News0 min ago
Bus noise
Why does a bus make a hissing noise when it comes to a stop at a bus stop?
Answers
1 to 2 of 2
Best Answer
No best answer has yet been selected by Mudit. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.
As wildwood says, buses, like trucks have air brakes. The air brake chamber(one to each wheel) has a massive spring inside it which is trying to put the brakes on. This is a fail safe. If the air supply goes, the vehicle should stop. So the air acts on a piston which keeps tthe spring compressed and the brakes off. So when you slow down, as you apply the brake a bit of air leaks out. When you come to a stop, you apply the park brake which lets all the air out and it goes 'Tssschh' (or something similar!).
1 to 2 of 2
