The first self winding watches appeared in the late 1700's. Abraham Louis Perrelet is attributed with inventing the forerunners to modern automatic watches when he developed the first eccentric oscillating weight mechanism in 1770 (below on left) and the first full-rotor winding mechanism (below on right) several years later.




*More recent historians are attrubuting the full-rotor mechanism to Hubert Sarton.

Only a few hundred self winding pocket watches were produced before 1900 making them very rare. Breguet produced a line of automatics called "perpetuelles" starting around 1780, but discontinued them before 1800 because of their unreliable nature. Since they were subject to relatively little motion while in a pocket they could not be utilized to their potential. Wristwatches, on the other hand (pardon the pun), would employ these movements with great success. In 1923, John Harwood patented the first "bumper" wristwatch caliber. The oscillating weight swung nearly 130˚ and had no manual wind capabilities - note the lack of a crown in the pictures below. The hands were set via a rotating bezel. Unfortunately the Great Depression took it's toll and Harwood declared bankruptcy in 1929; his company was liquidated in 1931. Fortis bought the Harwood name and displayed a few pieces several years ago at Basel.

Harwood bumper from 1929



pictures courtesy of WTF member GLADIATOR / Adam



Bumper was slang for a movement with a limited rotation oscillating weight that bumped against a stop as the motion of the wearer's arm caused it to swing back & forth. The weight was also known as a hammer, and it would typically pivot around 120˚ before contacting the stop on either side. Most bumpers only wound the mainspring while turning in one direction and were inefficient devices. Yet even with their deficiencies they were popular into the mid 1950's and many companies including Jaeger LeCoultre, Mido, Omega, and Movado built them in similar forms. JLC built one of the few bumpers with bidirectional winding: the caliber 497, used in their Futurematic series in the 50's. Like the Harwood movement, the 497 had no crown and could not be wound manually. By the early 70's bumpers had finally died out.

Omega caliber 351 in a 1950 Seamaster



Many rapid improvements came between 1930 and 1960, including the 360˚ rotor winding apparatus. Rolex patented their Perpetual system in 1933. Eterna developed a bi-directional automatic winding device in the late 1940's that became the most commonly used in the industry. Most of ETA's movements still employ this system today. Next week we'll cover this in more detail. A slightly different type of automatic winding system is called the microrotor. It's a combination of an eccentric oscillating weight set-up (since it's not pivoted at the center of the movement) and a full 360˚ rotor system. It uses a much smaller diameter rotor than the center mounted automatics, so the rotor must be heavier to generate the same inertia. In 1954 Buren patented their microrotor movement called the Intramatic System. The resulting caliber 1000 and 1001 were released in 1957 powering their Super Slender series. They licensed the technology to companies like IWC, Bulova, and Hamilton. Universal Geneve also debuted a microrotor movement in their Polerouter series about this time, but it was nearly identical in design specification to the Intramatic. Buren won a patent infringement case and U.G. had to pay Buren royalties for each microrotor it used afterwards. Hamilton bought Buren in 1966, and in 1971 SIHH, who owned Omega and Tissot, bought Hamilton. They closed down the Buren factory in 1972. Patek Philippe, Chopard, and Girard Perregaux, among others, have used and/or still install microrotor calibers in their watches today.

Buren Intramatic (left) and Universal Geneve microrotor calibers:

photographs by Jeffrey M. Stein - OnTheDash.com


One more alternative 360˚ winding system uses a peripheral rotor. This facilitates an unobstructed view of the entire movement since the oscillating weight spins around the perimeter. Carl F. Bucherer's new CFBA1000 is the latest version and they have registered it for a patent. Their mechanism is not a clone of an older movement but developed from the ground up, with a dynamic shock absorption system. It uses ceramic bearings and carbon coated rollers to make the rotor system and clutch wheels efficient and virtually maintenance free. The kinetic energy from the rotor is transferred to the winding gears through a transmission wheel that has Incabloc shock jewels on either end of it's axel.

CFBA1000

 

Cool beans!

 

That was interesting, or as Mrs. Blufinz says it..'intristing'. I enjoyed it...thanks Dennis

 

good stuff....and just reminded me that I’m still looking for a bumper...

 

Does anyone have the Buren and Universal patents? I tried to find them on the US and Swiss archives but I didn’t get anywhere.

 

Carl F. Bucherer's new CFBA1000 is a nice piece of machinery. The Harwood bumper from 1929 is like new. I need both.