Your Bag

Nothing in cart

How Do Mechanical Watches Work? Scrutinizing The Inner Parts

How Do Mechanical Watches Work? Scrutinizing The Inner Parts

Mar 12, 2024

Wondering how mechanical watches work was the first thing I found complicated about a watch. It was getting more confusing to know a watch that does not need batteries to run. I didn’t exactly understand how the intricate parts in it make the time sweeps only with the process of winding.

But as time goes by it is just a matter of time until you are curious about other things. Enjoying how those components work harmoniously together to be a reliable watch is truly a moment of art. So, while you are still here, let’s talk more about how mechanical watches work.   

What is A Mechanical Watch?

There are two common types of watches. The one that uses batteries or known as quartz watches and battery-free timepieces or mechanical watches. So, how accurate are mechanical watches? Considering the technology used in quartz movement, mechanical watches are less accurate.

However, the craftsmanship of a mechanical watch is undeniable since it uses a mechanical mechanism to measure time. That is what makes a mechanical timepiece a product of art. Furthermore, mechanical watches need much more labor-intensive to build, resulting in a far more expensive watch than quartz watches.  

A mechanical watch uses a mainspring that needs regular winding. The power that sweeps the hands across the dial and controls further complexities, such as a date function, a moon phase, or a chronograph, derives from the unwinding mainspring, which also rotates the gears at various speeds. This process allows the wristwatch to tell time. A mechanical watch particularly depends on how the process of winding would operate every element in the watch. 

So, how long do mechanical watches last after we wind them? Once again, it is on the mainspring. The longer the spring, the longer it will run. We call this a power reserve or the remaining energy in the mainspring. To help you picture the whole process, we have provided you with a simpler explanation of how mechanical watches work.

See also: Scrutinizing Watch Movement Types and How They Work

How Does A Mechanical Watch Work?

Understanding how mechanical watches work can be quite overwhelming, especially if you are a newcomer to mechanical timepieces. There are intricate parts in the movements that work together in harmony and every part has its own function. To help you better understand how mechanical watches work. Let's first scrutinize each part.

The crown: set and wind the watch

The crown is connected with the inner parts, such as the setting jumper, gears, pinion, setting lever, and yoke. When you pull out the crown to set the time, the setting jumper locks the crown mechanism. That way, it won’t be pushed in easily with its indents.

The other elements, such as the lever will do their work to make the yoke move. It makes the sliding pinion into connection with the gears that spin the watch hands. When the crown is pushed in for winding, the gears connected to the mainspring are turned by the sliding pinion. From here, the watch can run smoothly. 

The mainspring: the watch’s energy

A mainspring is a flat hardened metal that is coiled into a spring. This element determines how long the power reserve of a watch is. It serves two important functions which are providing power energy for the watch and ensuring precision.

The mainspring is placed in a mainspring barrel that is connected to the winding pinion. It's also connected with another barrel located under the mainspring barrel. In short, the mainspring is the powerplant and by winding the spring, the energy can be stored in the mainspring. 

See also: Watch 101: A Special Highlight for the Watch Mainspring

The wheel train

The wheel train drives time-keeping hands and associated wheels. The center wheel is driven by the mainspring barrel and rotates once per hour. It holds the minute hand, and its 60-minute journey is often divided up into minute marks on the watch face.

The third wheel flows power through the fourth wheel. The fourth wheel rotates once per minute in incremental ticks and holds the seconds hand. Again, marks on the watch face can make it easier to see how many seconds have passed within one full minute-long revolution.

The motion works

The motion works allow the watch hands to be freely rotated for time setting and also perform a 12 to 1 speed reduction for the hour hand. Since the center wheel and minute hand rotate once per hour, the hour hand needs to make a much slower journey, completing a full rotation once every 12 hours.

In simple words, the motion works is another form that transcribes the process of unwinding the mainspring, gears rotation, and the wheel escapement action into meaningful information for a time-teller.

The escapement and the balance wheel

The balance wheel swings in a precise rhythm, knocking the pallet fork back and forth and allowing the escape wheel to move which releases mainspring power in small metered increments. This particular part, however, is the most fragile one. Therefore, it is supported by a shock-absorbent mounting system with a jewel bearing and capstone that protects the sensitive parts from any harm, such as if the watch is dropped. 

Driven by the hairspring, the balance wheel impulse pin bumps into one side of the pallet fork, releasing the opposing pallet jewel from a locked position against an escape wheel tooth. Just as the pallet jewel slips free, the specially shaped escape wheel tooth delivers a little impulse of power from the mainspring through the pallet fork, which in turn pushes the impulse pin, launching the balance wheel into another swing. And so the process repeats as long as the watch has mainspring power.

The hairspring has regulator pins to adjust the active length of the spring. This alters the balance wheel swing rate and as such, the speed of the entire wristwatch. This is what is meant by regulating a watch that keeps time too fast or too slow. Usually, a watch's beat rate is 21,600 beats per hour which equal 6 beats per second.

See also: Watch 101: What is the Balance Springs for Watches?

Supporting structure

Various specially shaped metal plates support watch internals. The main plate serves as the base while the barrel bridge holds the mainspring barrel and associated parts. The train wheel bridge supports the wheel train and the pallet bridge holds the pallet fork. To support the balance wheel and regulator assembly, the balance bridge is there.

How do they work together?

The way mechanical watches work is indeed as complicated as it seems. Several parts are working together in perfect harmony to make a watch move. But if every part is put in a line to see how it works, the process becomes more apparent and easier to be understood.

Let’s keep in mind that the mainspring is the source of energy for a watch. Then, moving on from this power source, inside a mechanical watch also lies a system that controls the flow of the power called the balance wheel and hairspring assembly. They also contain several parts, the balance wheel and hairspring itself, the balance staff or axle, a roller, and a jewel.  

Talking about the balance wheel as only one individual part, a push on the jewel pin will make the balance wheel starts moving. The one that does the job of pushing is called a pallet. It can be mounted so that when the pallet moves forth and back, it will create a series of impulses to keep the balance wheel in motion.

In addition to that, a pallet jewel is also added to the pallet cross arm. Here, another part named an escape wheel is connected to the pallet jewel. An escape wheel has teeth-shaped around it to push the pallet jewel and, thus, jog the balance wheel to keep moving.

However, when the mainspring drives the escape wheel, there isn’t a way to hold the power in check. As the mainspring on coils, it causes the barrel to rotate with it and that wouldn't last long. Therefore, another pallet jewel is put at the other end of the pallet cross arm to ensure the power from the mainspring is released a little at a time just when it's needed.

Just as the first pallet jewel gets a push from the escape wheel, the second pallet jewel locks against another tooth of the escape wheel to hold the power of the mainspring in check. But at that same moment, the balance wheel keeps moving and the jewel pin moves the fork end of the pallet until the escape wheel is again unlocked.

But still, the power from the mainspring will be soon exhausted if the escape wheel is directly connected to the mainspring. In fact, that whole process would only last for a few seconds in an actual watch. A way to stretch the power is needed so that the power would last for more than a day. That’s when the wheel train comes to the rescue to transfer the power from the mainspring to the escapement wheel. 

A small turning of the mainspring barrel will move the center wheel in a complete revolution. Meanwhile, a partial turning of the center wheel will drive the third wheel in a complete revolution. This, in turn, will create a much further motion for the fourth wheel. These integrated processes that create turns driven by the mainspring will make many revolutions in the escape wheel, enough to last a full day and even longer. That’s when you see a movement on your watch dial

Final thought

Now that I know every part that makes a mechanical watch work, a high appreciation should be given to the watchmakers. With all of the intricate and delicate things behind a watch caseback -- a beautiful process from winding the crown until the mainspring energy is released to the balance wheel -- it's a wonder how these contraptions could provide a precise time-teller. Not to mention if the watch comes with a range of complications that certainly will add complexity to the process.

With all of that being said, there is one thing that should not be forgotten about mechanical watches. Friction and external shocks are the main problem in a mechanical watch that the wearer should pay the most attention to. Therefore, proper maintenance is essential for a mechanical watch to last a lifetime.

You might also like: The Top 6 Invaluable Grail Watches for Your Watch Collection

You may like this

Related Articles

Comparison Chart

No watches in comparison chart

Artboard 1
Artboard 1



Lug width

Water resistance


Lug Width
Water resistance