why do some engine maintenance cycles run off hours, like generators, but others off miles, like cars? (Besides the obvious)

Question

why do some engine maintenance cycles run off hours, like generators, but others off miles, like cars? (Besides the obvious)

In: Engineering

Answer 1

The reason to use miles over hours in cars has less to do with the engine (where the ultimate in metrics for service scheduling would be total rotations of the crankshaft and would be a relatively high number) and more to do with all the other stuff in the car, particularly tires and brakes. Tires only experience significant wear when you’re driving on them, and brakes only experience significant wear when you’re driving and have to stop.

You might be able to go longer without some services if you counted hours or revs of the crankshaft, but having one metric to base all your different services around is an easier system.