Re: Timing tutorial?

An interesting note on this topic is the fatigue of the bearings for an engine that is out of square and an engine that is in square;

A locomotive that runs "in square" should be even in both strokes; i.e. the valve admits the same amount of steam to a power stroke in each direction. Out of time locomotives do not accomplish this, which is why the "chuffs" are not even in spacing or volume in some cases.

What this means is that a locomotive in square undergoes (approximately) fully reversed loading, which means the the mean stress in components is zero (the force exerted on bearings, rods, etc goes from +some value to -some value), which means the fatigue analysis of the materials is simple and much likely to have long component life.

A locomotive out of square would have a non-zero mean stress, which would decrease the life of components significantly depending on how large the mean stress is.

Mark Huber
Hyce on YouTube