Training Movement: Lemania 1873

The training wheels are off, and we're starting to tear into some really interesting training movements.

The Lemania 1873 is a classically-designed lateral-clutch chronograph, and while it uses a cam instead of a column wheel, it is a good base to teach traditional chronograph adjustments.

Lateral chronograph clutch systems use a driving wheel (left) which runs off the fourth wheel pivot, and constantly meshes with the clutch wheel (top). The clutch wheel is attached to a large lever which pivots near the escape wheel and reaches all the way to the cam. The lever pivots the clutch wheel into and out of engagement with the chrono runner (right) to start and stop the chronograph.

Notice that the clutch wheel and the chrono runner both have triangular teeth. This is a sub-optimal tooth profile for power delivery, but it ensures smoother and (relatively) jitter-free engagement of the chronograph seconds hand. Since the clutch wheel is always running, it may not be perfectly aligned to the chrono runner when they come into contact, so the chrono runner has doubly-fine teeth to reduce the error. Regardless, the chronograph seconds hand will have some jitter when started, but that can only be totally eliminated with a different mechanism.

This is an exciting movement to work on, and requires significant care to assemble and lubricate properly. We'll be training on this for a while, and then will move on to even more complicated things!