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The Rotor Turns Full Circle

written by J.Goodall - 7th Nov 2011

The winding rotor in watches came into fashion and then largely disappeared because of the Quartz Revolution. Now it has made a strong comeback, writes John Goodall

The most important element in a mechanical watch is the spring, which provides the energy to make it work. The earliest (pocket) watches were wound by means of keys, and then keyless watches marked a big step forward, as it was easier to keep dust from the movement. As early as the 1770, Abraham-Louis Perrelet made the world’s first ever self-winding mechanism for a pocket watch: it used an oscillating weight inside the watch and was designed to wind as the owner walked. Just 15 minutes walk was sufficient to wind it for eight days, according to the Geneva Society of Arts in 1776.

Around 1780, Perrelet sold some of his automatic movements to his contemporary, Abraham-Louis Breguet, who used his watchmaking genius to improve the design. In the first 10 years after he started is own business in 1775, Breguet continued to concentrate on perfecting a number of ideas, and especially the self-winding watch. He went on to develop his own design and produced the first practical automatic watch that could wind itself with a minimum of effort by the wearer and run for up to 60 hours.

Nobody improved on this for a long time and the next major step forward came not from Switzerland but from English watch repairer John Harwood, who lived on the Isle of Man. In 1923 in Switzerland he registered his invention of a self-winding mechanism for a wristwatch. His design was unlike today’s automatics: its winding rotor could not rotate freely through 360°. Instead, the oscillating pendulum completed its travel in one direction and then hit a buffer, commonly known as a bumper now, which sent it off in the opposite direction until it hit a second bumper. Collectors refer to such movements as “bumper automatics”. It used movement of the wearer’s wrist to wind the watch. Instead of using a crown to set the time, Harwood used a rotating bezel that performed the same function – and this also helped to keep dust from the movement by eliminating the winding stem and the tube through which dirt could get inside the case.

Harwood patented his design and it was used by Fortis until 1930. When Harwood went bankrupt in that year, his patent expired and Hans Wilsdorf, who had founded Rolex in London, seized the opportunity to take up the concept, but Rolex modified it so that the rotor could rotate through a full 360°. The first automatic Rolex watches appeared in the 1930s, under the name Oyster Perpetual. The company patented its first self-winding mechanism with a perpetual rotor in 1931 – and a similar concept is at the heart of most automatic watches made since then.

In 1948, Eterna introduced another significant step forward when it used five steel ball bearings for the rotor, instead of the conventional bearing. The movement was called the Eterna.Matic and since that time five dots, symbolising the ball bearings, have formed Eterna’s logo. Since then ball bearings have been widely used, but more recently a number of companies have used ceramic ball bearings because they are harder wearing and require no lubrication.

A variety of winding techniques have been employed, including unidirectional and bi-directional rotors. A unidirectional rotor turns in both directions, but only winds as it turns in one direction, while a bi-directional rotor winds as it turns in either direction.
It is important for good functioning of a mechanical watch that the mainspring is wound up during the time when the watch is subjected to the most movement – daytime for most people. It provides more consistent timekeeping when well wound than when it is partly run down. That is why self-winding watches, which wind the mainspring when the watch is moving around, offer an advantage over their hand-wound counterparts. (It is also why it is best to wind a watch in the morning and not at night.)

By 1957 the first generation of electrically powered watches appeared, but they were relatively short-lived. Until the 1960s virtually all wristwatches contained mechanical movements, but then in 1960 Bulova launched the Accutron, a watch with a battery-driven movement regulated by a tuning fork that vibrated at 360Hz. This produced a faint hum, as might be expected of a tuning fork, with a pitch of F sharp. The tuning fork was powered by a one-transistor electronic oscillator circuit, so the Accutron qualifies as the first electronic watch. More than four million had been sold when production stopped in 1977. (A limited edition reproduction of the original was produced again by Bulova last year. The brand is now owned by Citizen.)

The first quartz wristwatch ever sold was made by Seiko and sold on Christmas day 1969, followed months later by quartz watches from a number of Swiss companies that had all invested in the same research consortium.

Quartz watches proved to be so much more accurate than their mechanical counterparts – and in a short space of time, so much cheaper – that they soon dominated the market. The Japanese were able to increase production to match rocketing demand, while the Swiss lagged behind in production, mainly because of shortages of some key components. Switzerland’s mechanical watch industry began to die and thousands of staff were made redundant. Many never returned to the industry.

In the latter part of the 1980s, there was a gradual revival of interest in mechanical watches, led by the Swiss and today, in the quality sector of the watch market, mechanical watches rule again. Not only are almost all high grade watches mechanical, but more than ever before are automatic. The winding rotor has made a great come-back.

Now, watch rotors are not just functional elements of a watch; they have become important features of some watch designs, too. Appropriately, one brand that uses the rotor as a design feature is Perrelet, whose brand name has been inspired by the founder of automatic winding. Others have used rotors as design features above the dials of watches, including Perrelet. In 2009, Carl F Bucherer succeeded in producing a movement with a peripheral rotor – in the form on an arc, instead of the conventional shape that obscures so much of the movement. It circles around the outside edge of the movement and is not visibly attached to the centre of the moment. The owner is able to admire the full beauty of the movement, without a rotor above it to obscure his view.

Few admire a quartz watch for its beauty and certainly not for the craftsmanship that has gone into its production nor for the loving choice of materials or the craftsmanship needed to decorate the quartz movement. After almost falling by the wayside in the 1970s and 80s, mechanical watches have come back with a bang and to watch lovers, they are here to stay – and especially automatics with their all-important rotors.

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