lot of torque would be required to rotate it, and the engine should be able to deliver it from the beginning. If it does not, there will be too much pressure on the engine to deliver and can sometimes even result in failure.

b) And if the engine is able to deliver, it becomes mandatory that the system that connects the engine to the axle is strong enough to withstand the mechanical pressure. Even if the two conditions are satisfied, if the speed of rotation changes, the calculations change and become unmanageable. Thus it becomes necessary that it is managed by a proper system.

The transmission system maintains an optimality in transferring the power. That is, it relays the power to the axle more optimally, so that the force exerted on the axle is not more or less than required. Simply put, for a certain amount of power generated by the engine, the transmission mechanism ensures there is maximum usage. For example, when the vehicle starts to move, more torque is needed than power, because movement is of priority. As the vehicle attains greater speeds, this condition gradually changes and more power would be of priority than torque. Any engine has a red line – it’s the maximum rpm value in which the engine can perform. The transmission system ensures that the engine stays below the red line and near the rpm band of its best performance.

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