The watch barrel, a crucial but often overlooked part of mechanical and automatic watches, has a rich history that has brought it to its modern state. While older versions functioned, they also had a number of problems that have since been solved by watchmakers.
Read on to learn about how the watch barrel has evolved through history:
A watch barrel is the cylindrical drum, or box, in a watch that contains the mainspring. But the watch barrel is more than just a case—it acts as the first gear in the watch’s train.
A watch barrel has toothed gears on the outside edge that mesh with the movement gear trains. Once wound, the mainspring naturally tries to regain its original shape by uncoiling. The watch barrel rotates as the spring uncoils, and then the once stored energy is transmitted to the oscillating balance through the wheeltrain and escapement.
Watchmakers have paid much attention to this watch component throughout the history of watchmaking. Ever since spring-driven watches hit the market, they have been trying to find the best watch design to encase their movements.
The plain watch barrel is the easiest solution. To create a plain watch barrel, watchmakers fasten one end of the mainspring to a post and the other end of the spring to a barrel with a gear attached to it. They then wind up the spring by turning the barrel, thereby tightening up the spring around the center post. When the watch runs, the gear turns slowly the other way.
While the plain watch barrel is simple, it also presents 3 problems:
- While the watch is being wound, there is no power to keep the gears turning; you lose time every time you wind the watch.
- When the spring is fully wound, it pushes the gears much harder than when it is wound down.
- If the spring breaks, it will whip around and slam against the barrel. This will cause the barrel to turn in the opposite direction than it should, which can damage gear teeth, break jewels and cause other damage.
Watches made with plain barrels disappeared before 1850 because of these problems.
In response to the problems encountered with the plain watch barrel, watchmakers invented the fusee, a cone-like device, which they attached the spring barrel to with a tiny chain.
When the spring was fully wound, the chain was mostly wound around the fusee. As a watch ran, the chain unwound from the fusee and wrapped around the spring barrel. Mechanically, the chain was the weakest when fully wound and strongest when unwound; this meant that a nearly constant force was applied to the gear train, unlike the uneven force issue with the plain watch barrel.
The fusee also solved the problem of the barrel whipping around and damaging the watch, but not the inability of the plain watch barrel to maintain power while being wound. Additionally, the fusee took up a lot of space and also increased the watch’s cost.
The Barrel and Fusee system was predominant in English watches until the 1890′s.
The motor watch involves the watchmaker winding the barrel and driving the gear train with the axle, as opposed to with the barrel. Then, if the mainspring breaks, the damage is absorbed by the gears, which are easily strong enough to handle it.
While the motor barrel also can use a weaker mainspring, the motor barrel has a lot more parts than a going barrel, whose simple design is chosen by most quality watchmakers today.
Since the 1850′s, most watches have utilized the going watch barrel. The going watch barrel has the center post act as an axle which turns to wind the watch. As the watch unwinds, the outside barrel turns, so tension on the spring always exists.
Additionally, the going barrel solves the issue of damage caused by a broken mainspring with a “safety pinion.” The safety pinion is on the axle and engages the mainspring barrel with tiny threads. These threads tighten in the opposite direction of a usual screw, holding the pinion tight and driving the watch. However, if the mainspring barrel moves the other way (as in the case of a break), the pinion unscrews and disengage from the mainspring barrel. Because the unwinding motion disconnects from the mainspring, the watch is safe from damage.
When debating on spending a few hundred dollars on a new watch, remember that centuries of innovative thought and trial-and-error have gone into just one small part of the watch. The quality of a watch is reflected in the caliber of its parts, and choosing a watch with time-tested engineering means that your investment will last for years.