Jacob Kretz | Automatic | 1810 | Gold
Series: GRAND COMPLICATIONS
By: Sílvio Pereira
Movement of the oscillating weight
Functions:
- Hours
- Minutes
- Date
- Automatic winding
Technical data:
- Lépine-type pocket watch. Automatic winding. Dated 1810
- Functions: Hours, minutes and central date. Automatic winding.
- Serial number: 21
- Maker: Jacob Kretz
- Country - Germany
- Calibre: Full-plate (double plate) layout
- Movement protection: None
- Escapement type: Swiss lever
- Balance: Nickel, with flat hairspring
- Power reserve: 36 hours
- Frequency: 18,000 vph
- Jewels: 15
- Case material: 14 kt gold.
- Dial: enamel, with no flaws or hairlines
- Small seconds: None
- Case diameter: 52.1 mm
- Thickness: 22.8 mm
- Weight: 107.47 g
- The mainspring is wound by the oscillating weight.
- Hands: Louis XV-style hours and minutes
- Numerals: Roman for the hours. Arabic for the 5-minute intervals and indexes for the rest
- Seconds: None.
- Crystal: In excellent condition.
- Case-back numbering: 21
Overall assessment - Automatic watch with date in an excellent state of preservation.
Jacob Kretz
Taking up Breguet's idea of using an oscillating weight to rewind the watch's mainspring, the German watchmaker Jacob Kretz, in the early 19th century, created his own automatic system for powering the watch mechanism.
There is very little information about this watchmaker; all that could be established is the period in which he was active, which was between the end of the 18th century and the beginning of the 19th. This information was obtained from a book that is essential for every collector, “Watchmakers and Clockmakers of the World" by Brian Loomes
After extensive research it was not possible to find any other automatic watch by this watchmaker, so it can be concluded, with some degree of certainty, that the one in the collection is the only one in existence, or one of the few that have come down to us.
The value of the watch rests on its rarity and on the automatic winding complication, this being the first watchmaker, after Perrelet and Breguet, to make watches with this type of complication.
Loehr | Automatic | Power reserve | 1880 | Silver
Movement of the oscillating weight
Functions:
- Hours
- Minutes
- Power reserve
- Automatic winding
Technical data
- Lépine-type pocket watch. "perpétuale" automatic winding and power reserve. Dated 1880
- Functions: Manual and automatic winding, hours, minutes, seconds and power reserve.
- Serial number: 4470
- Maker: Loehr
- Country - Switzerland
- Calibre: Classic bridge layout
- Movement protection: Silver dust cover
- Escapement type: Swiss lever
- Balance: Nickel, with flat hairspring
- Power reserve: 36 hours
- Frequency: 18,000 vph
- Jewels: 15
- Case material: Silver.
- Dial: enamel, with two hairlines at 9 o'clock
- Small seconds: At 6 o'clock
- Power reserve at 3 o'clock
- Case diameter: 47.7 mm
- Thickness: 16.7 mm
- Weight: 84.80 g
- The mainspring is wound by key and by the oscillating weight.
- Hands: Stylised hours and minutes
- Numerals: Roman for the hours. Indexes for the minutes. Arabic for the 5-second intervals and indexes for the rest
- Crystal: In excellent condition.
- Case-back numbering: 4470
Overall assessment - Automatic watch with power reserve in a very good state of preservation.
Loehr Patent Perpetual, Switzerland 1880
Loehr Patent No. 3357
The relationship between precision mechanics and gravity has been explored by inventors and watchmakers since ancient times, beginning with the weights and pendulums of large clocks and ending with automatic winding devices and high-precision tourbillons.
In this article we will examine another watch with a mechanism very similar to that of the model above, equally rare, which incorporates an automatic winding mechanism of an early pendulum design, the 'Perpetuelle'. We will tell the story of this automatic winding mechanism a little further down.
The Von Loehr Patent
The creator of this particular watch movement is the Austrian engineer Von Loehr, who designed a special automatic winding device in 1875 and patented it on 10 January 1878. The patent claimed protection for 11 schemes of mechanisms that convert the motion of an oscillating weight into the tension of a mainspring.
August von Loehr's son, August Ritter von Loehr, was a numismatist and monetary historian who was involved in defending Austria's cultural collections as part of his role at the Federal Monuments Office in Austria. From the known documentation, it seems that he did not continue his father's watchmaking business.
Diagrams of devices from Von Loehr's patent, which automatically wind the spring from the vibrations of the weight.
The main idea is that the oscillating weight is suspended by a spring, as close as possible to the point of equilibrium. The oscillation of the weight forces the winding wheel to turn, interacting with two movable pawls – a pushing one (fixed to the weight) and a holding one (fixed to the body).
The whole design, with all 11 schemes, was patented for general use. However, one of the devices (number 11 in the diagram) was successfully implemented for use in pocket watches, leading to the production of these watches being established in Switzerland in the 1880s, using only one of the devices patented by Loehr.
The dust cover bears the signature Patent Perpetual and the serial number 3357. Note the device on the central arbor, an early design for keyless hand-setting, carried out by fitting a small handle into that opening and then turning. Also worthy of note is the shape of the pendant ring, by which the watch is held upright in the pocket.
Two views of the mechanism
When the watch is carried upright in the pocket, helped by the specially shaped ring, the oscillations of the heavy pendulum wind a spring. The mechanism uses a steel ratchet wheel that interacts with two movable pawls – a pushing one (fixed to a hammer) and a locking one. The teeth of the ratchet wheel are very small and the mechanism reacts even to the slightest vibrations of the pendulum.
The shape of the oscillating weight is very similar to the one created by Abraham-Louis Breguet, between 1775 and 1778.
How automatic winding works in a pocket watch
The pendulum in its two extreme positions
Inside the pocket, the pendulum carrying the weight swings up and down under its own weight. Any slight movement of the pendulum makes the steel ratchet wheel turn by several teeth and stop when it strikes a limiting post; inside the barrel, the mainspring is wound through a system of transmission wheels.
Each swing of the pendulum transmits a sufficiently large force, which turns the wheel train through many dozens of rotations. To see this function in real time, watch the video below.
Additional features and complications
When winding the watch with a key, the user will feel the spring stop and will therefore stop turning it, to avoid any damage. With automatic watches it is more difficult; since these are pocket watches, care must be taken over the safety of the winding mechanism.
To remedy this, there is one more interesting design trick in the mechanism, also patented by Von Loehr. This is a mainspring winding limiter, which protects the parts of the mechanism against damage in the event of overwinding.
An ingenious winding limiter mounted on the barrel.
The limiter is made in a very interesting way; its purpose or operating principle cannot easily be guessed. There is a slot in the cover of the mainspring barrel. A special hook is attached to the outer coil of the spring (indicated by a blue arrow). On the barrel arbor, a toothed wheel is mounted with a fixed bar and a pin at its end, which is raised by about 1 mm (the pin is indicated by a red arrow).
The stop pin comes out from under the plate of the mechanism and can move the locking pawl of the ratchet wheel.
The pin that blocks the winding of the spring.
Until the spring is wound up to the limiter, the wheel with the stop pin swings freely on the barrel arbor. When the spring is wound to the limit, its outer coil moves towards the barrel arbor and the tooth attached to the coil catches on the wheel. In turn, the wheel moves the bar with the pin, and the pin lifts the locking pawl of the ratchet wheel, which is why it stops holding the mainspring.
Even when the spring is wound to its limit, the pendulum still swings, but the forces are not transmitted to the winding wheel train. This solution is competent and interesting, because if the movement of the pendulum were blocked, the limiter could simply break under the weight and motion of the pendulum.
The keyless hand-setting mechanism
It would be impractical to use a key to set the hands of a watch. Therefore, a toothed transfer handle is provided on the central arbor and a slot is made for it in the inner cover of the watch. With a simple movement of the finger, the hands can easily be moved without using a key or a crown. This design has existed since the 1830s, but is quite rare.
The watch was made around 1880, before the mass spread of watch crowns. This is also evidenced by the serial number, as well as by the early design. Later, Loehr Patent watches were fitted with a power reserve indicator and were made predominantly in a square shape, which gave them an additional unique quality compared with ordinary watches.
Features
Nickel case with opening front cover, signed Patent Perpetual #3357.
Enamel dial with Roman numerals and small seconds sub-dial, signed LOEHR PATENT.
Blued steel hands. Original convex mineral crystal.
Gilt plates and bridges, simple cylinder escapement, serial number 3357 engraved on the dust cover.
Pendulum-type automatic winding device.
Additional device for the mainspring limiter.
Keyless manual setting device.
A specially shaped pendant ring for carrying the watch upright in the pocket.
Overall, it is in good condition.
Although this watch cannot be considered a work of art, the ingenuity and the technical solutions applied make it a very interesting collector's piece, which can be used to study the history of the development of automatic winding devices for mechanical watches.
The winding system is very similar to that of the later "parachuts" automatic movements. What is also striking is that the principles applied to this movement have not undergone drastic changes, and are still used in most of today's automatic winding mechanisms.
History of the automatic watch
After many years perfecting the art of watchmaking, inventors all over the world decided to create new mechanical designs that would allow their watches to wind themselves, letting users wear their watches without fear of breaking their daily routine of supplying energy to their time-measuring machines. The first efforts in this field came in the 1770s, and after that the production of automatic watches spread around the world.
All mechanical watches are driven by the energy of the mainspring, which moves the gears, which in turn move the hands. Because the mainspring loses energy over time, users had to wind it continually by turning the crown or with a key. The automatic watch has mechanisms that use eccentric weights arranged around a pivot, which rotate as the user's wrist moves. This oscillation of the weight created the circular motion of the rotor (which is connected by a series of gears to the final link, the mainspring), and this represents the basic layout of every automatic watch on the market. However, the first examples of this technology had several drawbacks that were overcome over the last 300 years of modern engineering. For example, ways of preventing the mainspring from being overwound.
The history of automatic watches began in the 1770s with the inventions of the Swiss watchmaker Abraham-Louis Perrelet. Perrelet conceived a mechanical device that could, by his calculation, convert the energy created by the movement of the user's body into enough energy to power the automatic watch for 8 days. However, the much more widely publicised automatic watch design came from the French inventor Hubert Sarton (1748-1828), who published his designs in 1778 and managed to show historians that Perrelet's watches were inspired by his work.
Above and below, Abraham-Louis Perrelet
Bidirectional Rotor Automatic
Perrelet's invention is the one that comes closest to the automatic winding system we find in our watches today, through the invention of the bidirectional rotor.
bidirectional. bidirectional.
3 illustrative images of the bidirectional rotor invented by Perrelet
A report to the Geneva Society of Arts in 1776, drawn up by H. B. Saussure, stated that "Master Perrelet, watchmaker, has made a watch in such a way that it winds itself in the wearer's pocket as he walks; fifteen minutes of walking are enough to make the watch run for eight days. Thanks to a modification in the mechanism, continuing to walk does not damage the watch."
Automatic with horizontally suspended oscillating weight
In 1780, the watchmaker Abraham-Louis Breguet bought designs from Perrelet and made several improvements, among them the introduction of the oscillating weight. However, in 1800 he stopped making them, when the public realised that his watches were not reliable.
Two Breguet examples with horizontally suspended oscillating weight
Breguet used this system in several of his celebrated “perpetuélles”, including the iconic Marie Antoinette.
The celebrated Breguet No. 160, better known as the Marie Antoinette
The watchmakers of the time came to the conclusion that automatic pocket watches were a totally useless complication, because if the mechanism was rewound by movements, which had to be ample, such movement was impossible inside a waistcoat pocket.
The real revolution in the automatic watch industry came after the First World War, when advanced manufacturing finally allowed the production of small self-winding wristwatches. As the movement of the hand supplied far more kinetic power than in pocket watches, engineers finally had the opportunity to convert that power more easily into winding mechanisms.
The first automatic wristwatch
This concept was taken up again from the moment watches moved from pockets to wrists, first with a LeRoy of 1922
The LeRoy automatic wristwatch of 1922
John Harwood's automatic
John Harwood
The first watchmaker who managed to do this was John Harwood, a watchmaker from Bolton, England. After claiming the English and Swiss patents for automatic wristwatches in 1923, Harwood began producing watches at his factory in Switzerland in 1928, giving the European public the chance to wear watches able to run for 12 hours once fully wound.
Harwood automatic of 1928 - dial and mechanism
Other brands using Harwood's invention
Other manufacturers immediately embraced John Harwood's designs and began an era of refinement. The famous watch company Rolex added a new system of weights that can move more freely and capture much more energy with each turn (up to 35 hours of reserve when fully wound).
Rolex using Harwood's automatic mechanism
In 1948, Eterna Watch introduced ball bearings into automatic watch designs, allowing much better control over the internal components and the ability to preserve the structural integrity of the watch even when external forces reached critical levels (for example, when the watch was dropped on the floor).
Eterna movement (Calibre 1076H) with the characteristic springs that cushion the impacts of the rotor
Today, most of the world's wristwatches use automatic winding, with only a small percentage of brands still making hand-wound watches. Some automatic watches have embraced the digital age, with weighted rotors that spin inside small electric generators which store their energy in an on-board rechargeable battery (as is the case with Seiko's Kinetic)
Seiko Kinetic movement
History of the Power Reserve
Power reserve indicators were first introduced in marine chronometers. The ability to track latitude and longitude depended on the accuracy of the timepiece, so a power reserve was incredibly useful for reminding the crew when it was time to wind it.
Hamilton marine chronometer (an example from the author's collection)
This type of complication was not widely used in pocket watches, particularly those of the 18th and 19th centuries; one of the exceptions was the Loehr presented above.
The first wristwatch to feature a power reserve indicator was made by Breguet in 1933, but it was a prototype and it would be another two decades before Jaeger-LeCoultre presented the LeCoultre Futurematic. It was the first watch without a crown for winding the mainspring. Instead, it had a sliding mechanism on the back for setting the hands. It was also designed to keep at least six hours of energy at all times.
LeCoultre Futurematic 1955
Launched a few years later, the LeCoultre Powermatic took the Futurematic concept further, concentrating solely on the power reserve indicator complication. An aperture at 12 o'clock revealed a coloured disc, which displayed the energy remaining in the mainspring.
LeCoultre Powermatic
A small problem
The power delivered by the mainspring is not entirely constant. Normally, when a watch is fully wound, the power delivered is greater than in the last hours of the spring, which means that the balance spring will be under different pressures from the mainspring. This can lead to odd measurements when checking the accuracy of the watch at the end of its power reserve.
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