How the mesmerizing tourbillon and carrousel work

A tourbillon movement works exactly like a traditional mechanical movement would.

The only difference from a traditional movement is that the assembly of the regulatory organ of the watch, that is, the balance wheel, rotates around itself, eccentrically on its cage in a proper tourbillon, or axially in a carrousel system (both work following the same principle, though – that is, making the balance wheel and its assembly rotate on their axis).

The traditional movement of a mechanical watch has a point-to-point distribution system. That is, the mainspring imparts energy to the watch movements, which is used to make the balance wheel oscillate back and forth. You can check it in this old Rolex movement: the balance wheel, on the bottom of the image, is held in its place by a bridge. Its 270° of oscillation happen always on the same axis.

A Rolex-made mechanical movement of a vintage Panerai.

his oscillation – which has a median amplitude of 270° – happens only in one axis, or as horologists say, “position”. This means that it could be subject to recurring errors depending on the position that the watch assumes.

The inventor of the tourbillon: Breguet

The inventor of tourbillons, Mr. Breguet, knew that this was the case.

Pocket watches (as in the beginning of the 1800s there were pocket watches only) had only two main positions in which they were used: a vertical carrying position, when they were worn and put in pockets, especially a waistcoat’s; and a horizontal position, when they were put on a table, face up, to let people work (write letters, have meetings and such).

This meant that the mechanisms could have been subject to tiny errors which would stack up in time. And one of the best solutions was to “average” this errors so to neutralize them. If the balance wheel rotates around itself every minute, the errors that it would get when it is at a 0° angle would be averaged by the error it gets at a 180° angle.

This was right, especially if we consider pocket watches, which was the case in the beginning of the 1800s.

So, Mr. Breguet developed and patented a system to let the balance wheels rotate around its axis to reduce this error in timekeeping as possible.

He achieved that by mounting the balance wheel, pallet and escapement, in a rotating cage. The rotation (which generally takes one minute to happen) was enough to ensure that the oscillations happened in different positions.

A tourbillon watch made by Guinand for Girard Perregaux

The assembly above, even if it isn’t so evident, groups together the last three elements of the watch works: the escapement wheel, the pallet, and the balance wheel.

Imagine them as if they were contained inside a cage that rotates on itself.

The system mounted inside the cage of a tourbillon: balance, pallet and escapement

As you might argue, this was perfectly logical in a pocket watch, but has much less sense in a wristwatch. Today, we wear watches on our wrist. This means that the position where a balance wheel operates constantly shifts, depending on the position of our arm, so the effect of a tourbillon would be lessened.

This is to say that our modern wristwatches are more precise vs. old pocket watches because we wear them on our wrist. The continual change of position makes them operate as they were using a tourbillon-based system.

However, there is one more thing to notice. Tourbillon systems are extremely appealing to watch.

The constant movement of the balance wheel in the tourbillon cage has a mesmerizing effect. This explains the increasing success of tourbillon watches from the Eighties onwards, when they have been re-discovered and relaunched.

Flatly said, currently a tourbillon is not really that effective. There are much better ways used to achieve good timekeeping performances than through a tourbillon.

A tourbillon watch by Hermès

However, tourbillons look extremely good, and any watch lover – or almost – would love to get one around his/her wrist. Even if it’s nowadays almost useless.

You can find much more about horology and its fascinating history in The Watch Manual, a thorough e-book that explains all the basics about watchmaking and its protagonists.

To download a FREE 8-chapter extract from The Watch Manual







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