How does engine hour meter works?

Question

How does engine hour meter works?

Answer 1

Varies wildly. Some are simple clocks mechanically driven, dependant on engine rotation. Some are electronic timers, driven from the alternator or ignition systems.

Answer 2

the hour meter is connected to the tachometer i.e the rpm meter and hence it calculates the working hour of the engine. if it is a mid to high end engine that will be calculated by timer chips electronically which will be more accurate.