SIHH 2019: Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar

Sometimes the most simple ideas eventually lead to the greatest changes. At this years watch fair SIHH 2019, the oldest watch manufacture in the world, Vacheron Constantin surprises with a new power reserve technique that appears to be fairly simple, but is extremely complicated in its mechanical implementation.

Neat crafting – the 480 components fit into a 32 mm case

Complex mechanisms are best explained on practical examples taken from life. Broadly speaking, a mechanical watch works similar to a human or animal organism. To survive, we need ‘fuel’ that our body turns into energy. The mechanical watch transfers the energy that it receives from winding to the barrel. 

In human terms we call it energy reserves, in terms of watches it’s called power reserve that is usually exhausted after a few days. Consequently, if we want to put the watch aside for a while, we need to reset it which is especially time-consuming for watches with complications like Moon Phases or Perpetual Calendars that should only be adjusted by a watch maker really. A Perpetual Calendar only runs perpetual when it runs continuously.

A maximum of 65 days power reserve in Standby mode

Until now, a watch mover assisted in periods of rest. The engineers at Vacheron Constantin for the first time breathe an extended and independent life into a watch with the new Traditionnelle Twin Beat Perpetual Calendar, without needing to ‘feed’ it in between. The trick: a second balance that was designed for the Standby mode and offers a power reserve of 65 days. The power reserve for the Active mode lasts for four days approximately.

Two balances with different frequencies for Standby and Active mode

Back to nature: certain animals, just like bears go to hibernation or dormancy (as bears only rest at times) in the winter months due to food shortage. The challenge is, that the body needs to carry on functioning without new supplies of energy. Therefore the body reduces its heart rate and activates its reserves. If you want to put the new watch with the patented Twin Beat mechanism away for a longer period, you can activate the second balance by a dedicated pusher that brings down its frequency from 5 Hz (36.000 vph) to a mere 1.2 Hz (8.640 vph). To adopt this to the human or animal organism it would mean an alarming low blood pressure – the lowest frequency used in watch making is normally 2.5 Hz.

A separate pointer on the dial indicates the current frequency

Vacheron Constantin has developed a hairspring that is nearly four times smaller and hence more delicate than the hairspring of the Active balance. With an ingenious construction, they are able to marginally impact the chronometry (about 8 minutes deviation in 8 weeks) even with a lower torque. The only requirement is that the watch is not worn and needs to be put flat on its backside to reduce the impact of gravitation on the mechanism. 

The barrel with its gear-differentials (left)

The patented sprung dual-gear compound system for the date settings of the Perpetual Calendar (right)

Both balances are linked to the barrel by two separate gear trains. The hour and minute hands have to draw variable information from two gears but still run constantly and reliably. A gear differential that is mounted onto the barrel controls the energy source that at this very moment is responsible for the timekeeping. A mode selector takes care that only one balance oscillates at a time and that the switch occurs without interruption. A second differential mounted on top of the barrel is linked to the main hairspring and takes care that the torque is reduced in Standby mode. 

The barrel with its two balances (left)

The differential for the double-power-reserve indication (middle)

The balance that needs to be in action is adjusted by a separate lever (right)

Like the movement doesn’t already have enough work to keep the standard timekeeping alive for 65 days, Vacheron Constantin has given it a side job and also integrated a Perpetual Calendar with an instant jumping system. That means that the display elements (day, month, year) move along in a jumping manner, which takes up a lot of energy. If a bear is awakened ungently from his winter rest, his body will mobilize all reserves to cover the rapid upswing of energy consumption. The energy requirements for the instant jumping display of the Perpetual Calendar cut into the energy going towards the balance and in many cases, the balance loses amplitude that affects the chronometry of the entire movement.

Extremely innovative:
the Twin Beat Perpetual Calendar with an instant jumping system from Vacheron Constantin

To avoid this, Vacheron Constantin has developed a jumping mechanism that continuously accumulates and saves energy over time. A special sprung dual-gear compound system requires four times less torque than a conventional jumping display. With this, the movement is able to master the energy-absorbing jumping of all three displays of the Perpetual Calendar at the turn of the year even in standby mode. 

All functions at a glance

The still young calibre 3610 QP is gently bedded in a classical case design of the ‘Traditionnelle’ collection and made of platinum. Movement plates and bridges are decorated with Côtes de Genève and treated with NAC that ensures more durability. The upper dial part has a radial hand guillochage and sand-blasted surfaces. On the lower part, the Perpetual Calendar switchgear mechanism flashes very atmospherically from underneath the edge of the partly opened dial. 

Calibre 3610 QP

The calibre 3610 QP consists of 480 components measuring only 6 mm height in a mere 32 mm case diameter, which is extremely slender for a Perpetual Calendar watch. The Traditionnelle Twin Beat Perpetual Calendar costs 217.000 Euros and is not officially limited, however the manufacture will most likely only produce a minor number of pieces per year. 

The new Twin Beat has a platinum case and costs 217.000 Euros

www.vacheron-constantin.com