Power Reserve.... What Is It.... ?? (my views)

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Originally Posted by dubeagle

Great info.

I read somewhere that as the mainspring is tighter (or more) wound, the watch slows down and that as the reserve is reduced, that the watch speeds up. Can this be?

Yes... that tends to be true..

A tight mainspring provides maximum pull to the gear train so you have maximum friction, and you have a pallet yoke that has a stronger "push" on the hairspring jewel to give maximum amplitude to the hairspring....maximum amplitude means that it is swinging back and forth at about 300 degree arcs.. it is the timing and speed of this swing that locks and unlocks the escapement wheel....tick-tock, at exactly 8 per second.

When the mainspring winds down, there is less torque in the system, less friction, and the hairspring does not get quite as big a "push" from the system..the amplitude drops to less than 240 degrees per swing (swings shorter and faster), there by speeding up when the mainspring is unwound.. perhaps 8 1/2 to 10 ticks per second..

(There are other forces as well, but this is a key point)