Gyromax
Encyclopedia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
) balance wheel
Balance wheel
The balance wheel is the timekeeping device used in mechanical watches and some 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 by a spiral spring, the balance spring or hairspring...
used in Patek Philippe wristwatches. 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
Moment of inertia
In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...
, 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
Watchmaker
A watchmaker is an artisan who makes and repairs watches. Since virtually all watches are now factory made, most modern watchmakers solely repair watches. However, originally they were master craftsmen who built watches, including all their parts, by hand...
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
Balance spring
A balance spring, or hairspring, is a part used in mechanical timepieces. The balance spring, attached to the balance wheel, controls the speed at which the wheels of the timepiece turn, and thus the rate of movement of the hands...
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
Rolex SA is a Swiss watchmaking manufacturer of high-quality, luxury wristwatches. Rolex watches are popularly regarded as status symbols and BusinessWeek magazine ranks Rolex No.71 on its 2007 annual list of the 100 most valuable global brands...
Microstella.
External links
- THE TIMEZONE WATCH SCHOOL - Watch Glossary - The Balance Wheel - The Adjustable Mass Balance
- Key Patek Phillipe patents, Patek Phillipe website, Retrieved Aug. 7, 2007. Short description of Gyromax.
- Odets, Walt 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.