What are the things that only mechanical engineers know but most people don't?

A professional Engineer covers both side of the physical phenomenon. theoretical and practical which ordinary people do not know

basic fundamentals and also actual work or working principle of the system and machine.

A professional Engineer covers both side  theoretical and practical which ordinary people have only practical knowledge.

We mechanical engineers know about the Geneva Mechanism. Ever wondered how to convert a continuous rotatory motion to an intermittent one? Well, the Geneva drive, or commonly called the Maltese Cross, is all that you need.

INNOVATION  WAS THE MAIN THINGS  OF MECHANICAL ENGINEERING