Patek Philippe caliber 28-28 Q SQU

28-28 Q SQU description

The Patek Philippe calibre 28-28 Q SQU is a self-winding perpetual calendar movement developed for the Cubitus and distinguished by its square format and ultra-thin construction. Crafted in the manufacture’s Grand Complications workshops, it measures 28 x 28 mm with a thickness of 5.04 mm and consists of 313 parts. Its layout combines the perpetual calendar and moon-phase mechanisms with an off-centre mini-rotor integrated into the movement, allowing the calibre to remain notably thin for its complication level.

The perpetual calendar is governed by a 48-month cam and automatically accounts for months of 31, 30, and 28 days, as well as 29 February in leap years. According to Patek Philippe, it will not require correction until 2100. The displays comprise subsidiary indications for day, date, month, leap-year cycle, and 24-hour indication, together with a moon-phase aperture. Calendar corrections are made via four recessed correctors in the case flank. The moon-phase display is rated to a deviation of one day in 122 years.

The movement uses a rhodium-plated off-centre 22K gold mini-rotor with unidirectional winding and delivers a power reserve ranging from a minimum of 38 hours to a maximum of 48 hours. It runs at 21,600 semi-oscillations per hour and is equipped with a Gyromax balance and Spiromax balance spring. The calibre bears the Patek Philippe Seal. In the 5840P-001, the movement is skeletonized and visible through the sapphire case back, with openworked bridges, a rhodium-plated balance, transparent jewels, and blued screws.