Guide to vintage bumper automatic movements

Last Updated on February 27, 2025 by Jason

In the world of vintage watches, the bumper automatic movement holds a special place, representing an era of innovation and ingenuity in mechanical watchmaking. These early self-winding mechanisms, developed in the early 20th century, were an important step towards the modern automatic wristwatch. Despite being eventually replaced by more efficient designs, bumper movements have left an indelible mark on watchmaking history. Today, these movements are beloved by collectors not only for their historical significance but also for their unique operation and charm. In this post, we’ll explore the development, evolution, and legacy of the bumper automatic movement. In addition, we will highlight some notable examples of bumper automatic movements.

The Origins of Automatic Movements

The pursuit of an automatic, or self-winding, watch dates back to the 18th century. One of the earliest innovators in this field was Abraham-Louis Perrelet, a Swiss watchmaker who, in 1777, developed a pocket watch with a weight that moved up and down as the wearer walked. This motion wound the mainspring, theoretically eliminating the need for manual winding. While Perrelet’s design was groundbreaking, it was only partially successful in practice, requiring further refinement.

In the years that followed, other watchmakers attempted to improve upon Perrelet’s idea. The most famous of which was Abraham-Louis Breguet. In 1780, Breguet created a self-winding pocket watch movement he called the “Perpetuelle.” However, despite these early innovations, the automatic winding mechanism did not gain widespread popularity in the 18th and 19th centuries, as pocket watches did not lend themselves well to such designs. The true evolution of automatic movements would have to wait for the advent of the wristwatch in the 20th century.

The Birth of the Bumper Movement

The development of automatic movements for wristwatches began in earnest in the 1920s, when British watchmaker John Harwood successfully revived the concept. Inspired by the simple mechanics of a children’s seesaw, Harwood devised a system where a semi-circular weight, known as a rotor, could move back and forth inside the watch case, winding the mainspring with each movement. Harwood’s innovative design allowed the rotor to move along an arc of about 200 to 270 degrees, with small spring bumpers at either end to absorb the impact as the rotor reached its limits. This “bumping” action gave the movement its name.

Harwood patented his bumper automatic movement in 1924, and by 1928, the first bumper automatic wristwatches were produced, with movements made by A. Schild and cases by Fortis. Harwood’s watches were further distinguished by the absence of a traditional winding crown. Setting the time was done via a rotating bezel, a feature that helped keep the watch completely sealed against the elements.

Unfortunately, despite the brilliance of his design, Harwood’s company was a victim of bad timing. The Wall Street Crash of 1929 and the resulting Great Depression crippled the global economy. This lead to the collapse of Harwood’s business. However, his bumper automatic movement had laid the groundwork for future developments in automatic watchmaking.

The mechanics and legacy of bumper movements

Compared to modern automatic movements, bumper automatics are more delicate and less efficient. The rotor’s travel is limited to about 230 degrees, meaning the movement is less efficient at winding the mainspring compared to full-rotor designs, which allow for 360-degree motion. Moreover, bumper movements only wind the mainspring in one direction, further reducing efficiency. The “bump” itself, caused by the rotor striking the springs at either end of its travel, is a distinctive sensation that collectors of vintage bumper automatics often find endearing.

Despite these limitations, bumper movements were built to high standards, with many examples still capable of accurate timekeeping today. These watches may require careful handling and regular servicing, but their durability and craftsmanship are a testament to the quality of the manufacturers who produced them.

Notable Bumper Movements

Several watch brands produced bumper automatic movements, some of which have become iconic in the world of vintage watches.

Omega Calibre 351

One of the most famous bumper movements is the Omega Calibre 351, which was produced between 1949 and 1952. This movement, also known as the 28.10T1 RA SC PC, featured a sweep second function and was fitted with a 17-jewel configuration. The Calibre 351 had a frequency of 19,800 vph and a power reserve of 42 hours, making it a reliable and well-performing movement for its time. Over 1.3 million units were produced, and the movement was used extensively across Omega’s watch lines, solidifying its place in watch history.

Tissot 28.5-1

Tissot also contributed to the bumper movement era with its 28.5-1 calibre. It was a mechanical movement that was in production from 1944 to 1953. This movement had a sub-second function and was equipped with 17 jewels. Like many other bumper movements of the time, it operated at 19,800 vph and offered a power reserve of 40 hours. Tissot’s bumper movements were valued for their robustness and reliability, and they remain a favourite among collectors today.

Cyma R.420KT

Another noteworthy bumper movement came from Cyma, with the R.420KT calibre. This 17-jewel movement was produced between 1943 and 1954, featuring a sweep second hand and a reliable design. Cyma’s bumper movements were known for their smooth operation and accuracy, making them popular among watch enthusiasts during their production years.

The Rolex influence

Rolex, known for its innovations in watchmaking, did not use bumper automatic movements in its watches. Instead, Rolex patented its Oyster Perpetual movement in 1931. This featured a full-rotor design that allowed the winding weight to rotate a full 360 degrees around the movement. While the rotor only wound the mainspring in one direction, this design was far more efficient than the bumper mechanism. Rolex’s patent effectively locked other watchmakers out of using a 360-degree rotor until the patent expired in 1948.

Despite this limitation, Felsa managed to develop the Bidynator calibre in 1942. This became the first rotor-based automatic movement to wind in both directions. The Bidynator represented a significant advancement in automatic watch technology, bridging the gap between the bumper movements and full-rotor automatics.

Collecting and maintaining bumper watches

For collectors, bumper movement watches offer a unique blend of historical importance and tactile enjoyment. The subtle “bump” felt as the rotor hits its springs is a sensation unlike anything found in modern watches. It adds a layer of charm to these classic timepieces. However, because these movements are now decades old, it’s important to handle them with care and ensure they are properly serviced by a professional watchmaker familiar with bumper movements. A full service is recommended every 5 years for a vintage watch in regular use.

Bumper watches may not be as efficient as their modern counterparts. However, they are still capable of accurate timekeeping when well-maintained. Regular servicing is essential to keep the movement running reliably. Additionally, avoiding exposure to extreme conditions can help extend the life of a bumper movement.

Conclusion

The bumper automatic movement holds a special place in the history of watchmaking. It serves as a stepping stone between the early attempts at self-winding watches and the modern full-rotor automatic movements we use today. Although less efficient than contemporary movements, bumper automatics remain beloved by collectors for their charm, craftsmanship, and historical significance. Whether you’re a seasoned collector or just beginning to explore the world of vintage watches, the unique experience of wearing a bumper movement watch is one that should not be missed. Please let us know if you have any questions in the comments below.