Before the arrival of battery-operated quartz watches, the standard timepiece was mechanical.
When exploring the realm of timepieces, it’s fascinating to delve into the intricate world of mechanical watches. Within this realm, we encounter two fundamental categories. On one hand, there are manual watches, which demand the deliberate act of winding to keep ticking with precision. On the other hand, automatic watches seamlessly intertwine with the wearer’s everyday arm motions, eliminating the need for manual winding. This dual nature of timekeeping devices adds a captivating layer to the broader discussion of horology, making it an intriguing subject for those who appreciate the finer nuances of watch craftsmanship and, in turn, sparking curiosity for insightful watch reviews.
In either case, the part being wound is the mainspring. So it makes sense to begin our discussion of a watch’s inner mechanisms there.
The mainspring is the key source of the mechanical watch’s power. The mainspring is an s-shaped torsion spring stored inside a container known as a barrel. To increase the potential energy of the spring, it needs to be wound.
When the tension is released, the spring attempts to return to its natural state. It then forces the barrel to rotate on its axis. It’s that motion that will power the entire watch.
However, under normal conditions, the spring unwinds too quickly for a watch to harness its power for accurate timekeeping. In other words, the barrel would rotate at too high a speed.
What’s needed is a way to use the mainspring in the barrel to rotate the hands, especially the second hand, many times per each revolution of the barrel. The watch also needs to control the spring’s power by slowing down its release.
A series of connected gears form the watch’s gear train. By careful selection of the gear’s size and configuration of teeth, a watchmaker can more precisely establish the rotation of the hands.
However, there’s still the overall speed of the mainspring that needs to be considered. How can a watchmaker slow it down?
The escapement is the combination of a special gear called an escape wheel and a pallet fork. As the mainspring unwinds it turns the escape wheel.
If there were no speed control, the escape wheel would be at the mercy of the unwinding mainspring. So watchmakers use a pallet fork to routinely interrupt the turning of the escape wheel.
The pallet fork stops the escape wheel briefly, releases it momentarily, then repeats the cycle by stopping it again. The pallet fork’s movement is smooth, rhythmic, and predictable. It’s the pallet fork’s interaction with the escape wheel that creates a mechanical watch’s familiar tick-tock sound.
But what controls the pallet fork?
A watch’s balance is the balance wheel and the balance spring. As the balance wheel swings, it disrupts the pallet fork’s engagement with the escape wheel, allowing the escape wheel to rotate.
Then the escape wheel uses the energy it gains from the mainspring to push back against the pallet fork. The pallet fork, in turn, then strikes the balance wheel, making it swing.
Once the balance wheel has swung as far as it can in one direction, it swings in the opposite direction. The return of the balance wheel then again frees the pallet fork.
Common Mechanical Watch Problems
Manually wound watches should be wound carefully. You want to stop once you feel resistance. Winding too much can damage the mainspring and necessitate professional repair.
Mechanical watches also need occasional recalibration to make them more accurate. The work requires experience and specialized equipment that only a watch repair shop will have.