calendario quattro anni cqa – Four-year calendar

The calendario quattro anni is a 4-year calendar displaying the time of day, date, and months. The indices, hour and minute hands, decorated with white gold, are complemented by the orange seconds hand characteristic of ochs und junior, as well as the equally orange date and month displays, which serve as precise accents on the oj blue, circularly brushed dial. The cqa requires correction only in leap years.

The cqa is built around a remarkably clear display concept. The date is displayed in two rows of 15 square apertures each. Each aperture corresponds to one minute interval, allowing its edges to simultaneously serve as minute and second indices. In months with 31 days, the thirty-first day is displayed in the upper part of the aperture of the first day of the month. In the inner circle of the dial, twelve additional apertures indicate the months. The date is adjusted via the middle crown position.

Its mechanical concept follows a principle central to ochs und junior: achieving as much as possible with as little as possible.

Rather than pursuing the complexity of a perpetual calendar, Ludwig Oechslin developed a highly efficient alternative. The cqa uses a system of carefully modified components, including a reworked Maltese cross mechanism, an independently developed switching wheel, and an interplay of partially meshed gears that control the calendar logic with remarkable economy.

A three-toothed wheel governs the transition between months, adding switching impulses depending on the varying month lengths. Months with 30 days require one additional impulse, while February requires three, mechanically advancing past non-existent dates without the additional leap-year logic required by a perpetual calendar.

Because the calendario quattro anni is intentionally conceived as a 4-year calendar rather than a perpetual one, leap-year correction remains a deliberate manual interaction. During leap years, the wearer manually advances the calendar to March 1.