The Gyromax is the trade name for an adjustable mass (or adjustable
inertia
Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes the velocity to change. It is one of the fundamental principles in classical physics, and described by Isaac Newto ...
)
balance wheel
A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position b ...
used in
Patek Philippe
Patek Philippe SA () is a Swiss luxury watchmaker and clock manufacturer, located in the Canton of Geneva and the Vallée de Joux. Established in 1839, it is named after two of its founders, Antoni Patek and Adrien Philippe. Since 1932, the comp ...
wristwatches
A watch is a timepiece carried or worn by a person. It is designed to maintain a consistent movement despite the motions caused by the person's activities. A wristwatch is worn around the wrist, attached by a watch strap or another type of ...
. Instead of weight adjustment screws on the outside of the rim, as in traditional balances, the Gyromax has turnable weights recessed into the top of the rim. The advantages claimed for this design are that, without projecting weight screws, the diameter of the balance can be increased, giving it a larger
moment of inertia
The moment of inertia, otherwise known as the mass moment of inertia, angular/rotational mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is defined relatively to a rotational axis. It is the ratio between ...
, and that it has less air resistance.
The Gyromax balance has six to eight small turnable weights that fit on pins located in recesses around the top of the balance wheel rim. Each of the weights, called ''collets'', has a cutout making it heavier on one side. When the collet's cutout points to the outside of the balance wheel, the heavier side is toward the center which decreases the wheel's moment of inertia, increasing its speed. When the collet's cutout points toward the center, the weight moves outward and the balance wheel turns more slowly. A
watchmaker
A watchmaker is an artisan who makes and repairs watches. Since a majority of watches are now factory-made, most modern watchmakers only repair watches. However, originally they were master craftsmen who built watches, including all their par ...
can turn an individual collet to adjust the wheel's balance, referred to as 'poise', or pairs of opposing collets to adjust the wheel's rotation speed. The Gyromax is a 'free sprung' balance, meaning there is no regulator on the wheel's
balance spring
A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels ...
for adjusting the watch's rate, so the collets are used for adjusting both poise and rate.
Swiss patents were granted to Patek Phillipe for the Gyromax balance on May 15, 1949 and December 31, 1951, and the balance was first used in watches in 1952. Another balance wheel with a similar design is the
Rolex
Rolex () is a Swiss watch brand and manufacturer based in Geneva, Switzerland. Founded in 1905 as ''Wilsdorf and Davis'' by German businessman Hans Wilsdorf and his eventual brother-in-law Alfred Davis in London, the company registered ''Rolex ...
Microstella.
References
{{reflist
External links
THE TIMEZONE WATCH SCHOOL - Watch Glossary - The Balance Wheel - The Adjustable Mass Balance Retrieved Aug. 7, 2007. Short description of Gyromax.
* Odets, Wal
The Balance Wheel of a Watch, The Horologium, TimeZone.com Retrieved Aug. 7, 2007. Technical article on balance wheels by watchmaker, discussing advantages of Gyromax.
Timekeeping components
Horology
Products introduced in 1949