This self-winding chronograph wristwatch crafted entirely in-house was unveiled in 2006; a year after the world’s thinnest split-seconds chronograph was presented.
The Ref. 5960P is a complicated wristwatch with functions that are truly useful in everyday life. It features a totally new self -winding chronograph movement developed and manufactured by Patek Philippe and endowed with a further complication: the patented Annual Calendar mechanism.
The CH 28-520 IRM QA 24H chronograph caliber is a self-winding mechanical movement with a fly back column-wheel chronograph, power-reserve indicator, Annual Calendar, and day/night display. It beats at a frequency of 28,800 semi-oscillations per hour (4 hertz), assuring an extremely constant balance amplitude and high rate accuracy. The winding power is delivered by a unidirectional 21K gold central rotor. Like all Patek Philippe mechanical movements, this new caliber displays the prestigious Geneva Seal.
The chronograph mechanism is based on the venerable column-wheel principle for controlling the start/stop commands. However, it differs from classic Patek Philippe column -wheel chronographs by virtue of a remarkable innovation: The clamps do not control the engagement of a lever-mounted clutch wheel with the chronograph train but instead act on a disk clutch that transmits (chronograph running) or interrupts (chronograph stopped) the power between the fourth wheel and the chronograph hand. This is a highly reliable solution that eliminates the occurrence of backlash-induced hand jitter or bouncing because it does not involve the sudden meshing of teeth when the chronograph is started. It also replaces the conventional three-wheel chronograph train that for reasons of wear made it inadvisable to keep the chronograph running permanently. In this movement, the chronograph hand can be used without hesitation as a continuously running seconds hand; because this has no negative impact on the rate accuracy of the watch, the subsidiary seconds dial customarily found in many chronographs is no longer needed.
The chronograph is operated with two buttons. The one at 2 o’clock starts and stops a measurement. The button at 4 o’clock is used to reset the stopped chrono hand or activate the flyback function when the chrono hand is running.
The patented Patek Philippe Annual Calendar is a full calendar that automatically recognizes months with 30 and 31 days and, assuming that the watch is always running, only needs to be manually corrected once a year on March 1. It displays the day of the week, the date, and the month in three apertures, and it also controls the day/night indicator at 6 o’clock. Its modular design expands the scope of applications of the new chronograph caliber, providing future latitude for extra functions.
The Ref. 5960 stands out with a two-tone dial in charcoal and silvery gray. The distinctive layout is attractive and well organized, giving the watch a delightfully unmistakable personality. All displays are quickly and easily legible. Unlike other chronographs, it does not have three subsidiary dials for the running seconds as well as the minute and hour counters. Instead, it features an unusual combined minute and hour totalizer whose circular dial occupies a large portion of the lower face. On the 60-minute totalizer, the longer red hand counts the minutes on the two outer concentric scales that are graduated from 0 to 30 in red and from 30 to 60 in blue.
The shorter blue hand and the inner scale indicate the duration in hours – up to 12 – of events that last longer than 60 minutes. The ingenious day/night display is based on a small round aperture that progressively changes its color from white (day) to dark blue (night) throughout each 24-hour cycle. It is very useful when the time and calendar displays need to be resynchronized after a longer standstill period. The date changes between 8 pm and 2 am, so manual calendar adjustments must not be made during this period.
The upper half of the dial of the Ref. 5960P is dedicated to the Annual Calendar that displays the day of the week, the date, and the month in three apertures arranged along an arc from 10 to 2 o’clock. The date at 12 o’clock is very prominent. With its polished white -gold frame, the date aperture creates a subtle visual balance with the totalizer that dominates the bottom half of the dial. Depending on the state of wind of the mainspring, the small hand of the power-reserve indicator below the date aperture moves between the plus and minus symbols.
Eight slender applied hour markers in white gold, eleven luminous dots, and the crisp scale graduations deliver the clarity needed for quick time readings. The tips of the leaf-shaped hour and minute hands extend almost fully to the hour and minute indices, and the tip of the chrono hand neatly sweeps the fractional seconds scale.
The very first self-winding wrist chronograph developed and manufactured entirely in-house features a classic round platinum case. It features a small diamond between the lugs at 6 o’clock, the discreet identifier of all of the manufacture’s platinum cases. The antireflection-coated glass and the back are made of sapphire crystal. The two chronograph buttons and the large knurled crown are on the right hand side while the three recessed correction push pieces for the adjustment of the calendar displays are arranged in the left side of the case between 9 and 10 o’clock.
With a case diameter of 40.5 millimeters, the Ref. 5960P is among the larger Patek Philippe timepieces. It makes a solid impression with its technical look and feel, amplified on the wrist by the weight of the platinum case. The chronograph is worn on a brown alligator strap with a platinum fold-over clasp.
Model: Ref. 5960P Annual Calendar Chronograph
Caliber CH 28-520 IRM QA 24H
Self-winding mechanical movement, column wheel-chronograph, Annual Calendar, power-reserve indicator, 24-hour display, sweep seconds (chronograph hand)
Diameter: 33 mm (base movement 30 mm, date ring 33 mm)
Height: 7.68 mm (movement 5.20 mm, calendar module 2.48 mm)
Number of parts: 456 (movement 302, calendar module 154)
Number of jewels: 40 (movement 35, calendar module 5)
Power reserve: Max. 55 hours
Winding rotor: Central rotor in 21K gold, unidirectional winding; oil-free ball
bearing with zirconium balls
Balance: Four-arm Gyromax with four inertia blocks
Frequency: 28,800 semi-oscillations/hour (4 Hz)
Balance spring: Breguet
– Pulled out: Setting the time
– Pushed in: Winding
Center hour and minute hands
Sweep chrono/seconds hand
Power-reserve indicator at 12 o’clock
Subsidiary “monocounter” chronograph dials at 6 o’clock with
– 60-minute counter (it indicates the elapsed minutes on two concentric scales graduated from 0 to 30 in red and from 30 to 60 in blue, respectively)
– 12-hour counter
– Day of week between 10 and 11 o’clock
– Date at 12 o’clock in a polished white-gold frame
– Month between 1 and 2 o’clock
– 24-hour display (day/night) at 6 o’clock
– Chronograph start and stop at 2 o’clock
– Chronograph hand reset and flyback at 4 o’clock
Corrector push pieces:
– Day-of-week correction at 9 o’clock
– Date correction between 9 and 10 o’clock
– Month correction at 10 o’clock
Hallmark: Geneva Seal
950 platinum, sapphire-crystal glass (antireflection-coated) and back, diamond at 6 o’clock
Water resistant to 25 meters
Case dimensions: Diameter: 40.5 mm
Diameter including crown: 43.25 mm
Height: 13.55 mm
Width between lugs: 21 mm
Two-tone charcoal and silvery gray
Eight hour markers in 18K white gold
Eleven Superluminova luminous dots
Leaf-shaped hour and minute hands in 18K white gold with Superluminova luminous coating
Baton-style chronograph hand in sandblasted, rhodiumed steel with counterweight
Power-reserve indicator with baton-style 18K white gold hand, sandblasted and rhodiumed
Silvery gray, azuré subsidiary dial
Baton-style hour-counter hand with counterweight, blue-lacquered brass
Baton-style minute-counter hand with counterweight, red lacquered brass
Hand-stitched brown alligator strap with platinum fold-over clasp