Belts are one of the most ubiquitous clothing items and as such are often simply taken for granted. Documentation exists at least since the early Bronze Age, though it is likely the belt has been in use for much longer. It is, in many regards, the simplest and most functional strip of material a person can have.

Worn on and off throughout the centuries for fashion reasons, belts have always held a very functional role. A belt tied around the waist can cinch up a tunic or robe nicely, plus provide a place to tie additional accessories such as a bag, money pouch, or even small bundles of goods.

Samurai with a tachi sword in his belt

Then there is, of course, the ability to hold a dagger, dirk, katana, saber, rapier or any other small- to medium-sized blade for defense . .  . or even thievery. Belts have almost always been employed for assisting in that as well.

Mantua dress with blue belt

Aside from the early Middle Ages and seventeenth-century mantua (women’s dresses), belts have usually been much more common with men, though they have a strong history with both genders, especially in more ancient times.

Today, the belt has a firmly entrenched position as a male clothing requirement (at least for “properly” dressed individuals), and an optional fashion accessory for females or the sartorially daring.

Sadly, we have also lived to witness the rise of the belt clip cell phone holder, probably the most misguided attempt at helping those individuals who lamented the passing of the once-popular pager. Despite that black mark on the belt’s record, it still stands as one of the most functional and handy things to have on your person.

Depending on material, the belt can also serve other purposes with examples of it being used as a tourniquet, tie-down, medical sling, and in the rare case that it is made of braided paracord (nylon kern mantle parachute cord), it can even serve as survival rope.

A functional mechanical tool

The belt can be a lifesaver for fashion or an adventurer’s folly. It also happens to be one of the most functional mechanical tools mankind has invented beside the wheel. Actually, the belt was invented to make full use of the wheel.

A belt can be used to drive machinery or pumping a piston in the form of a belt and pulley.

Flat belts are the oldest versions, even being used to power machinists’ lathes well into the twentieth century. This type of belt drive has lasted so long because it could be used to power shafts that weren’t aligned, would protect against overloading or jamming, and prevented shocks from destroying the other end of the mechanism.

This is true of any belt-drive system, with the flat belt version being the simplest and most straightforward to make and maintain.

Extensive conveyor belt system moving sulfur in Canada

Belts have also been used as means of moving large amounts of material continuously from one place to another as a conveyor belt. These forms have revolutionized production and manufacturing all over the world and helped to create the modern assembly line.

Liebherr bulldozer

Oh, and if you take an assembly line and flip it over, you can use the conveyor belt to move the machine, in the form of a belt track like what you would find on a tank or bulldozer.

Given all of that, the most common way you will interact with a mechanical belt will probably be with your car or truck and the timing and serpentine belt connected to the engine. These belts, usually grooved or toothed, help to keep engine components spinning in sync with each other and allow them all to be powered off the rotational motion of the crankshaft.

The belt is a beautifully simple system that, with proper maintenance, can last as long as or longer than you may own the vehicle. What an increditastic invention the belt is, if I do say.

A specific role within this watch

As you can see, the humble belt, a simple strip of fabric, leather, rubber, or rope, has a long and full history with thousands of iterations and as many uses. It is considered a primary component of the pulley and one of the six “simple machines” defined by Renaissance scientists.

It also happens to be something that has a very specific role in the new TAG Heuer Monaco V4 Tourbillon, that role being to transfer power from the mainspring barrels to the gear train and from the gear train to the delicate tourbillon mechanism.

TAG Heuer Monaco V4 with black case

It all started in 2004 when TAG Heuer first released the Monaco V4, the first watch to be driven by belts instead of the conventional wheel and pinion. After ten years of experimentation and redesigns, the Monaco V4 Tourbillon was released in 2014 to much fanfare (I mean fanfare literaly, I was lucky enough to attend the launch party at Baselworld, and it was a spectacle for sure).

The V4 has always held a special place in my heart, and with the release of the newly designed movement specifically for the V4 Tourbillon I wanted to break down why it is incredible, why it is intensely difficult to engineer, and why I applaud the efforts and the final result.

The automatic winding function starts things off with a bang. A linear weight made of tungsten holds two toothed racks that mesh with two sets of mainsprings inclined at 13 degrees, forming the eponymous V of the V4. The four stands for the four mainspring barrels connected in a series by two belts (we’ll get to those later).

These mainsprings are mounted on micro ball bearings instead of the standard jeweled pivots and are cantilevered out from the movement, i.e. held only on one side. This creates a very clean and engine-like rear of the piece.

But this really isn’t why we are here now, is it? Nope.

Tag Heuer Monaco V4 Tourbillon

What are polyamides?

Polyamides. This is what the tiny little belts are made out of, and that probably doesn’t mean much to anybody but chemistry or material science nerds. A polyamide is a macromolecule with repeating units linked by amide bonds. Yeah, doesn’t make much sense, does it?

Basically, it is a plastic-like material that can be employed in similar ways to polymers but is chemically rather different and has unique properties that make them much more stable, durable, and strong.

Well-known examples of polyamide types are Nylon, Kevlar, and Nomex.

And yet those unique properties don’t make them any less of a pain in the neck to work with, especially at such miniature sizes. While chemically stable, it does not mean that they do not have certain physical and thermal properties that are magnified when you are working with an individual strand that is only 0.07 mm thick.

And 0.07 mm is the thickness of the smallest belt on the V4 Tourbillon, with the other three only marginally larger. They are so thin that the two connecting the mainspring barrels to the gear train are reinforced with a steel wire to maintain structural integrity.

But the real problem is elasticity. The elastic properties of polyamides vary depending on the type, and also within each individual piece. Of course there is a narrow range based on the chemistry involved, but subtle differences can create a belt that is slightly stronger and less “stretchy”, or one that is slightly softer and too elastic.

For this reason it took eight months of experimentation and development to finally land on three types of material used for the different belts. Based on how they are used within the movement, they require different structural characteristics, and as such the formulas for each one must be fine-tuned.

Skeletonized bridge of the TAG Heuer Monaco V4 Tourbillon

The tourbillon is such a delicate system requiring smooth and precise energy delivery that powering one with a belt proved to be a difficult challenge. Even with building on the knowledge learnt in developing the original Monaco V4, TAG Heuer needed another five years to make the tourbillon version ready commercially,.

The company needed to understand how to make a belt strong, pliable, and stable enough to be used to power the tourbillon. In the end, the defining factor ended up being patience and a large number of extra belts.

Intricate assembly

During assembly of the system, the watchmaker pulls an individual belt from a large pile and carefully joins the pieces together, doing his or her best not to stretch or deform the belt in the process. If it is pulled even a little too hard or twisted a little too much, that belt is considered useless as it has deformed too much to be useful to properly transmit the appropriate amount of energy.

TAG Heuer Monaco V4 Tourbillon

Another belt is then grabbed from the pile and the process begins again. This allows for assurance that once it is assembled it can be closely adjusted and will run flawlessly from then on.

The same properties that allow polyamides to be perfect materials for the belts also make them highly sensitive to handling and incorrect manipulation, which you wouldn’t have to worry about with steel or brass wheels and pinions.

It is also for this reason that I highly admire the chutzpah of the engineers and watchmakers behind the V4 Tourbillon. They were up against a wall for the entire development with the industry saying it wouldn’t work and they were wasting their time.

A waste of time will always be subjective until history has had its say. TAG Heuer decided to develop these things for the same reason John F. Kennedy describes his decisions with regard to going to the moon: “Not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.”

Maybe TAG Heuer never thought it that way, or maybe the company would agree with it, but I for one am reminded of those sentiments when I see such a leap from standard watchmaking technology and a risky attempt at something different.

Close-up of the TAG Heuer Monaco V4 Tourbillon

The Monaco V4 Tourbillon is awesomazing simply because it was attempted, and it seems so far, succeeded.

Regardless of the claims towards tourbillon accuracy or the long-term feasibility of belt-driven movements, the effort, innovation, and sheer audacity of the attempt should be championed. If not for the brand’s sake, then for creativity’s sake, because it is that creativity that helps the next generation realize that new things are possible and they may be the ones to create them.

Naysayers will always be among us, but if we focus on the hope of change over the fear, I think we will be just fine.

Let’s break it down with a little love, peace, and chicken grease.

• Wowza Factor * 8.85 A tourbillon driven by belts in a classic Monaco case, it has watch nerd written all over it.

• Late Night Lust Appeal * 68.25 gn » 669.303m/s2 One and a half times the maximum force for a human rocket sled, this puppy has more than enough force to keep you in your seat until the morning sun comes peeking through the window panes.

• M.G.R. * 67.25 Incredibly strong rating for a daringly cool movement: belts driving a tourbillon. What more do you want?

• Added-Functionitis * N/A Like many of the jaw-dropping pieces I cover, this watch only tells you the time while being as awesome as it can be. So there is no need for Gotta-HAVE-That cream, yet.

• Ouch Outline * 10.44 – Grabbing The Hot Plate The Waitress Just Told You Was Extremely Hot – We all do it, because we think they must be exaggerating. There is no way they can legally serve us something that might hurt us right? But those second-degree burns prove otherwise. But to have the Monaco V4 Tourbillon on my wrist I would gladly grab that plate with both hands and not let go!

• Mermaid Moment * Are Those Tiny Belts!? All it takes is the few moments to realize that the tourbillon is being driven by tiny little timing belts to know that this piece is incredible. Heck, it makes me think I need to start planning the groom’s dinner.

• Awesome Total * 856 The number of components (214) multiplied by the number of micro belts (4) gets you an absolutely respectable total. Two thumbs up.

For more information, please visit www.TAGHeuer.com.

Quick facts
Case: 41 x 41 mm grade 5 titanium with titanium carbide coating
Movement: Caliber V4 Tourbillon
Functions: hours, minutes
Price: 150,000 Swiss francs