Question

Liquid brakes in automobiles follow the principle of brahma press (Pascal’s principle). What about air brakes? Collect the information about the working process of air brakes.

Answer 1

Hint : To answer this question, we need to consider the phenomenon behind Pascal's principle which is applied in the working of liquid brakes. Then we have to relate this phenomenon with the air brakes.

Complete step by step answer
Pascal's principle states that if pressure is applied anywhere on a fluid, which is contained inside a vessel, then it is equally transmitted in all the directions. This principle is the basis for the Liquid brakes which are used in automobiles.
We know that the air is also a kind of fluid. Since the Pascal’s law is valid for any type of fluid, so the air brakes also work on the principle similar to that of the hydraulic brakes, that is, the Pascal’s principle.
When the driver of such vehicles presses the brake pedal, the compressor which is mounted on the engine compresses the air, which is pumped into the storage tanks used for storing the air until it is needed. Therefore, the pressure of the air is increased. This pressure is used in applying the brake.
There are two kinds of brakes in such vehicles. One is the parking brake, and the other is the service brake. The parking brake is used for keeping the vehicle securely in the state of rest. So it is basically used to hold the vehicle. The service brake is used for gradually slowing down the vehicle, thus bringing it to rest.
Now, when the brake pedal is pressed by the driver, the air stored in the storage tanks is released and thus the pressure of the air applies the service brake. This pressure also releases the parking brake at the same time.

Note
The hydraulic brakes are used in medium weighing vehicles such as cars, aeroplanes, cranes etc. But in the heavy automobiles, which carry tonnes of weight over large distances, the hydraulic brakes are not used. This is because the liquid fluid can be lost in a leak. But on the other hand air is abundant in the atmosphere. So in the heavy duty vehicles such as diesel trucks, tractors and buses, air brakes are used, in which compressed air is used instead of liquid.