eli5 Why do trucks and busses do the “tsshhh” thing when they stop?

Question

eli5 Why do trucks and busses do the “tsshhh” thing when they stop?

In: Engineering

Answer 1

A lot of Buses also use air suspension too, but of course this hissing sound you’ll only hear when the bus stops, usually to let ya grandma on or someone with a wheelchair for example.